When the boattransom is too low, the motor could end up underwater. 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. 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. This exhaust port should be about 1 inch above the water line when the boat is idling. publicId: "32bf3437d1346295e03ebcf545f9c839", Ill also explain the difference between short and long shafts and how they vary by type of boat. To break it down a bit more for you: Short shafts are 15-inches long. 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. Take your time and understand your boat and your entire transom. There are instances where a lower mount may be okay. The shaft length for outboard motors has nothing to do with the water line. not sure that it's still used. 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. clearInterval(interval); Generally, the anti-ventilation plate on most engines is aligned with the bottom of the vessel. (Any measurement given as "off the transom" Which Navigation Lights Does Your Boat Need? Usually speaking, the farther the outboard is set off the transom, the higher the propeller should be in the water (or the higher the outboard can be mounted). This, however, is not recommended for the beginning boater. It moves an outboard up and down to optimize performance and enable a boat to venture into shallower water than it might otherwise. Shaft lengths are available in increments of 5. Then, you can pick the right engine. How can you figure out what your transom angle is? Charles Plueddeman is Boats.com's outboard, trailer, and PWC expert. You'll need a short shaft outboard if it's 15 or less than an inch shorter. It varies between different motors and boats. Youll also want to pay attention when youre in shallow water because your prop will be lower than normal. A transom saver, which can change the spacing between the lower unit and the trailer, negates some of the support. (127 mm). Allowing the propeller to pull water from underneath and push it out behind the boat. Here we look at the effects of standard, lower and higher mounting. Boaters who consider going with a higher mount can see increased speeds. Follow Westshore Marine & Leisure on Twitter! In the case of a larger offshore boat, it may be to the top of a cutout on the . You must be still in the blue about that matter. Say the 20 shaft is a long shaft length for gas engines, but it is a short shaft length for electric outboard motors. 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}'); var interval = setInterval(function () { Always weigh the risks of making adjustments. For vee-shaped hulls, the lowest spot of the hull will come to point, while on flat-bottomed boats it will be more or less level. Another important measurement is the transom angle. Having the cavitation plate a bit lower than the transom is preferable to having it too high. This, however, is not recommended for the beginning boater. He is also a certified marine technician and the author of a popular text on writing local history. So how to measure outboard shaft length? These allow the mounting of a standard length outboard behind the transom. The faster your boat, the more critical it is to get the sizing just right. The greater the number, the more the drive may sway (also called tuck under or negative trim). Before we start measuring the outboard shaft length, lets get it clear about whats referring to when we talk about the outboard shaft length. How to Buy a Boat: Tips for a First Time Buyer, Top 10 New Fishing Boats for Under $20,000, What Type is Right for You? manufacturer will recommend the outboard height according to the bracket shape and length. If it measures 15" or with in a inch of that you will need a short shaft outboard. With the long side (22 1/2), place a carpenters square ) in opposition to the keel. endobj ), Al Shields If mounting directly to a boat transom: Measure from the top of the transom down to the bottom of the hull or keel (lowest point). The cookie is used to store the user consent for the cookies in the category "Performance". The form of a boats transom varies depending on the manufacturer and model. The transom is the "back wall" of your boat, the most rearward part of your hull. It is where the outboard is mounted, and some boat owners place the name of the boat. Learn More About Your Boats Systems By Joining The Born Again Boating Academy! However, the shaft length for smaller boats could be long or short depending on its style, speed requirement, etc. Displacement hulled vessels like sailboats and workboats can benefit from a little more space between the hull and cavitation plate, but not much. In lower mounting, the engine is set lower than the recommended standard. The standard installation of an outboard has the top of the transom of the boat at the same level as the bottom of the motor portion of the outboard. What matters is the actual measurement in the specifications, not the name. A hydrofoil will typically level off the ride by driving the stern up and the bow down, and will stop or considerably minimize porposing on a 16 footer with a mid-sized outboard and no tabs, for example. If you have already measured you transom tip to bottom to be 20", then if you place aux sdieways to central engine your available transom height will be probably 1"-1.5" " higher and work perfecty. :$I>M W$h"%U_yzIb?]NHg_G|r@nX eTf."SQ Trimming in, trimming down, and trimming out are all terms that a beginning boater should learn. To do so, you will want to measure at the exact center of the transom from the very top to the very bottom. While this is the case there is certain saltwater motors that are extra extra long at 30 and 35 shaft. 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. disregard the "hooks" at the front of the If it measures anywhere from 17" to around 22", then your going to want to go with a long shaft motor. (3) Move horizontally across the chart until you hit the graph curve. Eq*^?6R83e+j}UY.(M7k]~4g)g ~wmS{ O7t/o(W|X? MPW eBay Store - Thousands of New OEM Old Stock Parts! The boat transom can be flat with zero degree angles. Step 2 requires the propeller's radius (check the user manual and then the technical drawing). will be to the flat part; if you measure to the bottom of the brackets There are also specialty motor shaft lengths. There are instances where a lower mount may be okay. Boats with more engine power and weight require longer shaft outboards for better balance. Although the longer outboard shaft length can lead to lower speed and more drag, the boat can push a heavier load. We also use third-party cookies that help us analyze and understand how you use this website. However, youll notice a little increase in drag and a decrease in top-end performance. If the propeller fails to ventilate, the motor is mounted to low. 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). s.setAttribute("src", script); the aluminum plate on top of the transom), to the bottom of the motor This allows the engine to idle without the flow of the exhaust being restricted. 4 0 obj Its important to note that manufacturers call their models different things. mpeSelector: ".pt-mpe", (616) 364-0666, On all contiguous US part orders over $100. Check out the full chart of the Mercury outboard model code and its features. The prop will be in cleaner, harder water as it advances farther aft, making it more efficient. Thats a fairly simple list of symptoms, but if your motor is too low, youll probably notice at least one of them. There are a series of four to six holes at the top of the bracket, and the lower bolts actually fit into slots. Like Westshore Marine & Leisure on Facebook! Trimming in, trimming down, and trimming out are all terms that a beginning boater should learn. parallel with the straight edge. 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 you have a fast boat, getting the outboards cavitation plate at the same level of the hull will ensure quick hole shot and fast top-end speeds. | Sitemap, The Marine Parts Warehouse Outboard Museum, OBR Powerhead / Shortblock Warranty Claim Form, Remanufactured vs. PayTomorrow.mpeInit({ Amazon has plate extensions to allow adjustments without buying a new motor: T-H Marine Jack Plate Extension. See When St. Peters Basketball Games Are Today! Typical motor lengths include the following. Since the ventilation plate & foil are burried under water it is obviously too low. 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. As a yacht designer and boater, I prefer longer shafts. Most transom savers can support up to a 150HP motor, which is sufficient for most regular boats. Simply start with the engine in idle, followed by, If you decide to make some custom adjustments we have the. A: Any boat that has a 21 to 27 inch aft transom will need an extra long shaft outboard. Other boats that need extra long shafts are: Read my other articles on outboard motors. In the photo above, we've measured from the motor bracket to the top of But in many cases, its a little more complicated than that alone. It also includes attaching the right engine. xmlHttp.open('POST', 'https://bes.gcp.data.bigcommerce.com/nobot'); They keep water out of your prop and increase water pressure in the system. If your boat planes, pay extra attention to getting the shaft length as close to perfect as possible. MarinePartsMan.com also says that V6 bass-boat engines have a 20-inch shaft. Boat transom angles play a pivotal role in the flexibility of the boats trimming abilities. displayPrimeOffers: true, 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. Anything bigger than that your obviously going to need an extra long shaft. The height of the boat transom dictates the size of the outboard motor. This is somewhat similar to #2, in that you are again measuring with a if (PayTomorrow) { What are Apple Podcasts Subscriptions and Channels? Tilt your motor until the bullet of the gearcase is addyd53b59933f6c3f2e8b59f1b4a6d41fa5 = addyd53b59933f6c3f2e8b59f1b4a6d41fa5 + 'vanssports' + '.' + 'com'; 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. The height is approximately six inches higher than with a propeller. Place the bracket on the transom to the left of the main outboard or rudder. Beginning boaters should be aware of the boats measurements. 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). Whether you already own a boat or looking for your first watercraft we are here to service your needs. The outboard comes with mounting holes and brackets. Mounting the motor lower on the boat transomcan createexcessive spray, increase case drag, reduce underwater clearance, and negatively impact faster boats. Pad to bottom of Its still smart to measure it yourself though, just in case, the design changed over the years. You dont have to be a mathematician to determine the correct boat transom angle. Also, how do you determine the length of an outboard transom? I show you how to consistently measure your prop to pad height. I would also recommend finding your maximum horsepower rating which is located on the yellow coast guard tag towards the back of your boat. var addy_textd53b59933f6c3f2e8b59f1b4a6d41fa5 = 'info' + '@' + 'vanssports' + '.' + 'com';document.getElementById('cloakd53b59933f6c3f2e8b59f1b4a6d41fa5').innerHTML += ''+addy_textd53b59933f6c3f2e8b59f1b4a6d41fa5+'<\/a>'; https://www.bornagainboating.com/Get Your Born Again Boating Clothing! I hope this helps someone out in their search for a new or newer outboard this season. Engine Oil Mixing Ratio Fuel 50: Engine Oil 1. Depending on the manufacturer, size names might change. Read the following to get the optimal shaft length for outboard motors! Check the literature about your model boat online, and you may be surprised to find that the number is published for you. On this type of boat, if you are in doubt, default to the longer-shafted outboard. Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. s.setAttribute("type", "text/javascript"); These are vertically aligned so the boater can make adjustments. By clicking Accept, you consent to the use of ALL the cookies. A deep Vee hull will result in a different measurement than a flatter . Or it can have an angle degree as high as 30. It also cuts into speed and fuel efficiency. maxMicroAmount: 0.0, Industry standards dictate that for short shaft engines the transom height should be 15. As a result, the issue is whether my boat need a short shaft or long shaft motor. h[0].appendChild(s); To achieve this, the motor itself has to be attached at the correct height. 1 0 obj Is my outboard long or short shaft? Now that you have a better understanding of boat transom heights its time to take out the ruler and get the perfect measurements. 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. This was the height of my 225 Yamaha on my TR21 e-mail Copyright 1999-2023 Boats Group. gtag('js', new Date()); Performance cookies are used to understand and analyze the key performance indexes of the website which helps in delivering a better user experience for the visitors. 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. Should I take the raft onto the water and measure the exact distance from the top of the transom to the water line? And the rule of thumb is that you should keep the cavitation plate level with the bottom or keel of the boat. This cookie is set by GDPR Cookie Consent plugin. Pretty easy to figure out but like I said its crucial to pairing a motor with a boat. It is extremely important that the boater understands the significance of the transoms height. 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. from the transom. Finding the right size is a matter of looking at what youve got and taking out the measuring tape. 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. Place the clubs bottom on the ground as though it were going to be used to strike a golf ball. steel ruler, etc. %PDF-1.7 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. 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. Boat Transom Heights The Beginners Guide, Buying a boat can be an exciting purchase. Why wont Touch ID be under the screen in the iPhone 15 and iPhone 16? The point where these measurements intersect is your centerline. If it measures anywhere from 17" to around 22", then your going to want to go with a long shaft motor. Height Measurement: Recommended Shaft Length: 14" - 17.25" 15" Shaft (Short) 17.25" - 19.5" Varies by application 19.5" - 22.5" Long shafts are 20-inches long. 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. bracket forward with a straight edge to where you can then measure up Actual shaft length is 21.5" on those. This is also known as the shaft length. })(); Where Onboard a Boat is the Transom Located and More About Transom Heights A propeller operates based on the height of the transom. A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. 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. This also means it can affect the safety of the boat. Doing this can have adverse effects. var BCData = {"csrf_token":"d7ecb6b56891bb66aee12dbc01a80162b3ed582c1acbe30f16fc9f1b2abc362f"}; Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. 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. So how to determine the outboard shaft length? Buying a boat can be an exciting purchase. The vertical distance between the interior of the clamp and the cavitation plate is the shaft length specified by the outboard manufacturer. 1855 Alpine Avenue NWGrand Rapids, MI 49504This email address is being protected from spambots. If possible for your peace of mind and not let down that magnificent purchase opportunity, place that 08 kicker at back transom and test for yourself. As mentioned above, the operation of the propeller relies on the transom height. I live for the weekends when I can go out on the water and escape the stress of life on land. Higher mounting decisions should be left to the professionals. Oftentimes you will want to adjust the outboard shaft length in order to improve the boat performance such as speed. High powered boats usually only come in long and extra-long variants. Among them will be first-timers or those who have recently purchased their boats. The propellers will also have trouble reaching the water. The center is the point where your outboard motor is (ideally) located. On the downside, a higher mount can interfere with the boaters steering capabilities. If you went too long it would still work but it may lack in performance. displayMicroOffers: false, The boater must also consider if the boat transom support is designed to bear the weight of a higher mount. Gear case sits just below or at the hull depth due to the deep v. The transom is the back of the boat where the motor is hung. What Types of Documents Can be Sent to your Kindle Library? 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. actually have the propshaft above the pad.). It is very versatile as it generally . Measure from the top of the straight edge to the center of the front Problems with getting the ventilation plate too low include slower hole-shot and lower top-end speeds. 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. The average transom angle is around 14 degrees. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. It will ensure that the outboards trim will be effective, and it will save you gas too. For really big boats, the biggest and baddest six- or eight-cylinder outboards can have extra-extra long shafts up to 30 inches. jackplate to a point level with the top of the transom. If it measures 15" or with in a inch of that you will need a short shaft outboard. On the downside, a higher mount can interfere with the boaters steering capabilities. You also might not be able to lift the outboard out of the water entirely for storage. straight edge on the top of the transom to "extend" it out To do so, take a measurement from the very top to the very bottom of the transom in the precise center. Generally, short shaft outboards are 15 inches, long shaft outboards are 20 inches, and extra-long outboards are 25 inches. The engine must be linked to the transom at the proper height for a propeller to best meet specific boating demands. 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. Knowing how this can affect the overall operation of the boat is a factor to be considered. I also love helping others, which is why I created this website. Higher mounting decisions should be left to the professionals. var h = d.getElementsByTagName("head"), 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. boats.com, 1221 Brickell Avenue, 23rd Floor, Miami, FL 33131, USA. relation to pad Two years ago, I bought a Boston Whaler to fish off the coast. resting on the transom if you had the motor all the way down on the boat This alone can outweigh the negatives when deciding to adjust the mount upwards. Now that you have a better understanding of boat transom heights its time to take out the ruler and get the perfect measurements. The boat transom can be flat with zero degree angles. The transom in a boat today is a place to hang your outboard motor. Make sure that you are measuring straight up, at a 90 degree angle to Some outboards have a serial number that tells you which shaft length to go for. This cookie is set by GDPR Cookie Consent plugin. If you have a question or need additional information. 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. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. 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. function loadScript(script) { Your goal is to measure how the outboard will sit, so start from the clamping plate and follow the centerline of the hull. 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.