Posting Rules | post new threads post replies post attachments edit your posts is are code is are are are | Similar Threads | Thread | Thread Starter | Forum | Replies | Last Post | | Nomad57 | Dollars & Cents | 6 | 02-07-2011 08:07 | | capt.cam | Dollars & Cents | 10 | 11-05-2011 21:30 | | labaxter | Monohull Sailboats | 21 | 18-08-2010 15:25 | | CaptainBW | Monohull Sailboats | 7 | 11-08-2010 15:06 | | ribbony | General Sailing Forum | 4 | 13-03-2006 19:11 | Privacy Guaranteed - your email is never shared with anyone, opt out any time. Great choice! Your favorites are temporarily saved for this session. Sign in to save them permanently, access them on any device, and receive relevant alerts. Tartan 34 CTartan 34 C is a 34 ′ 4 ″ / 10.5 m monohull sailboat designed by Sparkman & Stephens and built by Tartan Yachts between 1968 and 1978. Rig and SailsAuxilary power, accomodations, calculations. The theoretical maximum speed that a displacement hull can move efficiently through the water is determined by it's waterline length and displacement. It may be unable to reach this speed if the boat is underpowered or heavily loaded, though it may exceed this speed given enough power. Read more. Classic hull speed formula: Hull Speed = 1.34 x √LWL Max Speed/Length ratio = 8.26 ÷ Displacement/Length ratio .311 Hull Speed = Max Speed/Length ratio x √LWL Sail Area / Displacement RatioA measure of the power of the sails relative to the weight of the boat. The higher the number, the higher the performance, but the harder the boat will be to handle. This ratio is a "non-dimensional" value that facilitates comparisons between boats of different types and sizes. Read more. SA/D = SA ÷ (D ÷ 64) 2/3 - SA : Sail area in square feet, derived by adding the mainsail area to 100% of the foretriangle area (the lateral area above the deck between the mast and the forestay).
- D : Displacement in pounds.
Ballast / Displacement RatioA measure of the stability of a boat's hull that suggests how well a monohull will stand up to its sails. The ballast displacement ratio indicates how much of the weight of a boat is placed for maximum stability against capsizing and is an indicator of stiffness and resistance to capsize. Ballast / Displacement * 100 Displacement / Length RatioA measure of the weight of the boat relative to it's length at the waterline. The higher a boat’s D/L ratio, the more easily it will carry a load and the more comfortable its motion will be. The lower a boat's ratio is, the less power it takes to drive the boat to its nominal hull speed or beyond. Read more. D/L = (D ÷ 2240) ÷ (0.01 x LWL)³ - D: Displacement of the boat in pounds.
- LWL: Waterline length in feet
Comfort RatioThis ratio assess how quickly and abruptly a boat’s hull reacts to waves in a significant seaway, these being the elements of a boat’s motion most likely to cause seasickness. Read more. Comfort ratio = D ÷ (.65 x (.7 LWL + .3 LOA) x Beam 1.33 ) - D: Displacement of the boat in pounds
- LOA: Length overall in feet
- Beam: Width of boat at the widest point in feet
Capsize Screening FormulaThis formula attempts to indicate whether a given boat might be too wide and light to readily right itself after being overturned in extreme conditions. Read more. CSV = Beam ÷ ³√(D / 64) S&S Design No. 1904. The letter “C” has been adopted on the used boat market, “classic”, identifying it as the first 34 from Tartan. The second TARTAN 34, which is also a S&S design, is commonly referred to as the TARTAN 34-2. There was an option (rarely selected) to substitute a pilot berth for the cabinet storage to port, over and outboard of the dinette. The foot of the mainsail was shortened from the original design at least twice to improve balance and/or to lower it’s IOR rating. Hull 125 and later: E = 12.0’ Hull 200 and later: E = 10.5’ (displayed here) A yawl rig was advertised as an option. Embed this page on your own website by copying and pasting this code. Discover Related SailboatsCruising World: 40 Best Sailboats©2024 Sea Time Tech, LLC This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. What Do Boat Measurements Mean? 11 Terms Explained!Boat measurements are crucial for maritime safety, efficiency, and compatibility. Navigating these measurements is vital for manufacturers and boating enthusiasts. Proper understanding ensures vessel selection, marina compliance, and safe navigation. 11 Main Boat Measurement Terms- Length Overall (LOA) : The total length from the bow to the stern. It determines mooring space, marina fees, and navigation in confined waters. For example, a boat with a 30-foot LOA needs a slightly longer berth.
- Length on Deck (LOD) : Measures the hull’s horizontal length, excluding extensions like bow sprits. It provides a more accurate measurement of usable space. A boat might have a 35-foot LOA but a 30-foot LOD due to a 5-foot bow sprit.
- Beam : The width at the widest point, affecting stability and maneuverability. For instance, a boat with a 10-foot beam is more stable but less maneuverable than one with an 8-foot beam.
- Draft : The minimum depth required for the boat to float. A sailboat with a 6-foot draft cannot navigate waters less than 6 feet deep.
- Displacement : The weight of water displaced by the hull, reflecting the boat’s weight when loaded. A boat displacing 5 tons handles differently than one displacing 2 tons.
- Freeboard : The distance from the waterline to the upper deck, indicates how much of the boat is above water. A boat with 4 feet of freeboard handles choppy water better than one with 2 feet.
- Deadrise : The hull’s angle relative to a flat surface. A higher deadrise (sharp angle) cuts through waves better. A boat with a 20-degree deadrise performs better in rough water than one with a 10-degree deadrise.
- Air Draft : The height from the waterline to the highest fixed point. Important for bridge clearances. A sailboat with a 50-foot mast must consider bridge heights.
- Gross Tonnage : Volume measurement for large vessels, based on total internal space. For example, a cargo ship with 50,000 gross tonnage has a large capacity.
- Ballast : Weight added low in the boat for stability. A sailboat with 2,000 pounds of ballast is more stable than one with 1,000 pounds.
- Waterline Length (LWL) : Length at the waterline, affects speed and stability. A boat with a 25-foot LWL is generally faster than one with a 20-foot LWL.
How to Measure a Boat Hull- Length Overall (LOA) : Measure from the furthest point forward to the furthest point aft.
- Length on Deck (LOD) : Measure the deck length, excluding overhangs.
- Waterline Length (LWL) : Measure at the waterline.
- Beam : Measure the widest part of the hull.
- Draft : Measure from the waterline to the lowest part of the hull.
- Freeboard : Measure from the waterline to the upper edge of the hull.
- Deadrise : Measure the angle between the hull bottom and a horizontal plane.
- Hull Depth : Measure from the deepest point of the hull to the top of the deck.
Coast Guard Boat Length MeasurementThe U.S. Coast Guard measures boat length using the Length Overall (LOA) method, from the bow’s tip to the stern’s end, including structural parts but excluding removable attachments. This measurement is crucial for regulatory and safety reasons, influencing boating laws and safety requirements. - Responsibilities of a Fourth Engineer on Cargo Ships – September 10, 2024
- The Role of Cargo Ships in Global Trade – August 22, 2024
- Report: Yang Ming’s YM Mobility Explosion at Ningbo-Zhoushan Port – August 9, 2024
About the author I worked as an officer in the deck department on various types of vessels, including oil and chemical tankers, LPG carriers, and even reefer and TSHD in the early years. Currently employed as Marine Surveyor carrying cargo, draft, bunker, and warranty survey. Latest postsIs Maritime Security Necessary on Modern Ships?It’s vital for ships to stay vigilant. Isolation from land means having no backup or protection for miles, making them vulnerable to attacks and other threats. Equip modern ships using modern maritime security methods. Responsibilities of a Fourth Engineer on Cargo ShipsA Fourth Engineer on cargo ships oversees engine room operations, machinery maintenance, and ensures compliance with regulations like MARPOL. The Quality Control Process in Marine ManufacturingCompanies in the marine manufacturing space must have tight and effective quality control processes. What steps should an effective quality control process include? Need a boat to Pass Under a Bridge? When passing under a bridge with your vessel, there are various things that you will need to take into consideration, some of these being the air draft and bridge’s clearance. Air Draft is a term found on the specification chart for most boats and is a measurement that could be very important when purchasing your boat. A vessel’s draft is the distance measured between the top of a vessel’s highest point to its waterline. Vertical clearance is the distance above the air draft that allows the vessel to pass safely under a bridge. Failing to consider air draft may result in being unable to calculate a vessel’s vertical clearance during a passage can be catastrophic. A bridge’s clearance can be found displayed on charts as measured from the surface of the water to the underside of the bridge at Mean Highest High Water, which is the most restrictive clearance. The Mean Higher High Water (MHHW) is the average height of the highest tide recorded at a tide station each day during the designated recording period. It is used to measure the navigational clearance, or air draft, under bridges so that vessels can pass through safely. For our MAKAI M37 Power Catamaran the air draft, as measured from the waterline to the top of the roof is 3130mm which is 10ft 3in. The loaded waterline is the point on the hulls where the water reaches the boat loaded with fuel, water and other small items such as safety equipment. If you have any other questions, we are always up for a chat and a challenge! Contact us today to find out more about our vessels and any other enquiries you may have. Follow us on Facebook and Instagram to stay up to date with all the latest news on Makai Yachts. - Get Newsletter
- Privacy Policy
https://calendly.com/makaiyachts/makai-m37-boat-tour?month=2024-08 What is a Ship’s Air Draft and How to Best Calculate ItA ship’s air draft, sometimes called air draught, is an important measurement to consider when planning a voyage. It is one of the factors seafarers check if their vessel can safely navigate within harbors where suspended obstacles are present. While the regular draft and under keel clearance (UKC)... https://www.seamanmemories.com/ships-air-draft/ Leave a Comment Cancel replySave my name, email, and website in this browser for the next time I comment. Subscribe To Our Newsletter - Forums New posts Unanswered threads Register Top Posts Email
- What's new New posts New Posts (legacy) Latest activity New media
- Media New media New comments
- Boat Info Downloads Weekly Quiz Topic FAQ 10000boatnames.com
- Classifieds Sell Your Boat Used Gear for Sale
- Parts General Marine Parts Hunter Beneteau Catalina MacGregor Oday
- Help Terms of Use Monday Mail Subscribe Monday Mail Unsubscribe
Air draft and ICW bridges- Thread starter captron
- Start date Aug 29, 2017
- Forums for All Owners
- Ask All Sailors
In theory would this work (I don't think I would have the nerve to try it ) I have a Legend 40.5 if I see the tide boards reading 64 ft of clearance I will "ding" my vhf antenna on the bridge girders ,at 1800 rpm I'm cruising at 7 knots with a Flex-O-Fold 3 blade prop which at that speed and rpm will cause the stern to squat a good 6 inches at 2000 rpm maybe about 8 inches (can you say over propped) ??? my question in theory.......with the stern squatting 6 to 8 inches would that reduce the air draft???? look forward to your replies Capt. Ron Captain Larry-DHYes, in theory. It would increase your aft-leaning angle, and assuming your mast is stepped somewhere just forward of amidships, the deck level should not be raised by the bow wave. My question: Do you feel so confident in the accuracy of tide boards and tide tables that you'd risk your mast by making a 7-knot approach with little margin for error? I'd creep up on it if it was close. Larry, That's what I do.............."sneak up on it" Have not worked out the math but it seems to me that a squat of 6 inches at the stern would only translate perhaps as 2 inches at the mast at best. There are other factors like for how long can the boat hold the squat before its depth starts decreasing. The strength and direction of currents will also influence the depth of the squat. I think at best is a poor gamble; the tried and true methods are to plan arrival and approach at low tide or to heel the vessel. We are always checking air draft. With speed we ride up on the bow wave being higher in the water. Yes we've bent antennas and anchor lights. Going slow we clear at our desired height. All U Get All U Get said: We are always checking air draft. With speed we ride up on the bow wave being higher in the water. Yes we've bent antennas and anchor lights. Going slow we clear at our desired height. All U Get Click to expand Please notify us when and where you plan to try this method CR. I'll sail over to watch! If I had to cheat on air draft, I'd be more likely to run my main halyard over to my tender that I had a fat boy run along side the boat & try to pull the sailboat over into a little bit of a heal with the weight of the tender. I would need a good reason to try even this trick. Waiting for proper tide would still be my first choice. If you are going to try that other trick, you might want to invest in some nylon bolts to mount your antenna with. Spare nylon bolts are cheaper than antennas. SBO Weather and Forecasting Forum Jim & JohnGgrizzard. If you go take pictures. This could be a viral YouTube video in the making. Maybe American Home Video entry. They have a 100,000 grand prize. I'm on it! I have 64.5 draft, went from NC to FL, made them all but scrap ant. several times and always went thru questionable ones on low tide, (had to wait 3 times, couple hours at most) even pulled up to the fenders and walked to boat thru. It seems to me if the stern is squatting, with the mast forward of the moment it might actually lift a little. I went thru the dismal swamp with a reported 64 ft bridge (there is no tide in the canal and the Corp of Engineers keep the level to around 6 ft deep). I have a 63' 4" clearance to the top of the wind instrument, I also have a 3 ft vhf antenna and a 4 ft SSB/DSC antenna. Going under the 64 ft bridge was a nail bitter (remember not tide or wake to worry about - sort off). The metal antennas scrapped the bottom of the bridge. I lost the bird spike on the wind vane because it was hit by one of the antennas. One of the unknowns and my concern is when you are under the bridge and a wave/wake hits your boat you may bounce and hit the bottom of the bridge. I continued all the way to Miami with a couple of nail bitters/scraping the bottom of the bridges with antennas. I did go out from FLL to Government cut because there is a fix bridge in between FLL and Mia. The worse case was a bridge in Fl that had a 6 inch difference between hi and lo tide and no high board. Velero49 said: I went thru the dismal swamp with a reported 64 ft bridge (there is no tide in the canal and the Corp of Engineers keep the level to around 6 ft deep). I have a 63' 4" clearance to the top of the wind instrument, I also have a 3 ft vhf antenna and a 4 ft SSB/DSC antenna. Going under the 64 ft bridge was a nail bitter (remember not tide or wake to worry about - sort off). The metal antennas scrapped the bottom of the bridge. I lost the bird spike on the wind vane because it was hit by one of the antennas. One of the unknowns and my concern is when you are under the bridge and a wave/wake hits your boat you may bounce and hit the bottom of the bridge. I continued all the way to Miami with a couple of nail bitters/scraping the bottom of the bridges with antennas. I did go out from FLL to Government cut because there is a fix bridge in between FLL and Mia. The worse case was a bridge in Fl that had a 6 inch difference between hi and lo tide and no high board. Click to expand jssailem said: Ggrizzard. If you go take pictures. This could be a viral YouTube video in the making. Maybe American Home Video entry. They have a 100,000 grand prize. Click to expand ggrizzard said: Please notify us when and where you plan to try this method CR. I'll sail over to watch! Click to expand Ok, I said in theory, I didn't say I was going to try it....... I know some of you will be disappointed to hear that. Regards Capt. Ron For us, the boat IS the family pet. - This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register. By continuing to use this site, you are consenting to our use of cookies. Accept Learn more…
Log in or Sign upYou are using an out of date browser. It may not display this or other websites correctly. You should upgrade or use an alternative browser . Zud Senior MemberOkay you gurus of Yachting, Easiest/accurate method of determining required air draft short of driving under the bridge and measuring the amount torn off of the mast/radar arch. Boat literature makes no sense...20'8" with TV dish removed but the light mast with radar is considerably higher on the boat and would be required/original equipment. How do I get a good measurement from top of radar arch to water level with all electronics removed?? Thanks Zud olderboater Senior MemberYes, the literature is useless. Others will have other ideas I'm sure, but here's how we did it. We measured a boathouse height from the water. Pulled the boat in, measured clearance. So our air draft was the height of the boathours opening less the amount we cleared it by. You can do the same under bridges that have accurate markings, note the word "accurate" as some don't, so I'd select more than one to check. We've double checked our boathouse numbers with bridges. Just as you need to know draft at different loads, make sure you take loads into account on air draft. This in addition to knowing it with all different equipment and height permutations. Capt J Senior MemberJust lay a fishing rod across the hardtop where you can lay the rod verticle with a bobber on it and drop it down till it hits the water, then take it on land and measure it......if something sticks up above the hardtop measure that from the hardtop to the highest point and add to your measurement. I knew I could count on you guys !!! easiest and as accurate as need be. Will do ASAP Oscarvan Senior MemberFor RV's I use a laser level and large telescoping height pole. (Home Depot or Lowes) C4ENG Senior MemberCould you use your docking plan or general arrangement drawings to calculate the air draft while using a pair of dividers and the measuring scale on the drawing for the vessel and then add it all up? Pascal Senior MemberHome Depot sells measuring tapes.... J, Some of us don't fish and may not have fishing gear... You can still measure the boat, first from WL to deck, then the house, then the hard top or whatever. I thin measuring tapes are cheaper than a fishing rod and line, and lead most smart phones come with free calculator app so you can add up the various measurements Pascal said: ↑ Home Depot sells measuring tapes.... J, Some of us don't fish and may not have fishing gear... You can still measure the boat, first from WL to deck, then the house, then the hard top or whatever. I thin measuring tapes are cheaper than a fishing rod and line, and lead most smart phones come with free calculator app so you can add up the various measurements Click to expand... not a single fishing rod on this boat ... Hoping to keep it this way - No, create an account now.
- Yes, my password is:
- Forgot your password?
|
COMMENTS
Air draft (or air draught) is the distance from the surface of the water to the highest point on a vessel. This is similar to the deep draft of a vessel which is measured from the surface of the water to the deepest part of the hull below the surface. However, air draft is expressed as a height (positive upward), while deep draft is expressed ...
Air draft (draught) is a term used to describe the distance from the top of a vessel's highest point to its waterline. Vertical clearance is the distance in excess of the air draft that allows a vessel to pass safely under a bridge or object. The consequences of failing to consider air draft and to properly calculate a vessel's vertical ...
Air draft is the total distance from water level to the top of the tallest equipment attached to the mast head. When going under bridges, it's important to ...
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 ...
A boat's draft refers to the vertical distance between the waterline and the deepest point of the vessel's hull. It represents how much of the boat is in the water. Measured in feet or meters, the draft is a critical specification for boat designers, manufacturers, and mariners alike. It is crucial in determining a boat's stability ...
The one absolute and immutable dimension for the Great Loop is an air draft of 19 feet, 6 inches, in order to clear the fixed Chicago railroad bridge. Of course, you can also complement your Loop experience with air drafts of 17 feet (downtown Chicago) or 15 feet, 6 inches (the Erie Canal). Air draft is arguably the most important dimension ...
The lower the ratio the greater the boat's stability. Carlin - similar to a beam, except running in a fore and aft direction. ... Draft, Air - Air Draft/Draught is the distance from the water line to the highest point on a ship (including antennas) while it is loaded. Air draft is the minimum height a ship needs to pass under, while ...
Performance air draft: 18.78m / 61.58ft Performance rig: I - 15.65m / 51.33ft J - 4.78m / 15.67ft P - 15.40m / 50.5ft ... it will vary with the weights of fuel, water, stores and equipment. A boat's actual draft is usually somewhat more than the original designed or advertised draft. For boats with adjustable keels (centerboards, daggerboards ...
Air Draft refers to the vertical distance between the waterline and the highest point of a vessel, typically measured from the waterline to the top of the highest mast, antenna, or structure on board. It represents the maximum height that a vessel can safely navigate under bridges, power lines, or other overhead obstacles without risking ...
Air draft explained. Air draft (or air draught) is the distance from the surface of the water to the highest point on a vessel.This is similar to the deep draft of a vessel which is measured from the surface of the water to the deepest part of the hull below the surface. However, air draft is expressed as a height (positive upward), while deep draft is expressed as a depth (positive downward).
Second, the boat you choose must have an air draft of less than 19.6 feet so it can clear the lowest fixed bridge on the Great Loop, which is located on the Illinois Waterway and cannot be bypassed by taking an alternate route. ... She is a regular speaker about the Great Loop at events like the Miami Boat Show, Chicago Boat Show, TrawlerFest ...
Draft/Shoal 7' 6" / 6' 0" Air Draft 74' 9 ... Sailing sailboats Top 10 Nominee boat review. By. Zuzana Prochazka. SAIL Charter Editor Zuzana Prochazka is a USCG 100-ton master who logs countless miles on all kinds of boats around the world and never misses an opportunity to raise a sail or crawl into the engine room of a new design ...
However, we checked one boat from a third builder. Their numbers were from the most optimistic view. Their quoted air draft was from a fully loaded boat in every way and several inches less than the draft we found in our worst case. Their water draft was less than we found in any load situation. They quoted 5'. Out numbers ranged from 5'1" to 5'3".
Meri has an air draft of 63ft 4in and her keel draws 5ft 4in, so going all the way on the ICW was certainly an option. We'd also made two crossings to the Bahamas and back that winter, which meant we now had some offshore experience as well. Still, we were not yet comfortable with making a long passage, so on this trip we decided to restrict ourselves to offshore jumps of less than 250 miles.
Most sailboats will need to unstep the mast to clear the bridges outside of Chicago and upstate New York. Your choice of waterways through New York State and into Canada will also be dependent on your air draft. If you can clear a 15' bridge, you have the option to take the Erie Canal to its western terminus into Lake Erie. If you can clear a ...
Re: Maximum draft for cruising the Atlantic ICW. Going aground I feel is more about your level of risk taking than the draft of your boat. If 1 foot of extra draft is really going to be limiting ask yourself how often you would be willing to sail with 1 foot of water clearance. My first boat was 5'2" and my current boat is 6'4" draft.
Air Draft 44 ′ 2 ″ / 13.5 m ... Sail area in square feet, derived by adding the mainsail area to 100% of the foretriangle area (the lateral area above the deck between the mast and the forestay). D: Displacement in pounds. 16.85 <16: under powered.
With weight variability boat to boat, I wouldn't buy a boat without measuring air draft if that's a critical factor for you. I like Raked's adding 10 feet to the measurement for real bridge clearance. All it takes is one wake while transiting to drop the rig if it's close. P . Last edited by a moderator: Oct 23, 2013.
A higher deadrise (sharp angle) cuts through waves better. A boat with a 20-degree deadrise performs better in rough water than one with a 10-degree deadrise. Air Draft: The height from the waterline to the highest fixed point. Important for bridge clearances. A sailboat with a 50-foot mast must consider bridge heights.
It is used to measure the navigational clearance, or air draft, under bridges so that vessels can pass through safely. For our MAKAI M37 Power Catamaran the air draft, as measured from the waterline to the top of the roof is 3130mm which is 10ft 3in. The loaded waterline is the point on the hulls where the water reaches the boat loaded with ...
The boat can be sailed entirely from the twin helms aft or from the optional interior steering position. The twin helms are two steps up from the regular cockpit floor. ... LOA 50'7" LWL 45'4" Beam 15'11" Draft 7'1" Air Draft 79' Displacement 46,650 lbs Ballast NA Sail Area 1,409sq ft (main and jib) Power Yanmar 110hp or 150hp ...
7 November 2023. A ship's air draft, sometimes called air draught, is an important measurement to consider when planning a voyage. It is one of the factors seafarers check if their vessel can safely navigate within harbors where suspended obstacles are present. While the regular draft and under keel clearance (UKC)... https://www ...
Jeanneau 45.2 Saugatuck, MI. Aug 30, 2017. #11. I have 64.5 draft, went from NC to FL, made them all but scrap ant. several times and always went thru questionable ones on low tide, (had to wait 3 times, couple hours at most) even pulled up to the fenders and walked to boat thru.
Pulled the boat in, measured clearance. So our air draft was the height of the boathours opening less the amount we cleared it by. You can do the same under bridges that have accurate markings, note the word "accurate" as some don't, so I'd select more than one to check. We've double checked our boathouse numbers with bridges.