As mentioned above, the operation of the propeller relies on the transom height. Add the two measurements and you get 6 1/2". If youd like to see this in video format, skip to 0:44 in the below YouTube Video: Is it OK to put a long shaft outboard on a boat thats rated for a short shaft? Then open up the clamp bucket. Offshore vessels are often equipped with a large mounting bracket so that the transom can be left at full height. A: The short answer is Yes. Disclaimer: As an affiliate I may earn a commission on any qualifying purchases, including those from Amazon.com, at no extra cost to you read more. The propellers will also have trouble reaching the water. What the relationship to the pontoons is, I couldn't say. stream If you have a short shaft motor, the distance between the top of the transom and the bottom of the boat should be between 15 and 16 inches. s.setAttribute("rel", "stylesheet"); I would also recommend finding your maximum horsepower rating which is located on the yellow coast guard tag towards the back of your boat. boats.com is part of the Boats Group Network. The flat part of the bracket that rests on the transom when mounted will give you the same point of reference as the transom does on the boat. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. As a result, the issue is whether my boat need a short shaft or long shaft motor. Its still smart to measure it yourself though, just in case, the design changed over the years. The greater the number, the more the drive may sway (also called tuck under or negative trim). How do you measure a transom on an outboard motor? Your goal is to measure how the outboard will sit, so start from the clamping plate and follow the centerline of the hull. Tightening Torque for Engine. If you have a question or need additional information,contact ustoday. Mounting the outboard motor in accordance with the industry standards is important. Assistant Measuring tape Grease pencil Ask a friend to hold one end of a measuring tape at the extreme outer edge of the top of the transom while you pull the tape across its width to the opposite outer edge to measure the "length of the taffrail," which is the width of the boat across the top edge of the stern. One of the main concerns is causing the engine to overheat if not enough water reaches the engine to keep it cool. Measure from the top of the transom to the bottom of the hull. How-To: Pick A Great Portable Outboard Motor (2023 Guide) This is a measurement that has been used for BassCats, I'm from the transom. Actual shaft length is 21.5" on those. var addyd53b59933f6c3f2e8b59f1b4a6d41fa5 = 'info' + '@'; Say the 20 shaft is a long shaft length for gas engines, but it is a short shaft length for electric outboard motors. <>/Metadata 127 0 R/ViewerPreferences 128 0 R>> Higher mounting decisions should be left to the professionals. Allowing the propeller to pull water from underneath and push it out behind the boat. endobj The cavitation plate is the horizontal surface of the lower unit immediately above the propeller. The cookie is used to store the user consent for the cookies in the category "Analytics". As a dealer I don't really like hearing this because there is a chance it could go either way and you have to get it right. Boat hulls are designed in three basic types that range from slow displacement and semi-displacement hulls to the fastest planing hulls. 1855 Alpine Avenue NWGrand Rapids, MI 49504This email address is being protected from spambots. s = d.createElement("link"); If it measures 15" or with in a inch of that you will need a short shaft outboard. August 9/08). Why Rebounding Is A Key Skill for Fouth Players To Learn, Tips For Attacking a Zone Defense as a Youth Basketball Team, Why This is a Big Deal for the Sports Betting Industry. Measure from there down to the top of the cavitation plate, also known as the anti-ventilation plate. I run a 9.9 Mercury Bigfoot 20" shaft off the swim platform of my 89 Trophy 2160. This, however, is not recommended for the beginning boater. % The first order of business is to measure your boat for the ideal fit. Cavitation plates are used on the bottom components of boats to help them operate better. The height of the transom is calculated by measuring from the bottom of the hull to the top of the transom, using the center line. <>/ExtGState<>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 595.2 841.8] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> Installing a Kicker Motor Bracket - Gone Outdoors motor brackets With the outboard shaft length too long, meaning the prop is too deep in the water, the engine wont be as efficient, and the fuel burn is high. Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. Buying a boat can be an exciting purchase. If it measures 15" or with in a inch of that you will need a short shaft outboard. Some fishing boats can handle the motor being underwater. Owners of bass boats, RIBs, or offshore fishing boats need to get this right. If you decide to make some custom adjustments we have theexperience and know-howto make it happen. Actually there is no designated letter for short shaft. It varies between different motors and boats. Here are several situations on how you should adjust the outboard shaft length: Mounting the outboard a little bit higher than the standard point could reduce drag, improve RPM at full throttle, and therefore improve speed and make it easier for the boat to get on plane. Now that you have a better understanding of boat transom heights its time to take out the ruler and get the perfect measurements. Now that you have a better understanding of boat transom heights its time to take out the ruler and get the perfect measurements. My family and I used it to fish, ski (yes, you can ski behind a pontoon boat), and cruise the lakes near our home. With it comes a lot of responsibility and new things to learn including boat maintenance and boat basics. What's the best height for my boat motor? The cookie is used to store the user consent for the cookies in the category "Performance". Each one has a totally different effect on the boats performance. manufacturer will recommend the outboard height according to the bracket shape and length. In step 3, add another 10 cm (4") to the previous calculation in order to develop the ideal shaft length. xmlHttp.open('POST', 'https://bes.gcp.data.bigcommerce.com/nobot'); How to Measure a Boat Transom - Gone Outdoors The point where these measurements intersect is your centerline. (Putting a It also includes attaching the right engine. They operate as a planing surface, allowing your boat to climb to the top more quickly. Another important measurement is the transom angle. Rest the yard stick or another suitable straight edge along the keel on the bottom of the boat so that it makes a straight line aft to the outboard. If it measures between 17 and 22, youll want to go with a long shaft motor. Here we will guide you in how to get the right boat transom height. The anti-cavitation plate above the prop needs to be within an inch of the bottom of the transom, therefore, the prop should be well below the transom. Plus, a low transom cut is an invitation for the water to flood the boat. When the right length motor is hung on the transom of a boat, the cavitation plate (the large plate that extends out over the propeller) should be even with the very bottom of the boat. If we run into that scenario, I would still show you the different options of motors and go over pricing, but I would also ask you to hold off and do one thing before you pull the trigger. <> If you go too short your more than likely going to cavitate and loose power. The form of a boats transom varies depending on the manufacturer and model. The height of the boat transom dictates the size of the outboard motor. Boat transom angles play a pivotal role in the flexibility of the boats trimming abilities. Mounting the motor lower on the boat transom can create excessive spray, increase case drag, reduce underwater clearance, and negatively impact faster boats. How to Choose Between a Motor Tote and Transom Saver to Support an Well, raising the outboard motor can be an easy task for you. This transom saver will support the weight of your outboard throughout your road travel, steadily bracing it against the trailer frame to relieve your transom of the weight and impact from consistent bouncing. A reversetransom that sits too high can impact the propellers of the motor and motor bracket. The transom is the boats flat vertical part at the back. If your outboard motor height. your motor will be higher.) Some fishing boats can handle the motor being underwater. When the boat transom is too low, the motor could end up underwater. "brackets". For really big boats, the biggest and baddest six- or eight-cylinder outboards can have extra-extra long shafts up to 30 inches. Although the longer outboard shaft length can lead to lower speed and more drag, the boat can push a heavier load. As summer approaches there will be more boaters taking to the water. So in hopes that this will help out some new boaters this spring, here's a little rundown on outboard shaft sizes and how to figure out which one you actually need. Save my name, email, and website in this browser for the next time I comment. Shaft lengths are available in increments of 5. This will keep the prop in the water when the boat pitches in waves, or hobby-horses. var h = d.getElementsByTagName("head"), Whether you already own a boat or looking for your first watercraft we are here to service your needs. To sum up, there is a simple calculator of the shaft length for outboard motors: Outboard Shaft Length = Transom Height +/- Factors. Attention: Remember to measure the outboard shaft length straight up and down instead of measuring along the transom. There are 2 steps to help get a relatively accurate figure. var h = d.getElementsByTagName("head"), The center is the point where your outboard motor is (ideally) located. What matters is the actual measurement in the specifications, not the name. It was a 23-foot Crestliner Grand Cayman pontoon boat. A1: Broadly speaking, the outboard motor shaft length for pontoon boat, bass boat, or other larger boats should be long shaft. Wherever the outboard clamping bracket is, use this as the basis for measurement. Most transom savers can support up to a 150HP motor, which is sufficient for most regular boats. If you have a small boat with a 15 to 17 inch aft transom, youll most likely need a short shaft outboard. enableMoreInfoLink: true, Setting Height of Outboard Motor - YouTube The height of the transom is estimated by using the center line to measure from the bottom of the hull to the top of the transom. s.setAttribute("src", script); parallel with the straight edge. A yardstick will help you determine if your outboard engine is at the right height. Boost Speed with Outboard Engine Height Adjustments The prop will be in cleaner, harder water as it advances farther aft, making it more efficient. These cookies track visitors across websites and collect information to provide customized ads. This measurement is primarily designed for single motor propulsion. Rebuilt - What You Need to Know, Lower Unit and Sterndrive Break-In Instructions. These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc. Ill also explain the difference between short and long shafts and how they vary by type of boat. To do so, measure from the stern (back) of the boat to the midpoint of the hull on both sides. This is probably the worst case scenario out of the two. These cookies ensure basic functionalities and security features of the website, anonymously. out the confusion. One of the factors in determining the height of the outboard is the placement of the exhaust port on the lower unit of the outboard engine. For example, you can have the Mercury outboard shaft length by model code. This is measured by the propeller shaft being parallel to the vessels bottom. Again, make sure that you are measuring to the flat part of the brackets; You will also risk hitting bottom or submerge objects more frequently such as rocks or logs. Your at your local outboard dealer shopping for a new motor and the salesman hits you with the question, "short or long shaft?". With this in mind, how can I determine if my outboard has a short or long shaft? Required fields are marked *. Smaller boats may use adjustable jack plates that can be changed to fit any outboard. h[0].appendChild(s); (updated Figuring out how to measure motor height on a The transom in a boat today is a place to hang your outboard motor. https:/. Having the cavitation plate a bit lower than the transom is preferable to having it too high. Is my outboard long or short shaft? There is a simple test to see if your outboard motor is set at the best height. Then adjust the motor in a higher hole with a flat head screwdriver. Extra-long shafts are 25-inches long. Raising an outboard higher on the transom can reduce drag and raise top speed. The outboard comes with mounting holes and brackets. The average transom angle is around 14 degrees. So if you are measuring the outboard shaft length for smaller boats, inflatables, dinghies, sailboat or other low-speed work boats, the cavitation plate is often about 2 below the bottom. Step 2: After you get the transom height, add the radius of the propeller (check the user manual, and then technical drawing for the number) to calculate the minimum shaft length needed to make it work.