This is measured by the propeller shaft being parallel to the vessels bottom. These are vertically aligned so the boater can make adjustments. #1: Height The center is the point where your outboard motor is (ideally) located. Necessary cookies are absolutely essential for the website to function properly. The propellers will also have trouble reaching the water. The propellers will also have trouble reaching the water. However, the shaft length for smaller boats could be long or short depending on its style, speed requirement, etc. Boats with extended transoms, brackets that extend the mounting bracket for the outboard motor behind the back of the boat, can use a higher outboard height. of the "bullet" on your lower unit. Simply start with the engine in idle, followed bytrimming the motor out by one-half to full trim. Its still smart to measure it yourself though, just in case, the design changed over the years. The correct shaft length for your boat depends on a few factors. On the downside, a higher mount can interfere with the boaters steering capabilities. The cavitation plate is the horizontal surface of the lower unit immediately above the propeller. This was the height of my 225 Yamaha on my TR21 Step 3: Add another 10 cm (4'') to the previous calculation for the final ideal shaft length. Boat hulls are designed in three basic types that range from slow displacement and semi-displacement hulls to the fastest planing hulls. The collapsing bubbles are loaded with extremely low-pressure water vapor, which causes damage to a variety of surfaces as they collapse. In lower mounting, the engine is set lower than the recommended standard. 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. As with anything, there are exceptions to the rule. If it measures 15" or with in a inch of that you will need a short shaft outboard. The prop will be in cleaner, harder water as it advances farther aft, making it more efficient. Here we will guide you in how to get the right boat transom height. addyd53b59933f6c3f2e8b59f1b4a6d41fa5 = addyd53b59933f6c3f2e8b59f1b4a6d41fa5 + 'vanssports' + '.' + 'com'; It will ensure that the outboards trim will be effective, and it will save you gas too. var ptScript = "https://cdn.paytomorrow.com/js/pt-mpe.min.js"; |. of the motor off the transom Depending on the manufacturer, size names might change. Picking the right shaft length is mostly a factor of the transom height or the back of the boat. var h = d.getElementsByTagName("head"), The vertical distance between the interior of the clamp and the cavitation plate is the shaft length specified by the outboard manufacturer. How can you figure out what your transom angle is? The how to measure the shaft length of an outboard motor is a question that many people have asked. If it measures between 17 and 22, youll want to go with a long shaft motor. If youre going the other way around and trying to figure out how long the shaft on your outboard is, measuring it is equally easy. gtag('js', new Date()); Trimming in, trimming down, and trimming out are all terms that a beginning boater should learn. This restriction includes most fishing boats and longer sailboats. Always weigh the risks of making adjustments. enableMoreInfoLink: true, 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". If you have a question or need additional information. Generally, short shaft outboards are 15 inches, long shaft outboards are 20 inches, and extra-long outboards are 25 inches. 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. 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. If it measures anywhere from 17" to around 22", then your going to want to go with a long shaft motor. 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. On most newer center consoles and offshoreboat transoms might include a rear door leading to a swim platform as well as a molded setback bracket. So its easier and safer to communicate with the dealer with the exact measurement of outboard shaft length in order to get the right model. Place the rulers end on the ground behind the club and let the club to rest on top of it. Later in the article is an image that shows you exactly where to measure. brackets. Tilt your motor until the bullet of the gearcase is var path = 'hr' + 'ef' + '='; Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. Outboards designed for saltwater applications usually have longer shafts. These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc. ), Al Shields 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. Knowing the width, height and depth of your transom allows you to make several important decisions when selecting or purchasing a new outboard. Step 2 requires the propeller's radius (check the user manual and then the technical drawing). Many single-engine boats mount a smaller auxiliary motor for emergency use. You dont have to be a mathematician to determine the correct boat transom angle. mpeInit(); (616) 364-0666, On all contiguous US part orders over $100. Other boats that need extra long shafts are: Read my other articles on outboard motors. boats.com, 1221 Brickell Avenue, 23rd Floor, Miami, FL 33131, USA. How high exactly do you have to raise the transom?-. These are vertically aligned so the boater can make adjustments. Smaller boats may use adjustable jack plates that can be changed to fit any outboard. 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. ensure that your measurement is accurate. resting on the transom if you had the motor all the way down on the boat With a jack plate, you can mount it exactly where you want it. You may wonder how deep your prop should be in the water. The transom is the flat vertical section at the rear of the boat. Check out the full chart of the Mercury outboard model code and its features. want to measure from the transom to the flat part of this bracket, <>/ExtGState<>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 595.2 841.8] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> There are also specialty motor shaft lengths. If you said something smaller than that, thats where it can get tricky. A reversetransom that sits too high can impact the propellers of the motor and motor bracket. <>/Metadata 127 0 R/ViewerPreferences 128 0 R>> a Detwiler manual jackplate. Boat transomangles play a pivotal role in the flexibility of the boats trimming abilities. So how to determine the outboard shaft length? No one wants to have issues with a new transom or boat repairs. Using your existing control box and gauges will save you quite a bit of money in the end. 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. 2 0 obj Now that you have a better understanding of boat transom heights its time to take out the ruler and get the perfect measurements. Spark Plug 25.0nm(18.4 Ft-lb) (2.55 Kgf-m) Basically, there are three main ways to measure motor 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. var xmlHttp = new XMLHttpRequest(); var interval = setInterval(function () { Determining Your Boat Transom Angle The transom angle - commonly measured in degrees - is the transom's vertical inclination. The average transom angle is around 14 degrees. Pretty easy to figure out but like I said its crucial to pairing a motor with a boat. With it comes a lot of responsibility and new things to learn including boat maintenance and boat basics. h[0].appendChild(s); disregard the downward pointing "hooks" at the front of the Look at the part of your motor that would be What matters is the actual measurement in the specifications, not the name. Boat Transom Heights The Beginners Guide, Buying a boat can be an exciting purchase. Your goal is to measure how the outboard will sit, so start from the clamping plate and follow the centerline of the hull. I live for the weekends when I can go out on the water and escape the stress of life on land. Some may call it a standard length while others may call it a short or a long shaft. If it measures 15" or with in a inch of that you will need a short shaft outboard. The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional". But opting out of some of these cookies may affect your browsing experience. A1: Broadly speaking, the outboard motor shaft length for pontoon boat, bass boat, or other larger boats should be long shaft. It doesnt matter if you have a fiberglass boat, bay boat, big or small boat. This measurement is primarily designed for single motor propulsion. hulls, such as Allisons, Bullets, Strokers, etc., this measurement could This is the dimension you'll need when selecting a width for your outboard motor's mounting bracket. Should I take the raft onto the water and measure the exact distance from the top of the transom to the water line? What types of boat need an extra long shaft? The same is true for the newest, high-powered offshore fishing boats, where triple or quadruple motor setups are becoming more and more common. In addition, motor totes will not harm the finish of the lower unit. Always weigh the risks of making adjustments. s.setAttribute("rel", "stylesheet"); A: The short answer is Yes. var h = d.getElementsByTagName("head"), Here we look at the effects of standard, lower and higher mounting. The amount of degrees the transom leans back from vertical is known as the transom angle. actually have the propshaft above the pad.). See diagram below. It is very versatile as it generally . parallel with the straight edge. A reverse transom that sits too high can impact the propellers of the motor and motor bracket. This measurement was approximately 4". motor brackets For example, you can have the Mercury outboard shaft length by model code. If you have a jackplate, you may have to get a bit creative in your %PDF-1.7 the aluminum plate on top of the transom), to the bottom of the motor up to the bottom of the motor brackets, (as in #1). (Putting a The dealer just hit you with the long or short shaft question and you have no clue as to what you need or even what he's talking about. https:/. C Cheaptoon Cadet Joined Aug 4, 2010 Messages 28 Aug 24, 2010 #4 Re: Motor height on pontoon? Because of the increased friction, cavitation reduces efficiency. The transom is the boats flat vertical part at the back. Save my name, email, and website in this browser for the next time I comment. Industry standards dictate that for short shaft engines the transom height should be 15. Engine Oil Type Genuine or Recommended 2str Engine Oil. For slower boats, its less critical to. (1) Multiply the overall length of your boat (in feet) by it's widest beam at the stern (excluding any Fins and or Shear) (2) Locate that value on the left hand vertical column of the chart below. Plus, a low transom cut is an invitation for the water to flood the boat. It also cuts into speed and fuel efficiency. Doing this can have adverse effects. Boats with more engine power and weight require longer shaft outboards for better balance. An outboard motor can drive just about any sort of boat with proper mounting. You also might not be able to lift the outboard out of the water entirely for storage. Which Navigation Lights Does Your Boat Need? 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. What are Apple Podcasts Subscriptions and Channels? Adjusting the mounting height of an outboard on the boat transom can affect performance and every boat can be different, so actual on-water testing is best. Wherever the outboard clamping bracket is, use this as the basis for measurement. You need JavaScript enabled to view it. But, how do you measure it? Knowing how this can affect the overall operation of the boat is a factor to be considered. maxMicroAmount: 0.0, Owners of bass boats, RIBs, or offshore fishing boats need to get this right. }) } }); })(document); However, with the outboard shaft length too short, meaning the prop is too close to the surface, the engine is likely to ventilate and therefore slip on acceleration or lose power. would be more accurate.) This is also known as the shaft length. To make the yard stick long enough to measure the length of all the clubs, tape the ruler to the top. They operate as a planing surface, allowing your boat to climb to the top more quickly. logoColor: "original", The transom in a boat today is a place to hang your outboard motor. High powered boats usually only come in long and extra-long variants. In extremes, the engine can have overheating problems if the boat is raised to a point where the water inlets for the cooling system are out of the water. Recommended Engine Oil 2-Stroke Outboard Motor Oil. Then, you can pick the right engine. When trimming your motor, they provide you a greater bow response. Then finally test your outboard, if the mount is perfect. The outboard comes with mounting holes and brackets. priceSelector: ".price--withoutTax, span.price.price--withTax", His works have appeared in regional newspapers in North Dakota and in "North Dakota Horizons" and "Cowboys and Indians" magazines. Doing so, will put the propeller right below the boat. Its where the outboard motor is attached, and its also where some boat owners put the boats name. To do so, measure from the stern (back) of the boat to the midpoint of the hull on both sides. stream A hydrofoil will typically level off the ride by driving the stern up and the bow down, and will stop or considerably minimize porposing on a 16 footer with a mid-sized outboard and no tabs, for example. s.setAttribute("href", "https://cdn.paytomorrow.com/css/pt-mpe.min.css"); If the height of the boat transom is off it can cause major issues. If your boat is newer and the manufacturer is still in business, you might also want to try to give them a call. The mounting height of the outboard engine is the equivalent of the distance between the base of the motor and the top of the propeller. 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. If mounting directly to a boat transom: Measure from the top of the transom down to the bottom of the hull or keel (lowest point). Rebuilt - What You Need to Know, Lower Unit and Sterndrive Break-In Instructions. It does not store any personal data. straight edge on the top of the transom to "extend" it out Measuring the shaft length can be done in various ways, but the most common way is by using a tape measure. Measure the area of the transom directly where the engine will be mounted. Each one has a totally different effect on the boats performance. I mean it is better to be safe than sorry, am I right? If your boat planes, pay extra attention to getting the shaft length as close to perfect as possible. 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. What Kind of Fuel Does Your Marine Engine Need? So how to measure outboard shaft length? If your outboard motor height. Or measure from the main engine prop up to the water line? Will Charpentier is a writer who specializes in boating and maritime subjects. mpeSelector: ".pt-mpe", Other factors to consider when determining the mounting height of an outboard are related to performance. When you measure the width of the stern, mark the center with a grease pencil. Simply start with the engine in idle, followed by trimming the motor out by one-half to full trim. Amazon has plate extensions to allow adjustments without buying a new motor: T-H Marine Jack Plate Extension. It also decreases the boats lift and increases the time it takes for the boat to reach plane. On the downside, a higher mount can interfere with the boaters steering capabilities. bracket. Some fishing boats can handle the motor being underwater. The boat transom can be flat with zero degree angles. manufacturer will recommend the outboard height according to the bracket shape and length. Move the bracket as close to the center of the transom as possible while still maintaining clearance to allow the main outboard or rudder to reach its full range of motion without contacting the kicker motor. How to Buy a Boat: Tips for a First Time Buyer, Top 10 New Fishing Boats for Under $20,000, What Type is Right for You? 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. There is a simple test to see if your outboard motor is set at the best height. s = d.createElement("script"); Each one has a totally different effect on the boats performance. What's the best height for my boat motor? This could also affect your travelling capabilities on the boat trailer. As a result, the issue is whether my boat need a short shaft or long shaft motor. Follow Westshore Marine & Leisure on Wordpress! 1855 Alpine Avenue NWGrand Rapids, MI 49504This email address is being protected from spambots. If so, send me an Re: Dinghy with a long shaft motor? Lubrication System Engine Oil Mixed Gasoline. However, youll notice a little increase in drag and a decrease in top-end performance. The boater must also consider if the boat transomsupport is designed to bear the weight of a higher mount. The motor is what powers the boat so the two go hand-in-hand. With such an important, long-term, and expensive upgrade, its never a bad idea to double-check. the propshaft below or above the pad. It is extremely important that the boater understands the significance of the transom's height. Mounting the motor lower on the boat transom can create excessive spray, increase case drag, reduce underwater clearance, and negatively impact faster boats. displayMicroOffers: false, It is where the outboard is mounted, and some boat owners place the name of the boat. This alone can outweigh the negatives when deciding to adjust the mount upwards. former editor at Boating Magazine and contributor to many national publications The average transom angle is around 14 degrees. If you are running a slower boat, the exact location of the ventilation plate is less important. Hold the tape on the top, center of the taffrail and measure straight down to the point, usually a sharp angle, where the transom joins the bottom of the boat. #2. Take a long straight edge, (long carpenter's level or long Thats a fairly simple list of symptoms, but if your motor is too low, youll probably notice at least one of them. Increased RPM and additional horsepower feed the need for speed. Place the bracket on the transom to the left of the main outboard or rudder. Set the end of the tape on the outside edge of the taffrail at the center and measure inward to the inside edge of the taffrail. He is also a certified marine technician and the author of a popular text on writing local history. Boaters who consider going with a higher mount can see increased speeds. Typical motor lengths include the following. Anything bigger than that your obviously going to need an extra long shaft. Cavitation plates are used on the bottom components of boats to help them operate better. Safely but briskly accelerate. If you have a small boat with a 15 to 17 inch aft transom, youll most likely need a short shaft outboard. Next, measure from your centerline to where the outboard will be mounted on each side. Workboats, sailboats, and displacement-hulled boats fall into this category. The transom is the "back wall" of your boat, the most rearward part of your hull. Step 4. Check out the Westshore Marine & Leisure Youtube page! Engine Oil Mixing Ratio Fuel 50: Engine Oil 1. Raising the motor increases the speed of the boat while decreasing the effort needed to turn the boat. Measure from the top of the transom to the bottom of the hull. This illustration depicts four different outboard mounting height options (courtesy Mercury Marine). 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. The form of a boats transom varies depending on the manufacturer and model. If you are running a twin-engine setup, then measure the same distance from each clamping plate to the bottom of the hull. As summer approaches there will be more boaters taking to the water. Whether your on a pontoon boat, fishing boat, or speedboat boating is always one of the best times you can have. Knowing how this can affect the overall operation of the boat is a factor to be considered. The distance between the ends of a transom is measured in inches. loadScript(ptScript); Displacement hulled vessels like sailboats and workboats can benefit from a little more space between the hull and cavitation plate, but not much. The clamp bracket is designed so that the engine's mounting height on the transom can be adjusted higher than standard. Measure from the top of the transom to the bottom of the hull. 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. minAmount: 300.0, <> Extra-long shafts are 25-inches long. However, there may be times when a boater strays away from these recommendations. I would also recommend finding your maximum horsepower rating which is located on the yellow coast guard tag towards the back of your boat. If the propeller fails to ventilate, the motor is mounted to low. Eq*^?6R83e+j}UY.(M7k]~4g)g ~wmS{ O7t/o(W|X? Having the cavitation plate a bit lower than the transom is preferable to having it too high. Now that you have a better understanding of boat transom heights its time to take out the ruler and get the perfect measurements. (updated This also means it can affect the safety of the boat. var prefix = 'ma' + 'il' + 'to'; boats.com is part of the Boats Group Network. To achieve this, the motor itself has to be attached at the correct height. The cookie is used to store the user consent for the cookies in the category "Analytics". At least if its too long you can raise the motor or "build up" your transom. 1 0 obj e-mail If you have a question or need additional information,contact ustoday. He is a Raising the motor increases the speed of the boat while decreasing the effort needed to turn the boat. 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. The point where these measurements intersect is your centerline. You can order an outboard in lengths ranging from 15 inches to 30 inches, depending on its power output and possible uses. By clicking Accept, you consent to the use of ALL the cookies. Boaters who consider going with a higher mount can see increased speeds. since 1986. Small motors built for sailboats might come in a unique configuration with an extremely long shaft since these are mounted higher off the water. and I'll explain it better, (or point you to someone that can help. The pressure behind your hand dropped as you slid your hand back and forth through the water. Many boat transoms are modified to use a different length of outboard by using a bracket. This website uses cookies to improve your experience while you navigate through the website. Chances are the boat was designed with a specific size of outboard in mind. The brackets can add 1 inch to the overall mounting height of the outboard. 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. Before we get started lets see what a boat transom is and what it does. This cookie is set by GDPR Cookie Consent plugin. For boats equipped with a bracket, calculate the same measurement but based on the bracket and not the transom. Use the mounting bracket on the motor to know where it will sit on the boat. Take the center measurement from the top to the bottom of the hull. (We wont go into name-calling here, but the actual term for the cavitation plate is an anti-ventilation plate.) Why wont Touch ID be under the screen in the iPhone 15 and iPhone 16? h[0].appendChild(s); So if you are measuring the outboard shaft length for the powerboat, planing boat, or any boat for which the speed is the priority, take the outboard shaft length 1 to 1.5 (depending on your boat types) shorter than standard would be better. Copyright 1999-2023 Boats Group. Expectedly, when the transom angle is zero, it means it is flat. Check out the Westshore Marine & Leisure google plus page! 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. Follow Westshore Marine & Leisure on Twitter! A: The answer varies by boat, but here are some rules of thumb for matching a short shaft outboard to your boat. Functional cookies help to perform certain functionalities like sharing the content of the website on social media platforms, collect feedbacks, and other third-party features. var addyd53b59933f6c3f2e8b59f1b4a6d41fa5 = 'info' + '@'; If you are looking to repower, they may be able to offer some sage advice. Place the point of a yardstick at the middle of the top of the boat transom. Required fields are marked *. will be to the flat part; if you measure to the bottom of the brackets