how to measure transom height for outboard motor how to measure transom height for outboard motor

s = d.createElement("link"); Take your time and understand your boat and your entire transom. The prop will be in cleaner, harder water as it advances farther aft, making it more efficient. Among them will be first-timers or those who have recently purchased their boats. Most of the time, adding a hydrofoil to an outboard improves performance. Doing so, will put the propeller right below the boat. A: The short answer is Yes. s.setAttribute("type", "text/javascript"); The current measurement is the ventilation plate is about 1 1/2" above the true keel line which is about 24" in front of the motor edge. However, there may be times when a boater strays away from these recommendations. Tightening Torque for Engine. What Kind of Fuel Does Your Marine Engine Need? It is where the outboard is mounted, and some boat owners place the name of the boat. Generally, the anti-ventilation plate on most engines is aligned with the bottom of the vessel. Then, you can pick the right engine. 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. Check out some hot FAQs to help you get the proper outboard shaft lengths. jackplate to a point level with the top of the transom. These are vertically aligned so the boater can make adjustments. logoColor: "original", Its important to note that manufacturers call their models different things. xmlHttp.send('{"store_id":"369079","timezone_offset":"-5","timestamp":"2023-03-04T05:39:31.71020200Z","visit_id":"e2642be3-34e5-4a48-b89d-639d139834e0","channel_id":1}'); 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. You may wonder how deep your prop should be in the water. You can find your Mercury outboard model code on an ID plate or sticker. The brackets can add 1 inch to the overall mounting height of the outboard. } A: The answer varies by boat, but here are some rules of thumb for matching a short shaft outboard to your boat. If you said you have a pontoon or a larger style boat such as a bass boat or speed boat, I would be pretty confident in saying it needs a long shaft. storeDisplayName: "Marine Parts Warehouse", Charles Plueddeman is Boats.com's outboard, trailer, and PWC expert. function mpeInit() { %PDF-1.7 Beginning boaters should be aware of the boats measurements. Extra-long shafts are 25-inches long. Whether you already own a boat or looking for your first watercraft we are here to service your needs. This was the height of my 225 Yamaha on my TR21 Bass boats, ski boats, or center cockpit vessels will want to double-check their measurements to get it just right. Generally, the anti-ventilation plate on most engines is aligned with the bottom of the vessel. In lower mounting, the engine is set lower than the recommended standard. "brackets". Is my outboard long or short shaft? While this is the case there is certain saltwater motors that are extra extra long at 30. Raising an outboard higher on the transom can reduce drag and raise top speed. Lubrication System Engine Oil Mixed Gasoline. Its where the outboard motor is attached, and its also where some boat owners put the boats name. Sluggish speeds, poor handling, heavy spray, porpoising, or even water pushing up into the cowling are all signs that an outboard is set too low. 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. Allowing the propeller to pull water from underneath and push it out behind the boat. function loadScript(script) { It will ensure that the outboards trim will be effective, and it will save you gas too. The transom is the rear wall of the boat where the outboard engine is mounted in the middle. When you measure the width of the stern, mark the center with a grease pencil. This restriction includes most fishing boats and longer sailboats. Step 2 requires the propeller's radius (check the user manual and then the technical drawing). See diagram below. The cookie is used to store the user consent for the cookies in the category "Other. The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional". Measuring the shaft length can be done in various ways, but the most common way is by using a tape measure. Two years ago, I bought a Boston Whaler to fish off the coast. Safely but briskly accelerate. (We wont go into name-calling here, but the actual term for the cavitation plate is an anti-ventilation plate.) So how to determine the outboard shaft length? Some fishing boats can handle the motor being underwater. It is where the outboard is mounted, and some boat owners place the name of the boat. #3. (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. If it measures anywhere from 17" to around 22", then your going to want to go with a long shaft motor. To achieve this, the motor itself has to be attached at the correct height. In step 3, add another 10 cm (4") to the previous calculation in order to develop the ideal shaft length. No one wants to have issues with a new transom or boat repairs. If your boat planes, pay extra attention to getting the shaft length as close to perfect as possible. Other factors to consider when determining the mounting height of an outboard are related to performance. var h = d.getElementsByTagName("head"), 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. Among them will be first-timers or those who have recently purchased their boats. a Detwiler manual jackplate. since 1986. Why wont Touch ID be under the screen in the iPhone 15 and iPhone 16? And the rule of thumb is that you should keep the cavitation plate level with the bottom or keel of the boat. One of the main concerns is causing the engine to overheat if not enough water reaches the engine to keep it cool. So you should just measure the height of the boats transom from the center down to the lowest point of the hull, and compare transom height with the outboard shaft length numbers. maxMicroAmount: 0.0, Thats it. This measurement is primarily designed for single motor propulsion. The height of the boat transom dictates the size of the outboard motor. Any owner seeking the last bit of speed from an outboard-powered boat should grab a yard stick. In the second photo, we've measure down from the top of the Detwiler The first step is to determine the height of your boat's transom. (updated It is extremely important that the boater understands the significance of the transoms height. Using your existing control box and gauges will save you quite a bit of money in the end. The transom angle is the vertical incline of the transom and is measured in degrees. The shaft length for outboard motors has nothing to do with the water line. Although the longer outboard shaft length can lead to lower speed and more drag, the boat can push a heavier load. Its still smart to measure it yourself though, just in case, the design changed over the years. 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. straight edge from the center of the pad, but this time you're measuring 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. MarinePartsMan.com also says that V6 bass-boat engines have a 20-inch shaft. This will ensure the best performance. The engine may be lifted one inch for every eight to ten inches of distance between the transom and the prop, according to a boat riggers rule of thumb. Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. This measurement was approximately 4". Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. You Now that you have a better understanding of boat transom heights its time to take out the ruler and get the perfect measurements. })(); Knowing how this can affect the overall operation of the boat is a factor to be considered. Which Navigation Lights Does Your Boat Need? As a yacht designer and boater, I prefer longer shafts. The cookies is used to store the user consent for the cookies in the category "Necessary". s = d.createElement("script"); I mean it is better to be safe than sorry, am I right? maxAmount: 6500.0, This could also effect your travelling capabilities on the boat trailer. Save my name, email, and website in this browser for the next time I comment. At least if its too long you can raise the motor or "build up" your transom. Boaters who consider going with a higher mount can see increased speeds. var addyd53b59933f6c3f2e8b59f1b4a6d41fa5 = 'info' + '@'; Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. Read the measurement on the transoms bottom. Use the mounting bracket on the motor to know where it will sit on the boat. Outboards designed for saltwater applications usually have longer shafts. There are also specialty motor shaft lengths. Doing this can have adverse effects. Brackets are also handy for boats that do not have flat transoms, like canoe-stern sailboats or fan-tailed motor vessels. Ten years ago I bought my first boat. Engine Oil Mixing Ratio Fuel 50: Engine Oil 1. Place the rulers end on the ground behind the club and let the club to rest on top of it. Check the literature about your model boat online, and you may be surprised to find that the number is published for you. 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. This email address is being protected from spambots. This will keep the prop in the water when the boat pitches in waves, or hobby-horses. This exhaust port should be about 1 inch above the water line when the boat is idling. Tilt your motor until the bullet of the gearcase is var ptScript = "https://cdn.paytomorrow.com/js/pt-mpe.min.js"; Triton. The standard shaft length for most outboard engines less than 125 horsepower is 20 inches. Take the center measurement from the top to the bottom of the hull. This allows the engine to idle without the flow of the exhaust being restricted. xmlHttp.setRequestHeader('Content-Type', 'application/json'); The Effects of Standard, Lower and Higher Mounting. If you are running a slower boat, the exact location of the ventilation plate is less important. primeApr: 12.99, Measure from the top of the straight edge to the center of the front You dont have to be a mathematician to determine the correct boat transom angle. Owners of bass boats, RIBs, or offshore fishing boats need to get this right. To make the yard stick long enough to measure the length of all the clubs, tape the ruler to the top. Measure from there down to the top of the cavitation plate, also known as the anti-ventilation plate. My family and I used it to fish, ski (yes, you can ski behind a pontoon boat), and cruise the lakes near our home. A reverse transom that sits too high can impact the propellers of the motor and motor bracket. For vessels with transom-mounted outboards, you can easily figure out which type of outboard you need to get. However, the motor should not be raised more than 5 inches above the standard position. The boater must also consider if the boat transom support is designed to bear the weight of a higher mount. Boat Transom Heights The Beginners Guide, Buying a boat can be an exciting purchase. Each one has a totally different effect on the boats performance. We also use third-party cookies that help us analyze and understand how you use this website. AztH ^zv_ cT,E1K/rAB54| Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. Other boats that need short shafts are: A: If you have a small boat with a 18 to 21 inch aft transom, youll most likely need a long shaft outboard. 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. The motor length corresponds to the transom height of the boat, measured from the keel to gunwale at the transom. If the propeller fails to ventilate, the motor is mounted to low. trimming the motor out by one-half to full trim. If it measures 15" or with in a inch of that you will need a short shaft outboard. Since the length of the shaft of your outboard is associated with the size boat, smaller engines will generally have shorter shafts. This is the dimension you'll need to know when deciding between a short shaft, long shaft or extra long shaft for your outboard motor. With a jack plate, you can mount it exactly where you want it. Many single-engine boats mount a smaller auxiliary motor for emergency use. You will also risk hitting bottom or submerge objects more frequently such as rocks or logs. You dont have to be a mathematician to determine the correct boat transomangle. A yardstick will help you determine if your outboard engine is at the right height. Most transom savers can support up to a 150HP motor, which is sufficient for most regular boats. The boat transom can be flat with zero degree angles. Measure the area of the transom directly where the engine will be mounted. The point where these measurements intersect is your centerline. If you have a small boat with a 15 to 17 inch aft transom, youll most likely need a short shaft outboard. the aluminum plate on top of the transom), to the bottom of the motor With it comes a lot of responsibility and new things to learn including boat maintenance and boat basics. The performance of these boats depends on quite a lot of factors, but getting the outboard length just right is an essential first step. bassboat can be a bit confusing at times; hopefully this will help sort All rights reserved. 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. This is somewhat similar to #2, in that you are again measuring with a Upstream Securitys Disruptive Telematics Technology, The challenges of scaling a cloud-based security system, OneStreams unified platform streamlines financial data management, OneStreams impact on the financial software market. Simply start with the engine in idle, followed by trimming the motor out by one-half to full trim. e-mail This alone can outweigh the negatives when deciding to adjust the mount upwards. 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. The collapsing bubbles are loaded with extremely low-pressure water vapor, which causes damage to a variety of surfaces as they collapse. You can order an outboard in lengths ranging from 15 inches to 30 inches, depending on its power output and possible uses. boats.com is part of the Boats Group Network. To achieve 35 mph with a 6 hp engine, the total weight is 135 lbs (boat motor fuel passengers). Then finally test your outboard, if the mount is perfect. Mounting the motor lower on the boat transomcan createexcessive spray, increase case drag, reduce underwater clearance, and negatively impact faster boats. straight edge on the top of the transom to "extend" it out Beefier jack plates can be fitted should a boater be looking to mount an outboard with a shorter shaft than their transom demands. Always weigh the risks of making adjustments. s.setAttribute("rel", "stylesheet"); Follow Westshore Marine & Leisure on Wordpress! As summer approaches there will be more boaters taking to the water. The outboard comes with mounting holes and brackets. A reversetransom that sits too high can impact the propellers of the motor and motor bracket. It is unsafe to have the engine block too close to the water on a low transom. 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. In the past, though, it housed the officers and captain of 17th, 18th and 19th century sailing ships. h[0].appendChild(s); Problems with getting the ventilation plate too low include slower hole-shot and lower top-end speeds. mpeInit(); It also includes attaching the right engine. Increased RPM and additional horsepower feed the need for speed. For example, you can have the Mercury outboard shaft length by model code. On the downside, a higher mount can interfere with the boaters steering capabilities. Safely but briskly accelerate. Save my name, email, and website in this browser for the next time I comment. Before we get started lets see what a boat transom is and what it does. | Sitemap, The Marine Parts Warehouse Outboard Museum, OBR Powerhead / Shortblock Warranty Claim Form, Remanufactured vs. A: Any boat that has a 21 to 27 inch aft transom will need an extra long shaft outboard. If you have a jackplate, you may have to get a bit creative in your What are Apple Podcasts Subscriptions and Channels? How the outboard will sit on the back of the boat depends on how the transom is designed. If it measures between 17 and 22, youll want to go with a long shaft motor. brackets. to where the brackets were actually resting on the transom. Here we will guide you in how to get the right boat transom height. 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. This also means it can affect the safety of the boat. All you need to do is measure how much to rise. Your at your local outboard dealer shopping for a new motor and the salesman hits you with the question, "short or long shaft?". The boat transom can be flat with zero degree angles. This is simply a measurement taken from the top of the transom (top of There are 2 steps to help get a relatively accurate figure. var interval = setInterval(function () { The vertical distance between the interior of the clamp and the cavitation plate is the shaft length specified by the outboard manufacturer. resting on the transom if you had the motor all the way down on the boat 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". PayTomorrow.mpeInit({ Whether your on a pontoon boat, fishing boat, or speedboat boating is always one of the best times you can have. Setting Height of Outboard Motor - YouTube 0:00 / 0:46 Setting Height of Outboard Motor nates90 71 subscribers Subscribe 83 Share 63K views 7 years ago #boatservice #outboardmotor. Step 3: Add another 10 cm (4'') to the previous calculation for the final ideal shaft length. enableMoreInfoLink: true, Transom Outboard Engine Position - YouTube 0:00 / 0:56 Transom Outboard Engine Position BOATING SCENE 763 subscribers 609 211K views 5 years ago www.boatingscene.com.au Sometimes when your. How high exactly do you have to raise the transom?-. Learn More About Your Boats Systems By Joining The Born Again Boating Academy! This number will likely be shorter than that for a single-engine installation since you do not necessarily measure to the point of the keel. former editor at Boating Magazine and contributor to many national publications As a result, the issue is whether my boat need a short shaft or long shaft motor. Shaft lengths are available in increments of 5. 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. Having the cavitation plate a bit lower than the transom is preferable to having it too high. center of the propshaft. By clicking Accept, you consent to the use of ALL the cookies. These cookies track visitors across websites and collect information to provide customized ads. Beyond motorboats designed for large outboards, you will see outboards hanging on the sterns of everything from small canoes to large cruising sailboats. There are instances where a lower mount may be okay. However, your boat will have slightly more drag which will reduce your maximum speed. The how to measure the shaft length of an outboard motor is a question that many people have asked. As mentioned above, the operation of the propeller relies on the transom height. Measure straight down to the lowest point on the hull. The mounting height of an outboard motor can impact the speed and handling characteristics of the boat. To do so, you will want to measure at the exact center of the transom from the very top to the very bottom. Boats with more engine power and weight require longer shaft outboards for better balance. The clamp bracket is designed so that the engine's mounting height on the transom can be adjusted higher than standard. This, however, is not recommended for the beginning boater. Commonly, the transom angle ranges from 0-30 degrees, with the average transom angle set at 14 degrees. Next, measure from your centerline to where the outboard will be mounted on each side. This website uses cookies to improve your experience while you navigate through the website. All things considered, sticking with the industry standard is best for the beginner. Look at the part of your motor that would be A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. } Typical motor lengths include the following. Will Charpentier is a writer who specializes in boating and maritime subjects. Displacement hulled vessels like sailboats and workboats can benefit from a little more space between the hull and cavitation plate, but not much. Buying a boat can be an exciting purchase. They keep water out of your prop and increase water pressure in the system. Workboats, sailboats, and displacement-hulled boats fall into this category. And thats usually the case since the electric outboards are designed with larger and more efficient propeller that needs longer shaft. 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. Plus, a low transom cut is an invitation for the water to flood the boat. 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). gtag('js', new Date()); (Putting a 7. If the height of the boat transom is off it can cause major issues. This cookie is set by GDPR Cookie Consent plugin. In addition, motor totes will not harm the finish of the lower unit. Youll need a short shaft outboard if its 15 or less than an inch shorter. Youll also want to pay attention when youre in shallow water because your prop will be lower than normal. var path = 'hr' + 'ef' + '='; Extra-extra long shafts are 30-inches long. This distance is very important to the performance of you boat. If your outboard motor height. However, youll notice a little increase in drag and a decrease in top-end performance.