sailboat bridge clearance

Bridge Clearance

Do you ever need to know the tide heights if you're not crossing a shallow bar? Maybe.

It could be that problems arise above the water. A low bridge can block passage for fly-bridge cruisers and sailboats on high tide, yet let them pass with space to spare on low. Sometimes even runabouts can be blocked by low-hanging roadways.

You obviously need to know your boat 's bridge clearance if you navigate anywhere that passage beneath one of these structures is common. The bridge clearance (BC) refers to the height from the waterline (where the surface meets the hull) to the highest point of any structure on the boat, including the mast, tuna tower, or outriggers. (If your radio antennas and riggers fold down, you don't have to measure them in the equation.)

Boat Bytes_

It's always best to punch around in the backwaters on a rising tide, and to head back for deeper water shortly before the tide peaks and starts to run back out. That way, if you go aground inside, the rising water gives you a good chance to get off anc escape; while if you ground on falling water, you're stuck until the next incoming tide.

Boater-ese.

Bridge clearance (BC) is

the distance from a boat's waterline to the highest point on the topsides. It indicates the height of a bridge under which a boat can pass.

Bridge clearance is listed on marine charts, with the height above mean high water given. So, if you want to pass under a bridge that has 20-foot listed clearance with your sport-fisherman boasting a BC of 19'6'', you aren't going to be able to get through at the peak of a spring tide that's a foot taller than normal high tide (more on spring tides later in this chapter). On the other hand, you can get through that bridge with a 19-foot listed clearance on the bottom of a -1.0 low.

Bet You Didn't Know

In most areas there's a normal progression through four tides, but some days have only three tides. How can this be?

As the 50-minute-per-day regression takes place, the P.M. tide gradually advances past midnight, thus leaving one 24-hour period without four tides, even though the tidal movements maintain their steady procession.

Continue reading here: If Your Boat Springs a Leak

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Readers' Questions

How to determine if a bridge should be tall or movable to allow ships to pass under it?

There are several factors that need to be considered when determining if a bridge should be tall or movable to allow ships to pass under it. Height of the ships: The height of the ships that will be passing under the bridge is one of the most important factors to consider. The bridge needs to be tall enough to accommodate the highest ships that will be using the waterway. Frequency of ship traffic: If the waterway sees a high volume of ship traffic, it may be more practical to build a movable bridge that can easily be raised and lowered to allow ships to pass through. This can help to reduce congestion and delays for both road and water traffic. Cost and feasibility: Building a tall bridge may be more costly and require more engineering and construction expertise than building a movable bridge. The cost and feasibility of each option need to be carefully considered before a decision is made. Environmental impact: Building a tall bridge may have a bigger impact on the surrounding environment compared to a movable bridge. Environmental factors such as wildlife habitats, water quality, and scenic views need to be taken into account. Regulatory requirements: There may be specific regulations and requirements that dictate the design and construction of bridges over waterways. These regulations may specify the maximum height of the bridge, the types of ships that need to be accommodated, and other considerations that need to be taken into account. Ultimately, the decision to build a tall or movable bridge will depend on a combination of these factors and will require careful planning and consideration to ensure that the bridge meets the needs of both road and water traffic.

What is the maximum bridge clearance of a 2002 sea ray 360?

The 2002 Sea Ray 360 has a maximum bridge clearance of approximately 18 feet 10 inches or 5.7 meters.

What clearance does a bridge need for boat sto sfaley pass?

The clearance required for a bridge to safely pass boats will vary depending on the size and type of boats that typically travel in the area. Typically, for small pleasure boats and small commercial vessels, a clearance of at least 15-20 feet is usually sufficient. However, for larger vessels such as sailboats and yachts, a clearance of at least 50 feet or more may be needed. It is important to consider the height of the masts and antennas of the boats that will be passing under the bridge when determining the necessary clearance.

How tall is the bridge between cross lake and rush lake for boats?

I'm sorry, but I couldn't find any specific information about a bridge between Cross Lake and Rush Lake in my database. Could you please provide additional details such as the location or any other names associated with the bridge?

What is the clearance under the boston university bridge?

The clearance under the Boston University Bridge is approximately 21 feet.

How tall is a bertram with a flybridge in feet?

The height of a Bertram with a flybridge can vary depending on the specific model and design features. However, on average, a Bertram with a flybridge may have a height ranging from around 14 to 18 feet.

How to read bridge information sailboat?

To read bridge information on a sailboat, you can follow these steps: Understand the types of bridges: Familiarize yourself with different types of bridges that you may encounter while sailing, such as fixed bridges, swing bridges, lift bridges, bascule bridges, and pontoon bridges. Consult nautical charts: Use nautical charts specific to the area you are sailing in. Nautical charts will provide detailed information about bridge locations, clearance heights, opening schedules, and other relevant details. Identify bridge symbols: On nautical charts, bridges are typically marked with specific symbols. Learn to recognize and interpret these symbols to identify the type of bridge and its characteristics. Note vertical clearance: Pay attention to the vertical distance between the waterline and the bridge structure. This information will help you determine if your sailboat can safely pass under the bridge without any height restrictions. Check the opening schedule: For movable bridges, consult the nautical charts or contact local authorities to determine the bridge's operation schedule. It is essential to be aware of any specific opening times and restrictions to plan your sail accordingly. Use official publications: Utilize official sailing publications like the United States Coast Pilot or similar guides for bridge information. These publications provide additional details such as radio frequencies to contact bridge operators and any special considerations. Listen to VHF radio communications: While sailing near bridges, monitor the VHF radio channels that bridge operators use. They may provide updates on the bridge status, closures or any specific instructions for sailing through. Keep a lookout: Maintain a sharp lookout for any visual signs or signals displayed by the bridge operators, such as lights, flags, or signs. These signals may indicate whether the bridge is open or closed to vessel traffic. Plan your route: Consider the bridge clearances, opening schedules, and other navigational factors when planning your sailing route. Ensure to account for any potential delays caused by bridge operations and adjust your schedule accordingly. Follow navigation rules: When approaching and passing through bridges, ensure you adhere to navigation rules and any instructions provided by bridge operators. Maintain a safe distance and follow any direction to pass safely. Remember, bridge information can change, so it is crucial to stay updated with the latest charts, local notices, and radio communications to ensure a safe and hassle-free sailboat journey.

How tall a ship can fit under the newportpell bridge?

The height clearance under the Newport Pell Bridge, located in Newport, Rhode Island, is approximately 207 feet (63 meters). This gives ships with a height of up to 207 feet the ability to pass under the bridge safely.

What does horizontal bridge clearance mean on a boat?

Horizontal bridge clearance on a boat refers to the measurement of the distance between the waterline and the highest point on the boat that could potentially collide with a bridge or other overhead obstruction when passing underneath it. It is an important consideration for boat operators to prevent damage to the boat and ensure safe navigation in areas with low bridge clearances.

What is the hight of a 50 azimut yacht?

The height of a 50-foot Azimut yacht can vary depending on the specific model and design. However, a general estimate for the height of a 50-foot Azimut yacht would be around 20-25 feet. It is always best to consult the manufacturer's specifications or contact the specific model's seller for precise measurements.

What is the max height of a boat to go under 8.5’ canal bridge coral gables?

The maximum height of a boat to go under an 8.5' canal bridge in Coral Gables is usually around 7.5 - 8 feet. This allows for some clearance between the boat and the bridge to ensure safe passage. It is important to always check the specific bridge clearance height as it can vary depending on factors such as tides and construction.

What is reasonable bridge span length to allow passage of sail boats?

The length of a reasonable bridge span for sailboats can vary depending on several factors, such as the type and size of sailboat, the height of its mast, and the location of the bridge. In general, a bridge span length of around 65 feet (20 meters) is considered reasonable to allow passage for most sailboats. However, larger sailboats with taller masts may require bridges with higher clearances or even drawbridges that can be opened to accommodate their passage. It is important for bridge designers and operators to consider the local boating traffic and ensure sufficient clearance for safe passage of sailboats.

What is the highest clearance under jubilee bridge in highest tides?

The Jubilee Bridge, located in Cornwall, England, has a fixed clearance of approximately 5 meters (16 feet) at mean high water springs. Therefore, the highest clearance under the bridge during the highest tides would also be around 5 meters.

What is max bridge clearance for ships?

The maximum bridge clearance for ships varies depending on various factors including the design of the ship, its size, and the waterway it is navigating. The bridge clearance refers to the vertical distance between the waterline and any overhead structure that the ship needs to pass under, such as a bridge or powerline. In general, larger ships have a lower maximum bridge clearance due to their size and draft. For example, large container ships or oil tankers may have a bridge clearance of around 55 meters (180 feet) or less. On the other hand, smaller vessels like yachts or pleasure boats typically have a higher bridge clearance, usually ranging from 10 to 20 meters (33 to 66 feet). It is important for ship operators and captains to be aware of the maximum bridge clearance to ensure safe passage and avoid any collisions or damage to the ship or overhead structures. Navigation charts, local regulations, and communication with control towers or bridge operators are crucial in determining and maintaining a safe clearance for ships.

How tall are bridges on the interstate?

The height of bridges on the interstate can vary depending on the location and construction standards. Typically, the minimum clearance height for interstate bridges is around 16 feet or 4.9 meters. However, there can be exceptions where certain bridges may have lower clearance heights due to various factors such as road design, geography, or infrastructure age. It is important to note that these measurements may vary and it is always advisable to follow posted clearance signs and height restrictions to ensure safe passage.

What size boat can get under whitten neck bridge nh?

I'm sorry, but as an AI language model, I don't have access to specific data such as the height of the Whitten Neck Bridge in New Hampshire. However, typically, the clearance height of bridges is indicated by signs or local regulations. I would recommend contacting local authorities or boating associations in the area for accurate information about the clearance height of the Whitten Neck Bridge and the size of the boat that can safely pass underneath it.

What foot clearance for a bridge does a new 26 twinvee need?

The foot clearance for a bridge required by a new 26 Twin Vee boat may vary depending on local regulations, construction standards, and the specific design characteristics of the boat. It is recommended to consult the manufacturer's documentation or contact the Twin Vee company directly for accurate information regarding the required foot clearance for bridges.

What is the height above the waterline of a norman 23 motor cruiser?

The Norman 23 Motor Cruiser has a height of approximately 6 feet above the waterline.

How to calculate bridge clerance from vessel?

The bridge clearance is the height of the lowest overhead part of the ship's superstructure above the waterline of the vessel. To calculate bridge clearance, you will need to measure the distance from the waterline of your vessel to the lowest point of your superstructure. Subtract the waterline measurement from the superstructure measurement to get your bridge clearance.

What is the minimum and maximum clearance on the underside of a bridge?

? The minimum clearance on the underside of a bridge is typically determined by the load capacity of the bridge and the height of the bridge deck above the water. The maximum clearance is usually determined by the height of the waterway below the bridge.

What is bridge clearance of a 2006 sea ray 260 when on a boat trailer videos?

The bridge clearance for a 2006 Sea Ray 260 when on a boat trailer is 8' 6".

What is the bridge clearance for a 1981 55ft, sea ranger pilothouse trawler?

The bridge clearance for a 1981 55ft Sea Ranger Pilothouse Trawler can vary depending on which model you have, but in most cases it will be anywhere from 19ft to 21ft.

How high a bridge should be above the river for boats to pass through?

The answer to this question depends on the size of the boats that will be passing through the river. Generally, bridges need to have a clearance of at least a few meters (typically 6-12 m) above the highest expected water level in order to ensure that the boats can pass underneath safely.

Can a sail boat go under the lyndon johnson bridge?

No, sailboats typically cannot travel under the Lyndon B. Johnson Bridge due to its height restrictions. The bridge spans 177 feet above the water, which is too high for sailboats to travel safely underneath.

What size boat can go under the bridge into surfers?

paradise The size of boat that can go under the bridge into surfers paradise would depend on the height of the bridge and the size of the boat. Generally, boats that have a beam (width) of less than 7'10" and a mast (height) of less than 22' can pass beneath the bridge.

Do boats fit uner the ponte cestio?

Yes, boats can fit under the Ponte Cestio, which is a bridge located in Rome, Italy. The bridge has a clearance of around 8.5 meters, which should be high enough to allow most boats to pass underneath.

How to find a boats bridge clearance?

To find a boat's bridge clearance, first take a look at the bridge itself. Get the exact measurements of the bridge and make sure you know the height of the water when you plan to be traveling under it. This will help you determine what your clearance will be. If you are uncertain, contact the bridge operators and inquire. They should be able to provide the height of the bridge, as well as the depth of the water when you plan to pass underneath it. This will help you calculate your exact bridge clearance.

What bridge clearance does a 30 foot sea ray cruiser need?

The recommended bridge clearance for a 30 foot Sea Ray Cruiser is at least 11 feet.

What is the bridge clearance for a nordhavn 64?

The bridge clearance for the Nordhavn 64 is approximately 15 feet.

What is the clearence of the rt 54 bridge in high tide fenwick island?

The RT 54 Bridge in Fenwick Island does not have any specific clearance due to high tide. The U.S. Coast Guard maintains a navigation channel under the bridge that is 15 ft. deep at mean low water and has a vertical clearance of 35 ft. at mean high water.

What is the maximum bridge height clearance for a sea ray sundancer 260?

The maximum bridge height clearance for a Sea Ray Sundancer 260 is 13 feet 0 inches (3.96 meters).

Can a pontoon boat fit under a bridge that is 7'4?

" tall No, most pontoon boats have a bridge clearance of 8 to 10 feet.

What does trans am height mean on a boat?

Transom Amidships Height (TAH) is the distance from the waterline to the top of the transom. This measurement will often be used when choosing the right outboard or inboard motor for a boat.

How tall is average bridge height?

The average bridge height varies significantly depending on the type and purpose of the bridge. Generally speaking, the average height of a highway bridge is around 15 meters (50 feet), while a railway bridge averages around 21 meters (70 feet).

What is the boat clearance on the sundance bridge, southport?

The bridge clearance for most boats is 25 feet.

How hight is the sundale bridge for a fly ridge boat?

The Sundale Bridge has an Air Draft of 24 feet 6 inches.

How do you figure out bridge clearance of a boat?

The best way to calculate the bridge clearance of a boat is to measure the height of your boat's mast or highest point from the waterline to the top of the object. This should be done while the boat is in the water and not while it is out of the water, as the measurements may vary. Then, subtract that measurement from the bridge's clearance height, as posted on a bridge marker near the bridge itself. The difference between mast height and the posted clearance height is your boat's bridge clearance.

What is height for clearance of flybridge boat sundale bridge southport?

The clearance for the Sundale Bridge in Southport is 6m (19.68 feet).

How to read bridge high for boat?

To determine the clearance height under a bridge for a boat, you can follow these steps: Obtain the bridge clearance information: Research the specific bridge you want to pass under and find its official clearance height. This information is usually available in boating charts, guidebooks, or online resources. It is important to note that bridge clearance heights can vary depending on factors such as tides and water levels, so you might need to consider these variables as well. Determine your boat's height: Measure the height of your boat from the waterline to the highest point on your vessel. This might include antennas, masts, or other protruding elements that increase the overall height. Make sure to measure accurately and account for any potential changes due to additional weight on board. Adjust for tides and water levels: Considering the current conditions of the water level, calculate if it will affect the boat's vertical clearance. If the tide or water level is significantly higher than usual, it might decrease the bridge clearance. Take the time to research tide tables or contact local marinas for information on water level fluctuations if needed. Compare boat height with bridge clearance: Subtract the height of your boat from the bridge clearance height, taking into account any adjustments for tides or water levels. The resulting figure will indicate the amount of clearance space available. Ensure that there is sufficient clearance for your boat to safely pass through without any obstructions. It is crucial to exercise caution when passing under bridges to prevent collisions or damage to your boat. Always double-check the provided clearance information and plan your routes accordingly. Additionally, check for any potential clearance restrictions due to overhead power lines or other obstructions near the bridge.

How should you pass a fishing boat?

When passing a fishing boat, you should slow down and ensure that you pass at a safe distance. You should also use appropriate signal lights and sound signals to indicate your intentions. Additionally, give the boat's occupants plenty of time to respond before continuing to maneuver your vessel.

How high is a 10ft beam , can it get under a bridge?

No, a 10 ft beam cannot get under a bridge. The typical clearance height for a bridge is between 12 and 15 ft.

How to do field bridge measurements in a sail boat?

Field bridge measurements in a sail boat are typically done to measure and determine the performance of the sailboat in various conditions, such as wind speed, direction and strength. The measurements are generally done using a bridge-like instrument known as a field bridge, which is attached to the boat and measures the forces acting on the vessel in the water. These forces can then be used to calculate the speed, direction, angle of heel and other performance parameters. The measurements can be done while the sailboat is at rest or sailing, depending on the type of field bridge measurement being done.

How high is a 28 ft searay above the waterline?

Typically, a 28 foot SeaRay boat will measure about 8 - 10 feet above the waterline when fully loaded.

Are bridge clearances given for high water?

Yes, bridge clearances are given for high water levels. High water levels can affect the clearance underneath a bridge and must be taken into consideration when calculating bridge clearances.

How to calculate bridge clearance for boat?

To calculate the bridge clearance for a boat, you need to take the height of the bridge, subtract the height of the boat, and then subtract the height of the mast.

How high is a typical sail boat above water?

The height of a typical sail boat above water typically ranges from 3-ft to 15-ft, depending on the boat's design and sail configuration.

Is bridge clearance based on high tides or low tides?

Bridge clearance is usually based on the highest expected tidal range in the area.

How high does a bridge have to be for a boat to pass beneth it?

The height of a bridge for a boat to pass beneath it depends on the size and height of the boat. Generally, a bridge should allow at least 15 feet of clearance for boats traveling underneath it.

How do they measue clearance under a bridge?

Clearance under a bridge is typically measured using basic surveying equipment such as a total station or laser rangefinder. A surveyor will measure from the bridge deck to the ground, or from the bridge deck to any other obstacle that the bridge must clear.

How to increase the clearance in bridge?

Increasing the clearance in a bridge involves various considerations and engineering solutions. Here are some possible steps to increase the clearance: Evaluate the bridge: Determine the current clearance and the required increase in clearance. Assess the bridge's structure, age, and load capacity to ensure that it can accommodate any modifications. Modify the roadway: If possible, lower the road surface by excavation or reducing the pavement thickness within the bridge approach areas. This can create more space for the clearance above. Adjust bridge parapets: Parapets are the protective walls on the sides of the bridge. Modifying or replacing them with lower-profile ones can increase the vertical clearance. Modify the bridge deck: Consider increasing the thickness or replacing the bridge deck with a thinner material, which can help raise the vertical clearance. Redesign or replace the bridge girders: Girders provide the structural support for the bridge deck. If replacement is feasible, consider using girders with a shallower profile to increase the clearance. Modify the bridge abutments: Abutments are the supports at the ends of the bridge. Adjusting or replacing them with shorter ones may allow for a higher clearance. Use specially designed arches or trusses: In some cases, adding arches or trusses under the existing bridge can increase the clearance without significantly altering the structure above. Divert or relocate the roadway: If feasible, consider modifying the roadway alignment to bypass the bridge completely or relocate it to a nearby location with better clearance. Seek professional guidance: Consult with bridge engineers and professionals to assess the bridge's specific conditions, evaluate potential solutions, and ensure compliance with applicable regulations and safety standards. Always keep in mind that altering a bridge's clearance requires professional expertise and adherence to safety regulations and standards.

What does 2.2m height clearance mean?

2.2m height clearance means that the area has a minimum clearance height of 2.2 meters. This could refer to the clearance of a doorway, ceiling, or any other space.

What is the average height of a bridge from the water?

The average height of a bridge from the water is approximately 20 meters (65 feet).

What do you need to know when passing under a river bridge boaters test?

When preparing to pass under a river bridge during a boater's test, there are several important things you need to know, including: Bridge clearance: You must know the clearance height of the bridge to ensure your boat can safely pass under it without hitting any part of the structure. This information is usually posted on a sign or marker near the bridge or in nautical charts. Boat height: Measure the height of your boat from the waterline to the highest point, such as an antenna or mast. Compare this measurement to the bridge clearance to determine if your boat can safely pass through. Antennas and equipment: Take into consideration any antennas, equipment, or other protruding features on your boat that could increase its overall height. Include these items when measuring the boat's height and determining if it can clear the bridge. Tides and water levels: River levels can fluctuate due to tides, rainfall, or other factors. Consider the current water level before attempting to pass under a bridge, as lower water levels may increase the clearance while higher water levels can decrease it. Navigation aids: Look for any buoys or markers that indicate safe passage or channel boundaries around the bridge. These aids can guide you through the correct path and maintain proper clearance. Traffic and speed: If there is significant boat traffic or strong currents near the bridge, adjust your speed and course accordingly. Be aware of other vessels and follow any right-of-way rules to safely navigate the area. Safety precautions: Always maintain a proper lookout and keep a safe distance from other boats. Turn on your navigation lights, use a horn or whistle to signal your approach, and communicate with nearby vessels if necessary. Remember, it is important to follow all rules and regulations set forth by local waterway authorities and the boating licensing agency in your area. Additionally, be mindful of any specific instructions provided during your boater's test regarding passing under bridges.

Can a 10 foot high boat get under the bridge at route 603 bridge boat clearence?

No, 10 feet is too high to fit under the Route 603 bridge boat clearance.

How to determine if your boat will fit under a bridge?

To determine if your boat will fit under a bridge, you need to consider the height of the bridge and the height of your boat. Here are the steps to follow: Measure the height of your boat: Measure the highest point of your boat, usually the highest part of the mast, antenna, or other structures. This measurement will give you the overall height of your boat. Research the bridge height: Find out the height clearance of the bridge you want to pass under. Bridge heights are usually marked on navigational charts or indicated by signs posted on the bridge itself. Compare the measurements: Compare the height of your boat to the clearance height of the bridge. Ensure that the height of your boat is lower than the clearance height of the bridge. It is essential to have some margin to account for factors like tides, waves, or potential errors in measurements. Account for any potential changes: Consider the impact of tides, waves, or other factors that could affect the height of your boat. For example, if the tide is high, it might increase the overall height of your boat and make it impossible to pass under the bridge safely. Seek local knowledge or expert advice: If you are unsure about the height clearance or have concerns about passing under a particular bridge, consult local marinas, boat clubs, or other experienced boaters who are familiar with the area. They can provide you with valuable information and tips about specific bridges. Remember, it is crucial to ensure sufficient clearance before attempting to pass beneath a bridge. Underestimating the height or attempting to squeeze through with little clearance can be extremely dangerous and lead to severe damage to your boat or injuries.

What is boat bridge clear with arch?

Boat bridge clear with arch is a type of bridge designed specifically for small boats. It has an arch-shaped clearance which allows boats to easily pass underneath without having to negotiate any steep incline. This type of bridge is especially useful in areas where there are large bodies of water, but the span of the bridge is too small for a full-size bridge.

How to know bridge height and which boat works?

Bridge height can be determined by contacting the local bridge authority or by measuring the distance from the water's surface to the bridge. The type of boat that works best will depend on the size of the boat, the type of water it is traversing, and the type of bridge.

How to find clearance under bridge in tides problem?

To find the clearance under a bridge in a tidal situation, you need to take into account both the water level at high and low tides. The clearance will be the difference between the highest high water mark and the lowest low water mark. In other words, the clearance under a bridge in a tidal situation is the difference between the highest flood tide level and the lowest ebb tide level.

Can boats go under the 212 bridge in milledgeville?

No, boats cannot go under the 212 bridge in Milledgeville. The bridge is too low to allow boats to pass through.

How to determine if a ship can fit under a bridge?

To determine if a ship can fit under a bridge, the clearance height of the bridge should be measured and compared to the height of the ship. Additionally, factors such as the width of the ship, the width of the bridge, and the curvature of each structure should be considered.

What is the bridge clearance for a super yacht?

The bridge clearance for a Super Yacht depends on its height, as well as the features and capabilities of the specific Super Yacht. Generally, a Super Yacht will require a minimum clearance of around 20 – 25 feet in order to pass under most bridges.

How to find out boat's height?

To determine the height of a boat, you will need to consult the specific boat manufacturer or boat model’s specifications. Each boat manufacturer or boat model will have different measurements for height. You can consult the boat manufacturer’s website, contact the manufacturer directly, or measure the boat yourself with a measuring tape from the highest point of the boat to the water line.

What boat can you buy with heigh clearance of 10 feet?

You can buy a pontoon boat with a height clearance of 10 feet.

What is term for the height of a boat?

The height of a boat is usually referred to as the draft.

How do i find the clearance under bridges?

Depending on the bridge, you can usually contact the Department of Transportation in your area to inquire about the clearance under bridges. Additionally, some states may provide online resources, such as maps or charts, that you can use to find the clearance under bridges in that state.

How to determine bridge clearance on a yacht?

Bridge clearance on a yacht can be determined by measuring the height of the top of the yacht’s mast from the waterline. This measurement will be compared to the height of the bridge from the waterline. The difference between the two measurements is the bridge clearance.

How to come up with bridge clearance for transport of boat?

In order to come up with a bridge clearance for transport of a boat, you will need to research the bridge height where you are planning to transport the boat. Additionally, you will need to consider the size and draft of the boat and any other structures or protrusions (such as a sail or mast) that may need to be taken into account when determining the bridge clearance.

How to come up with bridge clearance on boat bid calculation?

Bridge clearance is calculated by taking the overall length, width and height of the boat and subtracting it from the height clearance of the bridge. The height clearance of the bridge should be known prior to calculating the bridge clearance of the boat.

What is hor clearence boating?

Hor clearance boating is the process of sailing a boat beneath a bridge or other low overpass. It involves careful maneuvering and precise timing to ensure that the boat does not collide with the obstruction.

What kinda boat will fit under bridge clearence of 5 feet?

A boat with a draft (depth below waterline) of less than 5 feet should fit under a bridge clearence of 5 feet.

What is the maximum height of your boat if you pass brayden water at high tide?

The maximum height of your boat will depend on the type and size of your boat, as well as the local tide conditions.

How is a boays bridge clearance figured?

Boyes Bridge clearance is typically figured by calculating the difference between the bridge height and the height of the tallest object (ship, vehicle, etc.) that will be passing through the bridge. This calculation can generally be completed by adding the height of the object to the water level, and then subtracting the bridge height.

How height of the bridge to let the boat pass under?

The height of the bridge will depend upon the size of the boat. It should be high enough to allow the boat to pass under it.

How to measure bridge height of a boat?

To measure the bridge height of a boat, you will need to use a tape measure or a ruler. Start by measuring the distance from the waterline to the top of the bridge. This measurement is the bridge height. Alternatively, you can use a laser rangefinder for a more accurate measurement.

What is the bridge clearance on cobia boats?

Cobia Boats do not release specific information about the bridge clearance on their boats. It would be best to contact their customer service directly for this information.

What does gridge clearance mean on a boat?

Gridge clearance is a term used to describe the vertical distance between the highest point on the deck of a boat and the underside of the bridge or overhanging structure above. This is important in determining if a boat is able to safely pass through a bridge or other overhead obstacles.

How to calculate bridge clearance?

Bridge clearances are determined by the vertical distance between the bridge deck and either the water level or the bridge approaches. In most cases, bridge clearance is calculated by subtracting the bridge deck elevation at the highest point of the arch from the elevation of the lowest point of the arch. In other cases, bridge clearance is determined by taking the difference between the bridge deck elevation at the lowest point of the arch and the water level. In either case, the result gives an estimate of the vertical clearance available for vessels beneath the bridge.

What does bridge clearnce at mean high water mean?

Bridge clearance at mean high water is the vertical distance between the mean high water mark and the underside of the bridge. It is the minimum vertical clearance that a vessel must have in order to safely pass under a bridge at mean high water.

What is the bridge clearance for buccaneer 210 sailboat?

The bridge clearance for the Buccaneer 210 sailboat is approximately 30 feet.

What is a bridge clearance aboard a ship?

Bridge clearance aboard a ship is the vertical distance between the ship's deck and the lowest overhead object, such as a bridge or other structure that the ship may pass under.

What is the minium bridge clearence for an intrepid boat?

The minimum bridge clearance for an Intrepid Boat is 8 feet.

How to calculate boat bridge clearence on trailer?

To calculate the boat bridge clearance on a trailer, you will need to consider the following factors: Boat Height: Measure the height of your boat from the highest point, such as the top of the windshield or any antennas or structures on top of the boat. Trailer Height: Measure the height of your trailer from the ground to the highest point, usually the top of the trailer frame or the fenders. Hitch Height: Measure the height of the hitch point where the trailer connects to your vehicle. This measurement is important to ensure that the trailer is level when attached to the towing vehicle. Ground Clearance: Measure the distance between the ground and the lowest point on the boat or trailer. This is essential to ensure that the trailer does not bottom out on steep inclines or uneven surfaces. Once you have these measurements, you can calculate the boat bridge clearance by subtracting the total height of the boat and trailer (boat height + trailer height + hitch height) from the specified bridge clearance height. The bridge clearance height refers to the minimum distance between the bridge and the road surface. It is crucial to have enough clearance to avoid any damage to your boat or trailer when passing under a bridge. If the calculated clearance is less than the bridge clearance height, it is advisable to find an alternative route or choose a different trailer to transport your boat if possible.

How to.measure the height of outriggers to water line plus bridge?

To measure the height of outriggers to the water line plus bridge, you will need to follow these steps: Gather the necessary tools: You will need a measuring tape or a laser distance measurer, a level, and a pen or marker to record the measurements. Determine the starting point: Find a stable and level surface near the outriggers and water line where you can begin measuring. This could be the dock, a nearby platform, or any solid ground. Measure the distance from the starting point to the water line: Use a measuring tape or a laser distance measurer to measure the vertical distance from the starting point to the water line. Ensure that the measuring tape or laser is level and perpendicular to the water line for accurate measurement. Record the measurement: Once you've obtained the distance from the starting point to the water line, write it down or make a note of it. Measure the distance from the water line to the bridge: Move your measuring tape or laser distance measurer to the location where the bridge is situated. Again, ensure that the measurement is level and perpendicular to the bridge. Determine the height of the outriggers: Subtract the distance from the water line to the bridge (step 5 measurement) from the distance from the starting point to the water line (step 3 measurement). This will give you the height of the outriggers from the water line to the bridge. Note down the measurement: Write down or make a note of the calculated height of the outriggers. By following these steps, you should be able to accurately measure the height of the outriggers to the water line plus the bridge.

What is Pine Island bridge save clearance for boats?

The Pine Island Bridge has a vertical clearance of 25 feet at mean high water.

Is a boats bridge clearance in the water or on the trailer?

It depends on the type of boat and trailer. Boats typically have clearance in the water, since they are designed to float freely on the surface. Some boats are designed to partially submerge when being towed, while others may require a tall trailer to ensure enough clearance over the road.

How to measure Max Bridge Clearance on a boat?

The best way to measure the maximum bridge clearance on a boat is to use a measuring tape or a laser distance measurer. Start at the top of the highest point of the boat's superstructure, and measure straight up to the boat's highest point. This will give you the maximum bridge clearance of your boat.

What does maximum bridge clearance mean for boats?

Maximum bridge clearance is the maximum height of an object (usually a boat) that is allowed to pass through or under a bridge or other type of overhead structure. This is generally determined by the height of the bridge and the draft of the boat, which is the vertical distance between the waterline and the lowest part of the boat's hull. If a boat's height is greater than the bridge clearance, it must take an alternate route.

Where is a boats bridge clearance measured from?

A boat's bridge clearance is typically measured from the waterline to the highest point on the vessel.

What is bridge clearance on a boat?

Bridge clearance on a boat is the vertical distance from the waterline to the highest point of the boat, usually the top of the mast or arch. This is important to know as it can determine which waterways a boat can safely navigate.

Bridges have to be factored in when planning a trip. Depending on where you cruise, you may be dependent on bridge openings; a particular bridge's schedule can often decide where you tie up for the evening or when you wake up and get underway the next day. While many are high (over 65 feet) and some usually remain open (such as railroad bridges), others are restricted for different hours in specific months, closed during rush hours and/or open on the quarter-hour, half-hour or even at 20 minutes and 40 minutes past the hour.

To add to the confusion, the restrictions are constantly changing. Just because a bridge opened on a certain schedule last season does not mean it is still on that same schedule. Changes are posted in the U.S. Coast Guard's Local Notice to Mariners . It is also a good idea to check locally to verify bridge schedules before your transit.

Measuring Vertical Clearance

Most bridges carry a tide board to register vertical clearance at "low steel" or the lowest point on the bridge. (Note that in the State of Florida waters the tide board figure–and the one noted on the chart–is generally for a point that is 5 feet toward the channel from the bridge fender.) In the case of arched bridges, center channel clearance is frequently higher than the tide gauge registers. So check your chart and the tide boards and, unless it specifically notes that vertical clearance is given "at center," you may be able to count on a little extra height at mid-channel, under the arch of the bridge. Some bridges may bear signs noting extra height at center in feet.

Calling a Bridge

Most bridges monitor VHF Channel 13, designated by the Federal Communications Commission as the "bridgetender channel" until you get to South Carolina (southbound), where it changes to VHF Channel 09. (The exception is the locks on the Okeechobee Waterway, which respond to VHF Channel 13). 

In any waters, it is a good idea to monitor both the bridge channel and VHF Channel 16–one on your ship's radio and one on a handheld radio, if your main set doesn't have a dual-watch capability–to monitor oncoming commercial traffic and communications with the bridgetender.

When using VHF, always call bridges by name and identify your vessel by name and type (such as sailing vessel or trawler) and whether you are traveling north or south. If you are unable to raise the bridge using VHF radio, use a horn signal.

Note that some bridges are not required to open in high winds. If you encounter a bridge that won't open (for whatever reason), it is prudent to drop the hook in a safe spot until the situation is resolved.

Bridge Procedures

First, decide if it is necessary to have the drawbridge opened. You will need to know your boat's clearance height above the waterline before you start. Drawbridges have "clearance gauges" that show the closed vertical clearance with changing water levels, but a bascule bridge typically has 3 to 5 feet more clearance than what is indicated on the gauge at the center of its arch at mean low tide. Bridge clearances are also shown on NOAA charts.

Contact the bridgetender well in advance (even if you can't see the bridge around the bend) by VHF radio or phone. Alternatively, the proper horn signal for a bridge opening is one prolonged blast (four to six seconds) and one short blast (approximately one second). Bridge operators sound this signal when ready to open the bridge, and then usually the danger signal–five short blasts–when they are closing the bridge.

The operator of each vessel is required by law to signal the bridgetender for an opening, even if another vessel has already signaled. Tugs with tows and U.S. government vessels may go through bridges at any time, usually signaling with five short blasts. A restricted bridge may open in an emergency with the same signal. Keep in mind bridgetenders will not know your intentions unless you tell them.

If two or more vessels are in sight of one another, the bridgetender may elect to delay opening the bridge until all boats can go through together.

Approach at slow speed and be prepared to wait, as the bridge cannot open until the traffic gates are closed. Many ICW bridges, for example, are older and the aged machinery functions slowly.

Once the bridge is open, proceed at no-wake speed. Keep a safe distance between you and other craft, as currents and turbulence around bridge supports can be tricky.

There is technically no legal right-of-way (except on the Mississippi and some other inland rivers), but boats running with the current should always be given the right-of-way out of courtesy. As always, if you are not sure, let the other boat go first.

When making the same opening as a commercial craft, it is a good idea to contact the vessel's captain (usually on VHF Channel 13), ascertain his intentions and state yours to avoid any misunderstanding in tight quarters.

After passing through the bridge, maintain a no-wake speed until you are well clear and then resume normal speed.

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The Right Way To Navigate Bridges

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At some point in your travels here and there by boat, you may have to request a bridge opening. Here's how to do it right.

A crowd of boats wait for a timed bridge to open. (Photo: Mel Neale)

Whether you have to deal with bridges only occasionally or every day, you'll probably have to deal with them at least sometimes. If your boat has very little air draft, you may think there's not much to worry about. But there may be, and the issue of whether you're too tall to get under is only one of many. Here's what to expect when your way is blocked by spans of steel and cement with eighteen-wheelers flying overhead.

Barriers To Safe Passage

Obviously, you must avoid bridge pilings and the structure surrounding bridges. But you must also deal with eddies around them, which may affect your steering. Sailboats have particular issues because the wind may change, causing temporary calms or shifts. It is usually imprudent, and often illegal, to use sails to go through a bridge — unless that's your only means of propulsion. The pilings may obstruct vision, which is important regarding oncoming traffic, but also for avoiding small boats that often hang out around the pilings to fish.

Communities often build trailer ramps on one side of bridges. This means that small boats and skiffs may be blithely taking off from behind the pilings, heading into the path of boats coming through the bridge. Whether you're steering around pilings or through a span, all boats must be extra vigilant, using necessary signals and prudent maneuvering. Rules of the Road are very important, not to mention common sense.

Who's On First?

Usually boats must funnel through a particular span of a bridge, which may require opening. Special right-of-way considerations may come into play. For example, if a boat is heading with the current, other boats heading into the current should normally let the boat being pushed come through first. Smaller nimble boats should generally stay out of the way of a large boat with more limited maneuverability. An outboard skiff darting around the bow of a ponderously moving tug and barge may be obscured from view of the pilothouse. This is true anytime, but particularly in areas of restricted maneuverability around a bridge. And what boater can possibly think his engine can never fail at just the wrong time?

Requested Vs. Scheduled

Many bridges must open to let taller boats through. Sometimes these bridges open on request if given proper signal, but many bridges only open at scheduled times. Always signal the bridge for an opening. Signals include horn blasts (usually a long and a short), but most boats call the bridge tender on the VHF. Bridges stand by on channel 9 or 13, depending on location. Call the bridge by its name (e.g., North Landing Bridge, Barefoot Landing Bridge, Seventeenth Street Causeway Bridge). Otherwise the wrong bridge may think you need an opening. Names of bridges and proper VHF channels are best found in updated guidebooks, where you will also find local rules and customs. Be aware that some bridge names may change. For many years, tugs going through the Atlantic Intracoastal Waterway (AICW) swing bridge south of Little River Inlet, South Carolina, called it, melodically, the "Little River Swing" (pronounced "swang.") Now the bridge is named the "Captain Archie Neil 'Poo' McLauchlin Swing Bridge" after a well-known local legend. The captain may be sitting in his favorite establishment watching as you go by.

This sailboat was dismasted by a bridge. Fortunately, no one was injured. (Photo: Mel Neale)

It's often difficult to plan ahead for scheduled bridge openings because typically the current will change in the channel ahead. This is particularly true in areas where inlets or creeks run to larger bodies of water, such as the ocean. A creek may produce current, speeding you along, but as you pass its intersection, the current turns against you. People who simply plug distance to run into a chartplotter are often fooled.

Communication Is Key

Even if the boat ahead of you has requested an opening, you also should request one so that the bridge tender knows how many boats are coming through. We've known bridges to close on boats that haven't properly notified the operator. Often, when the bridge is in the open position, the bridge tender has limited visibility. Going through in a single file line is usually best because boats on the other side may also be coming through and space is limited.

Sometimes a bridge tender will instruct pleasure boats to wait for a tug and barge or other vessels because of that vessel's special needs or space limitation. Pay attention. Keep a VHF tuned to the bridge's operating channel well before you approach the bridge, as well as during the transit, because there may be special issues such as a malfunctioning bridge, a fire/rescue vehicle approaching on the highway, or other problems. If you know in advance, you can slow down and come through when the situation has cleared.

Into The Melee

When you reach a bridge, there may well be a crowd of boating traffic. If the bridge opens only on a schedule or is otherwise restricted (such as bridge work or emergency highway traffic), it is critically important to take into consideration the special maneuvering needs of other boats (including your own) when you're waiting in a crowd. Try to stay clear. For example, often a sailboat will have little control when backing or require a wide turning radius. Large vessels may have very little maneuverability in tight quarters. Often a tug with a barge must simply keep coming, unable to dodge around smaller boats.

Some vessels may have huge windage issues that make steering and positioning very difficult, especially if the wind is blowing across the channel or toward the bridge. Others, such as deep draft vessels, may be susceptible to strong currents pushing them toward the bridge and may need to face away from the bridge into the current or wind until the opening. Then it will have to turn, and there might not be room to do so within its turning radius. And just as boats have different handling characteristics, skippers have different skill levels. We've passed through many bridges over the years, and my favorite tactic is to remain at the end of the line to hopefully avoid trouble. Don't hang too far back, though, because the bridge tender has an obligation to get the highway traffic moving when he can.

To make matters worse, some bridges are situated poorly from a boat operator's perspective. The Wappoo Creek Bridge just south of Charleston, for example, spans a narrow channel that doglegs. The current is immense, and a large boat coming through on a fair tide may have trouble making the turn. And this bridge usually operates on a schedule. Check the charts to get the "lay of the land" long before you approach a bridge.

Watch Out For Power Lines

High-voltage power lines can carry hundreds of thousands of volts across rivers and bays. Power lines that cross navigable waterways are marked on charts with their clearance listed as from the height of mean high water (MHW), which is an average of several years of high tides. If the power lines are near a bridge, their lowest clearances are required to be higher than the bridge. However never take a chance with "close." Floods or surges can diminish the clearance. Also, voltage has been reported to jump from a power line to the mast top even though that mast top may not have actually touched the line. In addition, extremely hot days may cause some sagging, as could wind, lightning, or other damage to the supporting towers.

According to the U.S. Coast Guard, should your boat come in contact with a power line, don't jump into the water. The electrical charge may pass through your boat and electrify the surrounding water. The safest approach is to stay in the boat and avoid touching anything metal. Leave the boat only after it has moved away from the line.

— By Charles Fort

How High Is Too Low

Even if you think your boat's air draft can pass under a bridge, you still may need an opening. The theoretical vertical clearance of fixed bridges on the AICW is 65 feet (except for the 56-foot Julia Tuttle Bridge in Miami). But this is "sometimes." An unusually high tide, flooding from excessive rain, or storm tide can make it less. We've seen sailboats dismasted because they underestimated the clearance. Some sailboats will hang loaded dinghies or heavy jugs of water out to the side on a spinnaker pole and a halyard to cause a heel that will allow them through. (Not a good idea!) Most wisely go out to sea for that part of the passage or wait for sufficiently low water. Other waterways besides the AICW have different height restrictions. For example, 55 feet for the Florida Gulf Intracoastal Waterway and 49 feet for the Okeechobee Waterway.

Extra high tides may mean trouble for tall-masted ­vessels. (Photo: Mel Neale)

There are usually tide boards at each bridge that show the vertical clearance at the center of the span (or wherever it's the highest), but sometimes these are damaged. It's difficult to "eyeball" vertical clearance. Standing on your deck and looking up creates an optical illusion making the overhead span seem much closer. Sometimes bridge tenders will help, but often they aren't allowed to because of the liability. If you can't clear the span and you're too close to the steel girders, the current or wind may prevent you from stopping in time.

Trawlers and other "short" boats may have a similar problem with a lower bridge, which they would normally need to open. If that bridge is timed, they may want to get under anyway and this requires absolute knowledge of your boat's air draft and the bridge's vertical clearance. The maximum vertical clearance of many bridges is typically at or near the center of the center span, not off to the side, although there are some significant exceptions to this. Bridge tenders sometimes tell captains to lower antennas and outriggers, etc. Requiring an opening just because you don't want to lower your antenna or outrigger isn't lawful.

It Takes Us All To Tango

When a bridge tender does try to be helpful or give you advice, remember that you're the skipper of your boat and are normally ultimately responsible. Many tenders have little actual experience running boats. Some also will become impatient with ignorant or impolite boaters. However, these incidents are not the rule and are often exaggerated. Bridge tenders must juggle many interests, all with the demands of the situation, which can include winds, tides, storms, currents, and poorly trained skippers. If you do have a problem, the U.S. Coast Guard has a "Bridge Office" in each district that you can contact. Typically bridge tenders are anxious to help, many going out of their way to do so. Some are boaters themselves. It takes all of us to make it work.

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Learn About Bridge Clearance

Here’s a peek at our BRIDGE episode of our Ask Captain Chris training DVDs! Let us know if you’d like to learn more. Posted by Captain Chris Yacht Services on  Thursday, December 19, 2013

Beware of your next bridge clearance. Many of you have spent the summer cruising the fresh waters of North America. Lulled into sliding under fixed bridges like the 20 footers on the Erie Canal, you now need to WAKE UP and be prepared for tidal, salt water cruising…

First, check your charts for bridge air clearances. This is based on average high tide. Next, check the tide level to determine if you need to request a drawbridge to be opened. Remember, you should only ask to have a bridge opened if you have lowered everything including your VHF radio antennae. Maybe you arrived at the bridge during low or mid tide and you will actually have more headroom!

A great example of this is in Georgia where 8 foot tides are not uncommon. Really EIGHT FEET! If the chart shows a bridge having 20 feet of air draft then that refers to the clearance at mean high tide. Sometimes the air draft could be less with a higher than average tide or strong winds keeping the water in the ICW. But at low tide you might have as much as 28 feet to slide under the bridge.

Always look for the ruler fixed to the bridge fender system. That will show airdraft for the edge of the bridge span. This measuring board is often accompanied by a smaller white square sign which may show additional clearance at center if the bridge has an arc in the design. If in doubt, call the bridge tender on your VHF- sometimes channel, 9 sometimes channel 13.

Learn more about drawbridges by watching our BRIDGES Video available from our Ships Store . Sixty minutes of surprises you may expect when clearing a fixed or drawbridge and how to transit a bridge like a pro. Get ready for the fall cruising season with Captain Chris. The Holidays are fast approaching and this video would make a great stocking stuffer for the captain or crew in your life.

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NO LOITERING at the Bridge

NO LOITERING. Ever heard No Loitering regarding boating habits? We teach that important phrase when learning about close quarters maneuvering aboard your boat. NO LOITERING. When waiting to enter a lock or a drawbridge NO […]

Phone: 772.205.1859 | [email protected] | Copyright © 2006 - 2023 Captain Chris Yacht Services LLC. All rights reserved.

Do you know your numbers when it comes to sizing up your boat? Accurate measurements for figures like length, draft, beam and clearance will keep your boat free from damage in marinas and private boat dock slips as well as while traveling beneath fixed bridges.

Boat length is measured from the bow to the stern. However, the number is not as set in stone as it may seem. It can vary depending on whether there’s a swim platform, a bow pulpit, a dinghy on a davit or other things that contribute to the length overall (LOA). Knowing the correct length of your boat is just as important as knowing how to properly operate it. We’re not talking about that number the manufacturer says it is … the one that’s part of the model name. For example, a Hatteras GT45X is 45 feet long, but with a swim platform and a bow pulpit, it could technically come closer to a total of 47.5 feet. This number can change from boat to boat (even among the same model and manufacturer) as well as type of boat. Correct length is especially useful when docking or choosing a private boat dock rental. Trying to fit a boat into a slip that’s too small can result in damage to the boat, the dock and other property around it.      

Example Average Length

• Cruising Sailboat: 16’ – 50’
• Catamaran: 32’ – 47’
• Cabin Cruiser: 25’ – 45’
• Motor Yacht: 29’- 65’
• Center Console: 18’ – 32’

Another important factor is draft. A boat’s draft refers to the vertical distance from the waterline (where the hull touches the water) to the bottom of the hull, or keel on a sailboat. It determines the minimum depth of water a boat can safely navigate without running ashore (which, by the way, is very bad). Put simply, it helps you know how deep the water needs to be. Like length, it can vary from boat to boat. A sailboat can have a very large draft based on whether it has a keel (and whether the keel is removable). Each dock has its own specific draft allowance, which is based on things like water level, tides and how flat or angled the ground is under the water. One dock can be vastly different than others in the area. Dock draft measurements can be taken by dropping a long length of rope (weighted) or chain into the water, marking it at the water level and then measuring from the bottom up out of the water. Private docks on our site are listed at the low tide water level. This way, you know the absolute minimum depth of water. It’s always best to be conservative by one or two feet if you’re not completely sure you’ll be able to dock at that boat slip – due to things like changing tides, weather and boat wakes. 

Boat Size vs Draft

• Low Draft: A boat 32 feet long and under needs 3 feet or less of water
• Medium Draft: A boat 45 to 65 feet long needs 4 to 5 feet of water
• High Draft: A boat 65 feet long or greater needs 5 to 7.5 feet of water

To throw a wrench into these statistics, there are instances where this might vary. Sailboats can be an exception as they may have a non-retractable keel, which gives them the need for a larger draft (since the keep gives them a bigger draft measurement). On the other hand, since catamarans are wide and displace water very efficiently, they may only need 4.5 feet of draft even if it falls into a bigger category.

Average Boat Draft

• Cruising Sailboat: 5’ (but could be more if it has a non-retractable keel)
• Catamaran: 2’ – 4’(large cats could need more)
• Cabin Cruiser: 3’
• Motor Yacht: 4’ (the bigger the yacht, the bigger the draft)
• Center Console: 2’

As a general rule, the bigger the boat is, the deeper the draft will need to be. Factors like weight and beam play into this concept. The hull shape can also play a part. A flat or multi-hull boat (like pontoon boats, jet skis and dinghies) has a low draft. A deep V-shaped displacement hull (like most power boats and cruisers) allows the boat to sit deeper in the water, resulting in a high draft.

Beam refers to the distance from the widest point of the boat to the other side (think: middle of the boat from side to side). Catamarans are very wide compared to that of center consoles and cabin cruisers. Most boats fall into the 18 to 20-foot beam category, but cats can be as wide as 22 to 30 feet.

The beam of a boat will determine how wide of a boat slip rental you need. You’ll want to measure the dock to make sure it’s wide enough that your boat won’t bang against the sides.

Average Beam

• Cruising Sailboat: 12’
• Catamaran: 22’ to 30’
• Cabin Cruiser: 8.5’
• Motor Yacht: 13’
• Center Console: 9’

Clearance, or vertical clearance, is important for sailboats and catamarans with a fixed mast, as well as sportfish boats with tall towers. It refers to the height of the boat from the waterline to the top of the mast or flybridge (or any non-removable part). Some masts can be lowered, so that would not be included in your clearance number.

Out in the wide-open ocean, clearance isn’t too much of an issue. The time it becomes an issue is when you’re sailing under a fixed bridge. A drawbridge is no problem. You just need the patience to wait till it opens. Sailboats can require anywhere from 35 to 75 feet of vertical clearance, so you’ll want to check out those fixed bridge heights when charting your course or choosing a boat dock for rent. Be sure to take into account low tide when determining clearance.

Average Boat Clearance

• Cruising Sailboat: 50’
• Catamaran: 39’
• Express Cabin Cruiser:  9’ 10 “ with tower up / 7’ 7” with tower down
• Motor Yacht: 14’ to 15’
• Center Console: 9’ 6”

Whether you’re docking your boat at a marina, a mooring or a private boat dock rental, the correct measurements play a big factor. Hopefully this has given you some good advice to make the whole docking process a bit easier. Now if you could just control the wind while docking.  

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Bridge Procedures

Nautical charts only tell you that there is a bridge and what the horizontal clearance (width) and vertical clearance (height) are. The vertical clearance is the one you are probably going to be most concerned with, i.e. will you fit under the bridge or will you have to open it?

You should consult your chart for the note on heights; most will show minimum vertical clearance at mean high water. That means if you are at the bridge at any time other than high tide, you should have more clearance than shown. (You’ll be able to tell exactly when you get there.) You should, prior to planning a trip, consult the Coast Pilot or Cruising Guides for the area you will be traveling and make notes in your trip log concerning bridges including the name of the bridge, hours of operation, recommended method of contact, etc.

According to U.S. Coast Guard regulations, you may be subject to both criminal and civil penalties for causing an unnecessary bridge opening because of “any nonstructural vessel appurtenance which is not essential to navigation or which is easily lowered.” In other words, if the only thing making you open the bridge is your VHF antenna or outriggers, take them down. These same regulations also provide penalties for any bridge tender who “unnecessarily delays the opening of a drawbridge after the required signal has been given.”

Even if you can navigate under the bridge with plenty of clearance, always slow down and do so at idle speed. You can not see if another boater is on the other side, out of view, until the boat suddenly darts out into the bridge channel.

Other things to look for as you approach the bridge is a blue sign with what looks like a telephone receiver with a lightning bolt through it. This will give you the radio frequencies that the bridge monitors (usually 16 and 13 or 9). It is customary, at least in most areas, to contact the bridge tender by VHF radio to request an opening, however, there is a sound signal that can be used. To sound signal the bridge use one prolonged blast followed within 3 seconds with one short blast. The bridge tender will acknowledge an OK with the same signal. If there is a problem in opening at that time the bridge tender will answer with a “NO” by sounding five short blasts. You acknowledge your understanding of the “NO” by responding with five short blasts.

On the bridge you will also find a white sign that shows the hours of operation and special operational procedures. You should note that some bridges open on demand year-round and some only open on demand during certain parts of the year. In areas like South Florida, where the population grows significantly in the winter time, many bridges open only at certain times (like every half-hour) during the season.

You may also find regulatory signs on bridges with information on speed limits or other warnings. In many cases speed limits may change at a bridge so be careful to heed these regulatory signs. The bridge structure makes a great place to set up a marine speed trap.

When approaching a bridge at night you will see three red lights in a triangular pattern. The two lower lights indicate the bridge opening just above water level and the center light hangs from the center of the bridge span. If you line up with the center light and keep the relative relationship of the lower lights equidistant on either side you can be assured that you are in the center.

While waiting for the bridge to open be aware of your position and make sure that current is not carrying you into the bridge. I remember sitting behind a sailboat a few years ago waiting for the bridge to open. I guess the skipper of the sailboat took the opportunity to go below for some reason. No amount of shouting, blasts on the horn or calls on the radio were successful in raising him as his boat was carried by the current and his mast made contact with the bridge. Luckily, not much damage was done and he was able to back away.

Once the bridge is open proceed through with caution. Many times, if there is wind or current, you may find your steering affected. Keep a close eye out and try to anticipate any corrections that need to be made. Be sure to look out for other boats that may be waiting on the other side who also want to come through during the opening. Once clear of the bridge you may resume the permitted speed for the area and it is a good idea to thank the bridge tender.

About Chris

Outdoors, I’m in my element, especially in the water. I know the importance of being geared up for anything. I do the deep digital dive, researching gear, boats and knowhow and love keeping my readership at the helm of their passions.

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Laura La Cagnina on December 24, 2019

Once a day they raise the bridge even when no boat needs to go through. My question is do you have to wait until the bridge is down to go through? Thanks L

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Calculate Clearance Under Bridges & Cables

• Post author: Noel Hutchinson
• Post published: October 25, 2019
• Post category: Uncategorized
• Post comments: 0 Comments

This article will show you how to calculate clearance under bridges & cables. We often need to do this in order to see if our vessel can fit underneath. Or we may have to work our when our vessel can fit underneath as it may need the tide to fall to a certain level.

When working out this puzzle, the first thing we need to do is find the charted height of the bridge or overhead obstruction. We can either find this on the chart itself or by looking up the information in an almanac or pilot book.

Overhead clearances under bridges & cables are measured above something called HAT or Highest Astronomical Tide. This is the highest a tide can rise due to influence of celestial bodies and weather. For a reminder of the different tide levels take a look at the image below or click through to the video.

So the next step is to find the height of HAT from the tide tables. Once we have done this we know the height of the bridge and the level above which it is measured.

The thing with HAT though is that it’s not that common. HAT is the highest a tide can be expected to rise. However, the tide often falls short of that level. This means that we often have some extra space. This space comes from the difference between the height of tide (HoT) on the day and HAT.

In order to find this extra bit of space we need to use a tidal curve or an App to get the height of tide. We can then take the height of tide off of HAT. This is our extra bit of space.

HAT – HoT = extra space

You can refresh yourself on tidal curves here if you need to:

How To Use Tidal Curves – watch the video

The Final Calculation

To calculate clearance under bridges & cables then, all you need to do is add the charted height and the extra bit of space together. This will then give you the total space available for a given time on a given day.

In order to see if you will fit under the bridge take the air draft of your vessel from the total space available. If the answer is positive then you can make your way underneath safely. The air draft is the height of the vessel from the waterline to the very top.

Here’s a summary of the steps to take:

• Get the charted height from the chart or almanac
• Get the level of HAT from the tide tables
• Calculate the height of tide (HoT) using the tidal curve (or use an App)
• Take the HoT from HAT to work out the extra space
• Add the extra space to the charted height for total clearance
• Take the air draft of the vessel from the total clearance to see if the vessel can fit

Calculate Clearance Under Bridges & Cables Cheat Sheet

As always, we have produced a free cheat sheet for you to use. It will make the steps super simple and help to keep you organised as well. We find the best thing to do is laminate it. Then you can use it again and again with a dry wipe marker pen or china-graph pencil ?

Please don’t forget to like, comment and share.

Our complete set of Knowledge Cards are available from our shop

Noel Hutchinson

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What “good” bridgedeck clearance is and why is it important? – Richard Woods Interview # 4

• Post author By Diane Selkirk
• Post date February 4, 2021
• 2 Comments on What “good” bridgedeck clearance is and why is it important? – Richard Woods Interview # 4

Editor’s Note: These videos are meant to be introductions to basic catamaran design considerations. For more in depth discussions please contact Richard Woods via his website or comment below on this article. We welcome questions and suggestions.

In this interview, we talk to Richard Woods about one of the most important characteristics of cruising catamaran design – bridgedeck clearance. It is a feature that is often too low especially on small catamarans. Richard explains that while bridgedeck clearance seems like a simple yet elusive measurements, it is in fact a very complicated design characteristic that catamaran architects have to thoroughly think out.

Can I get an inflatable dinghy underneath? A question Richard Woods suggests asking to determine if a catamaran has enough bridge deck clearance.

For more information or to purchase build plans from Richard Woods, please go to his website at www.SailingCatamarans.com .

Please see Episode 1 for an introduction of Richard, Episode 2 to learn about galley locations, and Episode 3 for a primer on why cruising catamaran bows are an important purchase design decision .

Tell us a little bit about what bridge deck clearance is?

The bridge deck is essentially the part of the catamaran that you stand on. It is the space between the hulls. It’s not just the saloon but also the cockpit and the forward anchor lockers. It’s one of the most important design features that you have because the waves can come up and hit underneath. Structurally a bridge deck slamming into waves is not as bad as it sounds, but it sounds really really scary when you have too low a bridge their clearance.

That’s why it’s always important to check on the clearance that you’ve got if you’re buying a catamaran.

I’ve been on boats where you haven’t been able to put food on the saloon table while we’ve been sailing because it just gets thrown off. It’s just so horrible especially when you’re sailing to windward or in a confused sea.

What kind of distance are we talking about – feet inches meters?

What I tend to tell people to do is to make sure that they can get a conventional inflatable dinghy underneath their boat. A high bridge clearance would be three feet. But just looking at the boat and saying, “Can I get an inflatable dinghy underneath?” which is essentially about 18 inches.

Obviously the bigger the boat the easier it is to have a good clearance because people don’t get any bigger when the boat gets bigger, so you don’t need more than standing headroom in the saloon.

On a small boat that’s going to be really challenging and so anything under 30 feet it’s essentially impossible to have standing headroom and good bridge deck clearance.

I guess you’d end up with a really tall boat.

So you talked about slamming when you don’t have enough bridge deck clearance, but is that the main thing that occurs do you run into any problems with steering the boat is slamming just a physical discomfort.

You want the bridge deck to be as short as possible, and that’s because there’s three factors.

One can be from the waves just sailing along in flat water. Two hulls make waves, and they cross underneath the bridge deck. You can get a lot of interference just in flat water with the waves hitting underneath. If you have a low bridge deck clearance and the hulls close together, you can have the water hitting the bottom with no waves. The further apart you have the hulls, it becomes sort of a a mole hill of interference rather than the mountain that you’re sailing over. So that’s one factor that contributes to the slamming whatever sort of boat you have.

Then the second factor is that as you start sailing into waves the boat’s going to pitch up and down and so the bars go down and up. That’s why you want the bridge deck clearance as far back and as high as possible. The bridge to clear should start as far back as possible, so it doesn’t bash into the waves.

Then there is a third factor with that. If you can easily imagine that if you had the bridge that starting a long way back, but it had a vertical front. Every time a big wave came, it would slam into that front, so you want to have a gentle curve in front which is essentially usually under the anchor lockers. It’s got the benefit that the anchor lockers drain easily because the water will run to the back.

So you want (1) a high bridgedeck, (2) that clearance you want it to start as far back as possible, and (3) you want a gentle slope.

When we’re talking the gentle slope you mean the underside of the boat?

When the bows pinch up, the stern goes down. The same applies to the stern and the cockpit. You really want to have the cockpit higher than the middle of the boat. The boat pitches around the middle right, so the lowest point can be in the middle, and you want it as high as possible.

The stern is lower, but obviously at the stern you’re not going to have waves slamming into the back unless it’s really bad.

So those are the priorities. A high bridge deck underneath, a sloping front that starts as far back as possible, and a higher cockpit then is a good thing.

Then you’ve got the bows as well because the hulls are making waves, and so a lot of people including myself make a quite an exaggerated s-shaped knuckle. The waves that hit come up and break away instead of going up and hitting the bridge deck .

On the inboard side you often see boats with either quite a chambered inner hull side or the knuckle arm to help deflect the spread and waves down.

Then there’s a another factor which is that most bridge decks are flat underneath across the boat, but it’s actually much better to have it slightly fade.

(Editor’s note: Richard models with his hand during this portion the effects of the wave. Please refer to video).

One of the times when it’s very obvious is if you have an outboard in a cell with a flat base. An outboard in the cell is very close to the water. Even if the bridge deck is high, you can hear that slamming badly.

When somebody’s looking for bridge deck clearance if the boat is in the water, what kind of clues are you looking for?

The anti-fouling line is going to be a big factor, but on a lot of boats like for example the Fountaine Pajots being one in particular the anti-fouling line is deliberately taken quite a bit above the real water line.

There’s good reasons for that. One is that it saves all the dirty scum along the water because the anti-fouling paint goes higher.

The other is that your eye is taken to the top of the antibody line so effectively reduces the freeboard. That’s why people do it.

So that makes it a bit misleading as to where the real clearance is. So another good one is that basically no one designs a catamaran with transoms immersed. If you look from the transom and look forward, you should probably get an idea of how much clearance there is, and you should always take a tape measure with you. Then you can just very quickly see what it is. A tape measure is always handy when you’re looking at things.

I know that one of the things that will bring down your bridge deck clearance is having too much gear on board. So when you’re looking at a new boat that’s emptied out of gear, are there any rules of thumb to know how far down that’s going to sink as you as you load it up?

That’s another thing. You’ve always seen pictures of boats. They’re saying we just launched it and it’s floating on its marks. It’s brilliant. Well no that’s awful because they haven’t got half a ton of water and fuel on board. They haven’t got a ton of people on board.

The boats always get heavier and heavier and heavier and over the lifetime they’ll go down hugely. Inches.

The other problem with that of course is when the boat’s heavier it doesn’t respond to the waves so quickly. So you get more bridge deck slamming the heavier you are which is another factor that people say. You want to keep the boat light, so it goes fast.

But in fact you want to keep the boat light, so that it’s more lively and bounces over the waves rather than plows through them. So it’s just more comfortable all around.

That was a big thing that I found from going ocean sailing that when I decided that I was going to go and not come back. I took everything with me, and then every time I flew home back to England, I would take stuff off the boat and fly home with it because I realized that I didn’t want all that stuff.

Definitely. It’s easy to think you need all the all the comforts of a home aboard where you really need to divest stuff.

Thank you for bridge deck information. It sounds like there’s more to look for than just sort of how many inches above the water. There’s all the design shape and everything. That’s really great information. Thank you Richard!

• Tags Buying Advice , Richard Woods

By Diane Selkirk

I love to travel and have spent the past seven years sailing with my family aboard our 40 Woods Meander catamaran - traveling from B.C.'s north coast, to the west coast of the US, Mexico, the South Pacific, Australia, New Zealand, South East Asia, across the Indian Ocean to South Africa and on to St Helena, South America, the Caribbean and Central America.

2 replies on “What “good” bridgedeck clearance is and why is it important? – Richard Woods Interview # 4”

Dear Richard and Catamaransite.

Thanks for this article. Do you have actual measurements of bridgedeck heights for the most popular mass produced cats? (Eg Lagoon 40, Nautitec 40 Open, FPS etc). Either “empty” or with a reasonable weight on board? I wonder why it is not standard practice in reviews to indicate it, given the importance.

I think it’s important, but over the last 10 years I’ve looked for this info and find it’s scarce, which is why you don’t see this in our “Brands” section. In speaking with catamaran designers, bridgedeck clearance is only one factor of many in determining catamaran performance, and again, only one of many factors to take into account when considering catamaran comfort. All boat designs are a compromise as designers balance design criteria. Also, depending how the boat is used changes priorities. Bridgedeck clearance will probably be at the top of the list if you’re circumnavigating, and at the bottom of the list if you’re cruising. (Cruising boats spend 99% of their life at anchor or at the dock). So … it depends..

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Bridgedeck Clearance

The space between, an in-depth look at bridgedeck clearance for catamarans.

– By Sackville Currie of Multihull Design

Bridgedeck clearance (the height of the bridgedeck above the water) is crucial for catamaran’s seaworthiness and crew comfort. Because bridgedeck clearance can be seen at a glance, and is easily measured, even an inexperienced sailor can evaluate it.

Why does a catamaran need high bridgedeck clearance? First, ocean waves need headroom to pass between the hulls. Second, each bow creates a bow wave; these V-shaped waves meet under the bridgedeck and increase the clearance needed. What happens when bridgedeck clearance is inadequate? The one-word answer: Pounding. Visit our article on bridgedeck clearance on catamarans to see a video explanation of the importance of bridgedeck clearance by Stephen of Catamaran Guru as well as a video between the hulls of a Lagoon 450S in heavy following seas with moderate gale force winds.

Pounding causes three problem areas:

• to the crew: physical discomfort, and fatigue
• to the boat and rig: excessive wear and tear (I’ve had multihull design bulkheads break from windward pounding)
• and to the boat speed: a serious reduction.

The potential of the catamaran hull form, which is so impressive when sailing at 8 to 10 knots in 20 knots of breeze in protected waters, can be quickly reduced to 5 knots by pounding. Yes, a very low bridgedeck cat can lose 3 to 4 knots of boat speed with a major pound.

Read more about bridge deck clearance .

Estelle Cockcroft

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2 thoughts on “Bridgedeck Clearance”

It is all about steering so you get the right angle of the waves to your hull. I did own a Fountaine Pajot Tobago. Infamous for its low bridgedeck clearance. But I crossed the Atlantic with her twice and no poundung whatsoever. Doing 15kts. And waves of 15ft.

The angle of the dangle, as they say. Yes, you are correct and most cats will slam if you go straight into the waves.The short steep chop in the Chesapeake is notorious for exactly that! LOL

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Nearly month after Key Bridge collapse, recreational boats can use temporary channel on Sunday

B ALTIMORE — Recreational boats will again be allowed to pass the site of the Francis Scott Key Bridge collapse, this time on Sunday, marking the second opportunity for boaters since the bridge fell three weeks ago.

The Coast Guard said recreational vessels will be able to use the Sollers Point Alternate Channel again, but this time officials will accommodate one-way traffic both into and out of the harbor during two separate 45-minute periods in the morning and two in the evening.

A first round of boats were allowed to use the alternate channel on Tuesday during two hourlong stretches, one in the morning and one in the evening. More than 35 recreational vessels like sailboats and yachts took advantage of the chance to relocate their boats into and out of Baltimore’s harbor, whether bringing in vessels for the summer season or departing for another destination.

On Sunday, from 6:30 a.m. to 7:15 a.m., recreational boats can use the Sollers Point temporary channel to depart the harbor. From 7:15 a.m. to 8 a.m., recreational vessels will be allowed to flow into the harbor, according to a notice from the Coast Guard.

In the evening, outbound vessels will be allowed to transit from 6 p.m. to 6:45 p.m., and inbound boats will transit from 6:45 p.m. to 7:30 p.m.

Until this week, traffic around the Key Bridge had been closed to recreational boats, with alternate channels reserved for commercially essential vessels that are helping to clear the wreckage.

The 1.6-mile bridge fell into the Patapsco River on March 26 after it was struck by a container ship. Six construction workers died in the collapse, which has also hampered traffic to and from the Port of Baltimore. The Army Corps of Engineers hopes to restore access to the port by the end of May.

Port officials opened a third temporary shipping channel on the northeast side of the fallen Francis Scott Key Bridge on Friday.

The final of three alternative paths for boats around the wreckage of the bridge has a depth of about 20 feet and will allow “limited access for commercially essential vessels,” according to a Key Bridge Unified Command news release. The newest channel has a 300-foot horizontal clearance and a 135-foot vertical clearance.

©2024 The Baltimore Sun. Visit at baltimoresun.com. Distributed by Tribune Content Agency, LLC.

Third temporary channel opens for vessels to Baltimore port after bridge collapse

BALTIMORE — A third temporary channel for boats to enter and depart the Port of Baltimore has opened, expanding further shipping access as collapsed sections of the Francis Scott Key Bridge are salvaged before the span can ultimately be rebuilt.

The alternate channel, located to the northeast of the fallen bridge, is open to “commercially essential vessels,” port officials announced late Friday.

The new temporary path, with a controlling depth of 20 feet (6.1 meters), a horizontal clearance of 300 feet (91.4 meters) and a vertical clearance of 135 feet (41.2 meters), allows a greater variety of vessels to access the port while crews work to reopen the main channel, Coast Guard and port Capt. David O’Connell said in a news release.

With the new channel open, about 15% of pre-collapse commercial activity will resume, O’Connell said. The first temporary channel opened April 1. The bridge collapsed early March 26 after it was struck by the cargo ship Dali.

Officials hope to open a channel by the end of the month to allow most maritime traffic back into one of the East Coast’s busiest maritime transit hubs.

Workers are laboring to remove thousands of tons of debris sitting atop the Dali , the cargo ship that veered off course and struck the 1.6-mile-long (2.57-kilometer-long) bridge. Six roadwork crew members on the bridge died. Two of their bodies have not been found.

With massive cranes, workers so far have taken away about 1,300 tons (1,179 metric tons) of steel. The debris on the stationary ship must be removed before the vessel can be returned to the port.

Boat gets stuck while trying to pass over Portage Lake Bridge

HOUGHTON & HANCOCK, Mich. (WLUC) - If you traveled across the Portage Lake Bridge in Houghton on Saturday morning, you probably experienced some delays.

A TV6 reporter passing over the bridge saw a boat stuck on one of the beams while trying to cross from Houghton into Hancock.

Hancock City Police said the driver misjudged how much clearance there was. Thankfully, no one was hurt and the driver was able to remove the top railing from the boat and continue driving.

Cars in the northbound lane from Houghton experienced some delays.

Copyright 2024 WLUC. All rights reserved.

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Inland bridge clearence

• Thread starter gatekeeper236
• Start date Nov 7, 2009
• Forums for All Owners
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gatekeeper236

Can anyone tell me if a 53.6 mast will clear bridges along Tenn/Tom and Tenn river as on a H33.5 or do I need to stay with the H34 with a mast of 51.6 not sure yet which boat to get  

get the NOAA map not sure where that is. NOAA has raster maps that have bridge clearances. you can use the SeaClear program to view them. use Google to find both. NOAA maps http://www.nauticalcharts.noaa.gov/mcd/Raster/download_agreement.htm seaclear http://www.sping.com/seaclear/  

Have tried that. NOAA just takes me to Mobile Bay and inland maps of Tenn. river have all clearances on reverse side which dont show up and not ready to purchase charts as of yet maybe if I print them out?  

Henry Scurlock

There is a bridge clearance listing at this site http://tinyurl.com/yho2dyq  

Thanks Henry that worked and answered my Question! 52' it is  

Lots of concerns with river levels as well. Lots of rain up river, less clearance...drought, lot of clearance above boat, but not below.  

Jerry Clark H356 SV Persi

Tenn Tom Bridge Clearance - neither will probably work First, your mast height is probably not either of those numbers as Hunter's specs take you to the top of the actual mast -not including the light, wind instruments, and antenna. My H356 has a 55'-3" spec "mast height", but is actually 58.69 feet to the tip of the vhf antenna and to clear the light and raymarine wind instrument it is 56.91 feet - that bends the vhf antenna which will likely snap against your wind instrument and will definitely take out your windex (mine was gone within 3 weeks of buying my boat in 03). I've been down the Tenn-Tom (in a Cabo Rico 38 with the mast up) and there are flat bridges that are listed at 52 feet we cleared the vhf anteena by 2 inches. There are arch bridges that are listed as 52 feet and that is to the low steel at the side of the bridge. I have had mixed answers about whether it is clearance to the light (hangs down about a foot or more) or the structural steel. You should measure both ACCURATELY by survey or by going up the mast and dropping a tape down. Most at KY Lake take the mast down and re-step in Mobile. It's not that big a deal to do that and I wouldn't buy my boat based on that as a limitation if I were you. I have a spreadsheet that has all the mast clearances for all the bridges down the Tenn-Tom. You also need to adjust them each day for the actual water heights and there is a link on my spreadsheet that shows where to get the information and then you must manually enter it. If you want the spreadsheet, I will e-mail it to you if you post your e-mail. It worked for us in the Cabo Rico. You will need to also enter your own specific mast heights - including the lights, wind, etc.for it to work properly. I have attached two pdf files - one is the listing of the bridges from the Tenn-Tom chart book. The other is the 356 mast from base to antenna, etc. - IT DOES NOT INCLUDE THE BASE TO WATER DIMENSION WHICH MUST BE ADDED!  

Attachments

• Bridges on Tn Tom and Clearance Normal pool.pdf 52.5 KB Views: 919

Seconfd file too large to load! Photos of the top of my mast before stepping were too large to load. I will e-mail to you if you want the information on the dimensions of the stuff on top of my mast.  

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