Higher mounting decisions should be left to the professionals. Finding the right size is a matter of looking at what youve got and taking out the measuring tape. The motor is what powers the boat so the two go hand-in-hand. x\[D~OUCO6[j](l%ay <8cylY{.L2s#]~U6A|Wj]-oo|mubqY6wbY_|!>Z8(RB:RHeTzOGO_=~t\ On this type of boat, if you are in doubt, default to the longer-shafted outboard. Then open up the clamp bucket. Engine Oil Mixing Ratio Fuel 50: Engine Oil 1. would be more accurate.) If you have a question or need additional information. Engine Oil Type Genuine or Recommended 2str Engine Oil. Industry standards dictate that for short shaft engines the transom height should be 15. The Effects of Standard, Lower and Higher Mounting. As a result, the issue is whether my boat need a short shaft or long shaft motor. So from there, I will try to help out by asking questions about your boat such as what type it is and the length. The motor length corresponds to the transom height of the boat, measured from the keel to gunwale at the transom. Determining Your Boat Transom Angle The transom angle - commonly measured in degrees - is the transom's vertical inclination. With a jack plate, you can mount it exactly where you want it. resting on the transom if you had the motor all the way down on the boat Boats with more engine power and weight require longer shaft outboards for better balance. Wherever the outboard clamping bracket is, use this as the basis for measurement. Shaft lengths are available in increments of 5. })(); Trimming in, trimming down, and trimming out are all terms that a beginning boater should learn. If youd like to see this in video format, skip to 0:44 in the below YouTube Video: Is it OK to put a long shaft outboard on a boat thats rated for a short shaft? For really big boats, the biggest and baddest six- or eight-cylinder outboards can have extra-extra long shafts up to 30 inches. This is simply a measurement taken from the top of the transom (top of What Kind of Fuel Does Your Marine Engine Need? There are instances where a lower mount may be okay. Always weigh the risks of making adjustments. Should I take the raft onto the water and measure the exact distance from the top of the transom to the water line? Whether you already own a boat or looking for your first watercraft we are here to service your needs. 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. What types of boat need an extra long shaft? 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. If it measures 15" or with in a inch of that you will need a short shaft outboard. Well, raising the outboard motor can be an easy task for you. The collapsing bubbles are loaded with extremely low-pressure water vapor, which causes damage to a variety of surfaces as they collapse. var prefix = 'ma' + 'il' + 'to'; It does not store any personal data. Take your time and understand your boat and your entire transom. Knowing how this can affect the overall operation of the boat is a factor to be considered. Generally, short shaft outboards are 15 inches, long shaft outboards are 20 inches, and extra-long outboards are 25 inches. August 9/08). If your boat is newer and the manufacturer is still in business, you might also want to try to give them a call. 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. The cookie is used to store the user consent for the cookies in the category "Performance". Simply start with the engine in idle, followed by, If you decide to make some custom adjustments we have the. When the jet drive is on the motor, set the height so that the leading edge of the intake is flush with the boat bottom. Its where the outboard motor is attached, and its also where some boat owners put the boats name. 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. This could also effect your travelling capabilities on the boat trailer. If you are running a slower boat, the exact location of the ventilation plate is less important. Attention: Remember to measure the outboard shaft length straight up and down instead of measuring along the transom. The height of the boat transom dictates the size of the outboard motor. How to Measure Transom Height For vessels with transom-mounted outboards, you can easily figure out which type of outboard you need to get. Save my name, email, and website in this browser for the next time I comment. Smaller boats may use adjustable jack plates that can be changed to fit any outboard. In the case of a dinghy or johnboat, this point may be the top of the transom. bassboat can be a bit confusing at times; hopefully this will help sort 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. (updated Whether you already own a boat or looking for your first watercraft we are here to service your needs. Actually there is no designated letter for short shaft. As you can see, the measurement is about 2 1/2". While this is the case there is certain saltwater motors that are extra extra long at 30 and 35 shaft. This placement is not only recommended but it will give you the best performance compared to something that is too long or too short. Among them will be first-timers or those who have recently purchased their boats. One of the great things about an outboard motor is how versatile it is. Measuring the shaft length can be done in various ways, but the most common way is by using a tape measure. With more than a decade of experience cruising the lakes in my Crestliner Grand Cayman pontoon boat and my Boston Whaler, I now want to share everything I've learned with my community here at Boating Hub. Recommended Engine Oil 2-Stroke Outboard Motor Oil. Outboards designed for saltwater applications usually have longer shafts. They operate as a planing surface, allowing your boat to climb to the top more quickly. your motor will be higher.) At least if its too long you can raise the motor or "build up" your transom. This alone can outweigh the negatives when deciding to adjust the mount upwards. What is the Virtual Sundance Film Festival? Owners of bass boats, RIBs, or offshore fishing boats need to get this right. You dont have to be a mathematician to determine the correct boat transomangle. But in many cases, its a little more complicated than that alone. If you have a jackplate, you may have to get a bit creative in your Make sure that you are measuring straight up, at a 90 degree angle to Raising the motor increases the speed of the boat while decreasing the effort needed to turn the boat. %PDF-1.7 The outboard comes with mounting holes and brackets. With the motor trimmed so that the propshaft is parallel to the keel, the anti-ventilation plate should be just about even with your straight edge, and thus even with the boat bottom at the keel. It is very versatile as it generally . parallel with the straight edge. Anything bigger than that your obviously going to need an extra long shaft. 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}'); 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. Save my name, email, and website in this browser for the next time I comment. It was a 23-foot Crestliner Grand Cayman pontoon boat. He is a 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. If measuring an existing outboard: Measure from the inside top of mounting bracket down to anti-cavitation plate above propeller (this is the largest plate/fin directly above the propeller). 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. How Transom Height Is Measured 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. It moves an outboard up and down to optimize performance and enable a boat to venture into shallower water than it might otherwise. Boat transom angles play a pivotal role in the flexibility of the boats trimming abilities. The transom angle is the vertical incline of the transom and is measured in degrees. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. function loadScript(script) { Each one has a totally different effect on the boats performance. Learn More About Your Boats Systems By Joining The Born Again Boating Academy! Boaters who consider going with a higher mount can see increased speeds. Outboard shaft length plays a crucial role in the performance of your boat. Variables to consider when determining the mounting height include the size and style of the boat and the length of the outboard motor's shaft. var BCData = {"csrf_token":"d7ecb6b56891bb66aee12dbc01a80162b3ed582c1acbe30f16fc9f1b2abc362f"}; If youre looking for a bracket that can handle motors of up to 10/15 horsepower, go no further. 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("href", "https://cdn.paytomorrow.com/css/pt-mpe.min.css"); Beyond motorboats designed for large outboards, you will see outboards hanging on the sterns of everything from small canoes to large cruising sailboats. There Industry standards dictate that for short shaft engines the transom height should be 15. Step 2: Three Variables to Consider By clicking Accept, you consent to the use of ALL the cookies. Safely but briskly accelerate. 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. If you go too short your more than likely going to cavitate and loose power. Also, the boat will be more likely to hit bottom or submerge objects such as rocks or logs. This is probably the worst case scenario out of the two. This is measured by the propeller shaft being parallel to the vessels bottom. Basically, there are three main ways to measure motor This cookie is set by GDPR Cookie Consent plugin. var ptScript = "https://cdn.paytomorrow.com/js/pt-mpe.min.js"; To do so, take a measurement from the very top to the very bottom of the transom in the precise center. This is the dimension you'll need when selecting a width for your outboard motor's mounting bracket. They keep water out of your prop and increase water pressure in the system. This alone can outweigh the negatives when deciding to adjust the mount upwards. primeApr: 12.99, To achieve 35 mph with a 6 hp engine, the total weight is 135 lbs (boat motor fuel passengers). Any questions? Picking the right shaft length is mostly a factor of the transom height or the back of the boat. 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. Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. A yardstick will help you determine if your outboard engine is at the right height. d.addEventListener("DOMContentLoaded", function (e) { I show you how to consistently measure your prop to pad height. Take the center measurement from the top to the bottom of the hull. Gear case sits just below or at the hull depth due to the deep v. Boats that use longer outboard shafts include: Doing this can have adverse effects. As summer approaches there will be more boaters taking to the water. Place the bracket on the transom to the left of the main outboard or rudder. I would ask you to go back and measure the transom of your boat. It can also improve the experience of driving a faster boat. This allows the engine to idle without the flow of the exhaust being restricted. There are 2 steps to help get a relatively accurate figure. 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. In the second photo, we've measure down from the top of the Detwiler Is my outboard long or short shaft? Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. and I'll explain it better, (or point you to someone that can help. maxTerm: 36, The boater must also consider if the boat transom support is designed to bear the weight of a higher mount. My family and I used it to fish, ski (yes, you can ski behind a pontoon boat), and cruise the lakes near our home. s.setAttribute("rel", "stylesheet"); It is extremely important that the boater understands the significance of the transom's height. He is also a certified marine technician and the author of a popular text on writing local history. This is measured by the propeller shaft being parallel to the vessels bottom. Now that you have a better understanding of boat transom heights its time to take out the ruler and get the perfect measurements. Check the literature about your model boat online, and you may be surprised to find that the number is published for you. var addyd53b59933f6c3f2e8b59f1b4a6d41fa5 = 'info' + '@'; Youll need a short shaft outboard if its 15 or less than an inch shorter. Read the following to get the optimal shaft length for outboard motors! The pressure behind your hand dropped as you slid your hand back and forth through the water. These allow the mounting of a standard length outboard behind the transom. 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. Re: Dinghy with a long shaft motor? Lubrication System Engine Oil Mixed Gasoline. However, the motor should not be raised more than 5 inches above the standard position. This website uses cookies to improve your experience while you navigate through the website. Typical motor lengths include the following. Another important measurement is the transom angle. For vessels with transom-mounted outboards, you can easily figure out which type of outboard you need to get. You'll need a short shaft outboard if it's 15 or less than an inch shorter. Ideally, you want the outboards cavitation plate, also called the anti-ventilation plate, to be at the same level as the bottom of your hull. As with anything, there are exceptions to the rule. AztH ^zv_ cT,E1K/rAB54| e-mail All boats are different, and the motor manufacturers produce a variety of standard lengths. When trimming your motor, they provide you a greater bow response. The transom is the "back wall" of your boat, the most rearward part of your hull. 2019s List of the Best Recreational Pontoon Boats for Sale. trimming the motor out by one-half to full trim. A: The answer varies by boat, but here are some rules of thumb for matching a short shaft outboard to your boat. (3) Move horizontally across the chart until you hit the graph curve. The cookies is used to store the user consent for the cookies in the category "Necessary". The motor is what powers the boat so the two go hand-in-hand. 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. loadScript(ptScript); }) } }); })(document); disregard the downward pointing "hooks" at the front of the This, however, is not recommended for the beginning boater. 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. Outboard motors can be fitted to a variety of boats, so manufacturers have standardized their engines to go on virtually anything. stream Check out some hot FAQs to help you get the proper outboard shaft lengths. Higher mounting decisions should be left to the professionals. The vertical distance between the interior of the clamp and the cavitation plate is the shaft length specified by the outboard manufacturer. Since the length of the shaft of your outboard is associated with the size boat, smaller engines will generally have shorter shafts. relation to pad Or it can have an angle degree as high as 30. document.getElementById('cloakd53b59933f6c3f2e8b59f1b4a6d41fa5').innerHTML = ''; 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. Although the longer outboard shaft length can lead to lower speed and more drag, the boat can push a heavier load. Mounting the motor lower on the boat transom can create excessive spray, increase case drag, reduce underwater clearance, and negatively impact faster boats. If it measures between 17 and 22, youll want to go with a long shaft motor. This distance is very important to the performance of you boat. Tightening Torque for Engine. No matter what size of boat you are running, one of the most critical choices you can make when buying an outboard motor is the shaft length. since 1986. motor brackets Thats it. To do so, take a measurement from the very top to the very bottom of the transom in the precise center. All rights reserved. Outboard Motor Shaft Length: How do I measure? Step 2 requires the propeller's radius (check the user manual and then the technical drawing). Among them will be first-timers or those who have recently purchased their boats. See diagram below. The cookie is used to store the user consent for the cookies in the category "Other. If the height of the boat transom is off it can cause major issues. So how to determine the outboard shaft length? I hope this helps someone out in their search for a new or newer outboard this season. If the propeller fails to ventilate, the motor is mounted to low. "brackets". The brackets can add 1 inch to the overall mounting height of the outboard. Doing this can have adverse effects. Since the ventilation plate & foil are burried under water it is obviously too low. Attention: Remember to measure the outboard shaft length straight up and down instead of measuring along the transom. These are vertically aligned so the boater can make adjustments. (function () { One of the main concerns is causing the engine to overheat if not enough water reaches the engine to keep it cool. Some fishing boats can handle the motor being underwater. There are a series of four to six holes at the top of the bracket, and the lower bolts actually fit into slots. Before we get started lets see what a boat transom is and what it does. Cavitation is when the propeller is out of the water due to the boat forming a wake of "air bubbles" or "vapor cavities" around the prop. Generally, the anti-ventilation plate on most engines is aligned with the bottom of the vessel. Measure straight down to the lowest point on the hull. The propellers will also have trouble reaching the water. 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. What matters is the actual measurement in the specifications, not the name. steel ruler, etc. This cookie is set by GDPR Cookie Consent plugin. These cookies will be stored in your browser only with your consent. The boat transom can be flat with zero degree angles. PayTomorrow.mpeInit({ Some outboards have a serial number that tells you which shaft length to go for. With it comes a lot of responsibility and new things to learn includingboat maintenanceand boat basics. And the rule of thumb is that you should keep the cavitation plate level with the bottom or keel of the boat. Or it can have an angle degree as high as 30. a Detwiler manual jackplate. A deep Vee hull will result in a different measurement than a flatter . gtag('js', new Date()); var h = d.getElementsByTagName("head"), Displacement hulled vessels like sailboats and workboats can benefit from a little more space between the hull and cavitation plate, but not much. You reply, "Im not sure, I think its a long". This is handy if youre shopping for second-hand outboards or looking to sell the one that came with your boat. His works have appeared in regional newspapers in North Dakota and in "North Dakota Horizons" and "Cowboys and Indians" magazines. (In the case of the faster Then test the boat and adjust the height, if necessary . (127 mm). In lower mounting, the engine is set lower than the recommended standard. Doing so, will put the propeller right below the boat. There is a simple test to see if your outboard motor is set at the best height. 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. 1 0 obj 4 0 obj What are Apple Podcasts Subscriptions and Channels? In the photo above, we've measured from the motor bracket to the top of Increased RPM and additional horsepower feed the need for speed. Happy boating! the aluminum plate on top of the transom), to the bottom of the motor endobj publicId: "32bf3437d1346295e03ebcf545f9c839", MarinePartsMan.com also says that V6 bass-boat engines have a 20-inch shaft. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. This restriction includes most fishing boats and longer sailboats. <>/Metadata 127 0 R/ViewerPreferences 128 0 R>> This cookie is set by GDPR Cookie Consent plugin. It can also improve the experience of driving a faster boat. And thats usually the case since the electric outboards are designed with larger and more efficient propeller that needs longer shaft. Your email address will not be published. On the downside, a higher mount can interfere with the boaters steering capabilities. 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. Allowing the propeller to pull water from underneath and push it out behind the boat. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. While this is the case there is certain saltwater motors that are extra extra long at 30 and 35 shaft. However, your boat will have slightly more drag which will reduce your maximum speed. Having the cavitation plate too low will cause excess drag and reduced performance at high speeds. 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. You must be still in the blue about that matter.

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