how to measure transom height for outboard motor

by on April 8, 2023

Boats with more engine power and weight require longer shaft outboards for better balance. Here is a picture that shows you exactly where the outboard motor shaft length stands: Usually the shaft length for outboard motors falls into the following 4 sizes: In practice, you may find the outboard motor shaft length varies among different brands and manufacturers like the Honda,Suzuki, Yamaha, Torqeedo, etc. Whether you already own a boat or looking for your first watercraft we are here to service your needs. Repowering your boat is one of the most expensive upgrades you can make. Doing this can have adverse effects. Mounting the motor lower on the boat transom can create excessive spray, increase case drag, reduce underwater clearance, and negatively impact faster boats. It is extremely important that the boater understands the significance of the transoms height. Read the measurement on the transoms bottom. Its where the outboard motor is attached, and its also where some boat owners put the boats name. The cookie is used to store the user consent for the cookies in the category "Other. You can use a longer shaft than recommended and your boat will work fine. To do so, measure from the stern (back) of the boat to the midpoint of the hull on both sides. up to the bottom of the motor brackets, (as in #1). In the case of a larger offshore boat, it may be to the top of a cutout on the . If your outboard motor height. The distance between the ends of a transom is measured in inches. A reverse transom that sits too high can impact the propellers of the motor and motor bracket. Now that you have a better understanding of boat transom heights its time to take out the ruler and get the perfect measurements. You also have the option to opt-out of these cookies. 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. Ill also explain the difference between short and long shafts and how they vary by type of boat. This alone can outweigh the negatives when deciding to adjust the mount upwards. Engine Oil Type Genuine or Recommended 2str Engine Oil. What are Apple Podcasts Subscriptions and Channels? Another important measurement is the transom angle. A: The short answer is Yes. 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. The boater must also consider if the boat transomsupport is designed to bear the weight of a higher mount. As summer approaches there will be more boaters taking to the water. However, there may be times when a boater strays away from these recommendations. If you have already measured you transom tip to bottom to be 20", then if you place aux sdieways to central engine your available transom height will be probably 1"-1.5" " higher and work perfecty. This distance is very important to the performance of you boat. Tilt your motor until the bullet of the gearcase is This cookie is set by GDPR Cookie Consent plugin. Generally, the anti-ventilation plate on most engines is aligned with the bottom of the vessel. Small motors built for sailboats might come in a unique configuration with an extremely long shaft since these are mounted higher off the water. Take your time and understand your boat and your entire transom. Simply start with the engine in idle, followed by, If you decide to make some custom adjustments we have the. What Kind of Fuel Does Your Marine Engine Need? Theyre also useful if the back of your boat has a non-standard measurement. 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. A2: Instead of changing to the short outboard shaft, you can try the Jack Plate first. Raising the motor increases the speed of the boat while decreasing the effort needed to turn the boat. Mounting kicker motor - General Discussion Forum | In-Depth Outdoors The transom is the "back wall" of your boat, the most rearward part of your hull. Save my name, email, and website in this browser for the next time I comment. See diagram below. I believe 20 to 21 inches is the optimum length for a lengthy shaft. The rearmost structural member of your boat, it not only distributes the stress of the hull generated by the bow's impact as it cleaves the water, it's the place you hang your outboard motor. It does not store any personal data. Beginning boaters should be aware of the boats measurements. This, however, is not recommended for the beginning boater. The boat transom height is measured from the lowest point on the keel along the center line to the spot where the outboard motor's mounting holes bracket rests. Smaller boats may use adjustable jack plates that can be changed to fit any outboard. What is the Virtual Sundance Film Festival? The transom in a boat today is a place to hang your outboard motor. loadScript(ptScript); of the motor off the transom var addyd53b59933f6c3f2e8b59f1b4a6d41fa5 = 'info' + '@'; The same is true for the newest, high-powered offshore fishing boats, where triple or quadruple motor setups are becoming more and more common. There are instances where a lower mount may be okay. As a result, the issue is whether my boat need a short shaft or long shaft motor. If you decide to make adjustments, please consult a marine engine dealer about the boat design. displayPrimeOffers: true, 5/rC,aQhsK@Q. (We wont go into name-calling here, but the actual term for the cavitation plate is an anti-ventilation plate.) Owners of bass boats, RIBs, or offshore fishing boats need to get this right. Increased RPM and additional horsepower feed the need for speed. Like Westshore Marine & Leisure on Facebook! Triton. Recommended Engine Oil 2-Stroke Outboard Motor Oil. }) } }); })(document); Or measure from the main engine prop up to the water line? However, the shaft length for smaller boats could be long or short depending on its style, speed requirement, etc. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. My family and I used it to fish, ski (yes, you can ski behind a pontoon boat), and cruise the lakes near our home. relation to pad For example, you can have the Mercury outboard shaft length by model code. How do you measure a transom on an outboard motor? Yes, if there is adequate space while the engine is tilted in the up position, a larger shaft length than what is specified may be used. Safely but briskly accelerate. 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. Analytical cookies are used to understand how visitors interact with the website. You reply, "Im not sure, I think its a long". The motor is what powers the boat so the two go hand-in-hand. However, the motor should not be raised more than 5 inches above the standard position. PayTomorrow.mpeInit({ The mounting height of an outboard motor can impact the speed and handling characteristics of the boat. What is Transom Height? Boat Transom Heights The Beginners Guide, Buying a boat can be an exciting purchase. An outboard motor can drive just about any sort of boat with proper mounting. var BCData = {"csrf_token":"d7ecb6b56891bb66aee12dbc01a80162b3ed582c1acbe30f16fc9f1b2abc362f"}; 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. :$I>M W$h"%U_yzIb?]NHg_G|r@nX eTf."SQ Because of the increased friction, cavitation reduces efficiency. A reversetransom that sits too high can impact the propellers of the motor and motor bracket. If it measures 15" or with in a inch of that you will need a short shaft outboard. This also means it can affect the safety of the boat. The pressure behind your hand dropped as you slid your hand back and forth through the water. Each one has a totally different effect on the boats performance. You may wonder how deep your prop should be in the water. At least if its too long you can raise the motor or "build up" your transom. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. Save my name, email, and website in this browser for the next time I comment. Plus, a low transom cut is an invitation for the water to flood the boat. Remember, if you use a longer outboard shaft than you need you will be increasing your draft. 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. Yamaha Outboard Motors: How To Measure Leg Length Will Charpentier is a writer who specializes in boating and maritime subjects. If you decide to make some custom adjustments we have theexperience and know-howto make it happen. function loadScript(script) { 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. This illustration depicts four different outboard mounting height options (courtesy Mercury Marine). Smaller 12-14 foot boats can require either a short or long shaft outboard depending on the style of the boat and the brand. Proper Mounting Height for an Outboard - Gone Outdoors It is extremely important that the boater understands the significance of the transom's height. 1855 Alpine Avenue NWGrand Rapids, MI 49504This email address is being protected from spambots. This is measured by the propeller shaft being parallel to the vessels bottom. Later in the article is an image that shows you exactly where to measure. The height of the boat transom dictates the size of the outboard motor. If your boats transom height is 15-16, a short shaft engine is required, and if it is 20-21, a long shaft engine is required. Propshaft in The outboard shaft length is the vertical distance between the top of the mounting clamp bracket and the bottom of the cavitation plate (aka the ventilation plate). And the rule of thumb is that you should keep the cavitation plate level with the bottom or keel of the boat. Add the two measurements and you get 6 1/2". Always weigh the risks of making adjustments. This will ensure the best performance. Place the point of a yardstick at the middle of the top of the boat transom. Shaft lengths are available in increments of 5. This is a measurement that has been used for BassCats, I'm If you have a small boat with a 15 to 17 inch aft transom, youll most likely need a short shaft outboard. Outboards designed for saltwater applications usually have longer shafts. What the relationship to the pontoons is, I couldn't say. You also might not be able to lift the outboard out of the water entirely for storage. enableMoreInfoLink: true, This could also effect your travelling capabilities on the boat trailer. bassboat can be a bit confusing at times; hopefully this will help sort If your boat is newer and the manufacturer is still in business, you might also want to try to give them a call. According to MarinePartsMan.com, the outboard can be raised 1 inch above the standard height for every 10 miles per hour of speed the boat can attain. There are also specialty motor shaft lengths. The height of the boat transom dictates the size of the outboard motor. s.setAttribute("href", "https://cdn.paytomorrow.com/css/pt-mpe.min.css"); <> 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. Extra-extra long shafts are 30-inches long. 2 0 obj So how to measure outboard shaft length? We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. Not to measure boat speed, but to gauge the mounting height of the outboard motor on the boat transom. Whether you already own a boat or looking for your first watercraft we are here to service your needs. How to Raise Outboard Motor on Transom? - Raising the Outboard Motor You'll need a short shaft outboard if it's 15 or less than an inch shorter. Although the longer outboard shaft length can lead to lower speed and more drag, the boat can push a heavier load. This would not be a good thing. former editor at Boating Magazine and contributor to many national publications As a dealer I run into this situation from time to time, which is fine but getting the right length outboard for your boat is crucial. Before we start measuring the outboard shaft length, lets get it clear about whats referring to when we talk about the outboard shaft length. The clamp bracket is designed so that the engine's mounting height on the transom can be adjusted higher than standard. Place the clubs bottom on the ground as though it were going to be used to strike a golf ball. All you need to do is measure how much to rise. Mounting the motor lower on the boat transomcan createexcessive spray, increase case drag, reduce underwater clearance, and negatively impact faster boats. It is where the outboard is mounted, and some boat owners place the name of the boat. When it gets to the short side (14), When the inner corner of the square comes into touch with the transom, measure the distance between the inside corner of the square and the boat bottom (see drawing below). Its still smart to measure it yourself though, just in case, the design changed over the years. 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. Once you know what will fit on your hull, you can fine-tune your choice based on the performance youre looking for and how you use the boat. (616) 364-0666, On all contiguous US part orders over $100. The correct shaft length for your boat depends on a few factors. I would also recommend finding your maximum horsepower rating which is located on the yellow coast guard tag towards the back of your boat. When you measure the width of the stern, mark the center with a grease pencil. With a motor tote, the outboard and boat move as one, independently of the trailer, so there are no concerns about the boat shifting on the trailer, he says. Gear Oil Quantity 195ml(6.6 Fl.oz.) However, youll notice a little increase in drag and a decrease in top-end performance. When trimming your motor, they provide you a greater bow response. It also cuts into speed and fuel efficiency. The cookie is used to store the user consent for the cookies in the category "Performance". trimming the motor out by one-half to full trim. Generally, the anti-ventilation plate on most engines is aligned with the bottom of the vessel. Raising an outboard higher on the transom can reduce drag and raise top speed. This measurement would be the inches of You However, you will need an understanding of how the degrees will alter the boats usability. Extra-long shafts are 25-inches long. How To Mount An Outboard Motor Properly - Start to Finish! Its important to note that manufacturers call their models different things. would be more accurate.) No one wants to have issues with a new transom or boat repairs. Rebuilt - What You Need to Know, Lower Unit and Sterndrive Break-In Instructions. The transom is the flat vertical section at the rear of the boat. If the height of the boat transom is off it can cause major issues. A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. However, you will need an understanding of how the degrees will alter the boats usability. Engine height with stepped hull at transom - before I screw things up Your email address will not be published. There If you have an outboard motor, the distance from one end to another will be found on the side or on a label near its bottom. Measure from the top of the transom to the bottom of the hull. Raising the motor increases the speed of the boat while decreasing the effort needed to turn the boat. You dont have to be a mathematician to determine the correct boat transom angle. Here we will guide you in how to get the right boat transom height. https:/. Lastly, knowing the year of your motor and what style of controls you have (side mount, concealed side mount, or binnacle) is also a plus because it will tell the dealer if your current controls are compatible with the motor you are purchasing. straight edge on the top of the transom to "extend" it out In the case of a dinghy or johnboat, this point may be the top of the transom. If it measures between 17 and 22, you'll want to go with a long shaft motor. How to Measure a Boat Transom - Gone Outdoors Whether your on a pontoon boat, fishing boat, or speedboat boating is always one of the best times you can have. Boat transom angles play a pivotal role in the flexibility of the boats trimming abilities. Long shafts are 20-inches long. It doesnt matter if you have a fiberglass boat, bay boat, big or small boat. Sailboats use these sometimes, as well as some boaters who want to install a much smaller auxiliary motor to use in case of primary engine failure. For most boaters this is a no brainer, but for the novice or inexperienced boater it may be a tougher question. Industry standards dictate that for short shaft engines the transom height should be 15. gtag('config', 'G-QX0Y76NH40'); Whether your on a pontoon boat, fishing boat, or speedboat boating is always one of the best times you can have. Measure straight down to the lowest point on the hull. Then test the boat and adjust the height, if necessary . To do so, you will want to measure at the exact center of the transom from the very top to the very bottom. addyd53b59933f6c3f2e8b59f1b4a6d41fa5 = addyd53b59933f6c3f2e8b59f1b4a6d41fa5 + 'vanssports' + '.' + 'com'; Problems with getting the ventilation plate too low include slower hole-shot and lower top-end speeds. There is a simple test to see if your outboard motor is set at the best height. Expectedly, when the transom angle is zero, it means it is flat. Re: Dinghy with a long shaft motor? How high exactly do you have to raise the transom?-. The motor length corresponds to the transom height of the boat, measured from the keel to gunwale at the transom. s.setAttribute("src", script); Also, the boat will be more likely to hit bottom or submerge objects such as rocks or logs. displayMicroOffers: false, function gtag(){dataLayer.push(arguments);} What is a Transom Saver And Do I Need One? - Boat Safe Well, raising the outboard motor can be an easy task for you. Basically, there are three main ways to measure motor height (that I'm aware of); probably the most common is: # 1: Height of the motor off the transom This is simply a measurement taken from the top of the transom (top of the aluminum plate on top of the transom), to the bottom of the motor "brackets".

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