There is a simple test to see if your outboard motor is set at the best height. He is a 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. The prop will be in cleaner, harder water as it advances farther aft, making it more efficient. (updated Attention: Remember to measure the outboard shaft length straight up and down instead of measuring along the transom. The motor is what powers the boat so the two go hand-in-hand. 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. Amazon has plate extensions to allow adjustments without buying a new motor: T-H Marine Jack Plate Extension. With the long side (22 1/2), place a carpenters square ) in opposition to the keel. This is also known as the shaft length. Here we will guide you in how to get the right boat transom height. (Putting a Most of the time, adding a hydrofoil to an outboard improves performance. "brackets". If you have a jackplate, you may have to get a bit creative in your No one wants to have issues with a new transom or boat repairs. Outboards designed for saltwater applications usually have longer shafts. You may wonder how deep your prop should be in the water. 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. High powered boats usually only come in long and extra-long variants. (3) Move horizontally across the chart until you hit the graph curve. With some boats I have a pretty good idea as to what length motor should be hung on them. How high exactly do you have to raise the transom?-. MPW eBay Store - Thousands of New OEM Old Stock Parts! I believe 20 to 21 inches is the optimum length for a lengthy shaft. 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. There are a series of four to six holes at the top of the bracket, and the lower bolts actually fit into slots. mpeInit(); Bass boats, ski boats, or center cockpit vessels will want to double-check their measurements to get it just right. Theyre also useful if the back of your boat has a non-standard measurement. ensure that your measurement is accurate. Check the literature about your model boat online, and you may be surprised to find that the number is published for you. Pretty easy to figure out but like I said its crucial to pairing a motor with a boat. Mounting the motor lower on the boat transom can create excessive spray, increase case drag, reduce underwater clearance, and negatively impact faster boats. Here we look at the effects of standard, lower and higher mounting. Pad to bottom of Engine Oil Mixing Ratio Fuel 50: Engine Oil 1. If you go too short your more than likely going to cavitate and loose power. height (that I'm aware of); probably the most common is: In lower mounting, the engine is set lower than the recommended standard. This is simply a measurement taken from the top of the transom (top of your motor will be higher.) 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. up to the bottom of the motor brackets, (as in #1). Also, how do you determine the length of an outboard transom? His works have appeared in regional newspapers in North Dakota and in "North Dakota Horizons" and "Cowboys and Indians" magazines. to where the brackets were actually resting on the transom. What the relationship to the pontoons is, I couldn't say. Mounting the outboard a little bit lower than the standard point could avoid the possible ventilation and slip on acceleration. Ten years ago I bought my first boat. <>/ExtGState<>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 595.2 841.8] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> Having the cavitation plate too low will cause excess drag and reduced performance at high speeds. However, you will need an understanding of how the degrees will alter the boats usability. The height is approximately six inches higher than with a propeller. Increased RPM and additional horsepower feed the need for speed. The clamp bracket is designed so that the engine's mounting height on the transom can be adjusted higher than standard. You also might not be able to lift the outboard out of the water entirely for storage. This will ensure the best performance. As summer approaches there will be more boaters taking to the water. Any owner seeking the last bit of speed from an outboard-powered boat should grab a yard stick. The most common percent angle is probably 12, however spec sheets for O/B and I/O boats may show 10 percent, 12 percent, and 14 degrees. Your email address will not be published. If the height of the boat transom is off it can cause major issues. Another important measurement is the transom angle. The transom angle is the vertical incline of the transom and is measured in degrees. bracket. var BCData = {"csrf_token":"d7ecb6b56891bb66aee12dbc01a80162b3ed582c1acbe30f16fc9f1b2abc362f"}; I mean it is better to be safe than sorry, am I right? It doesnt matter if you have a fiberglass boat, bay boat, big or small boat. 12 Small Fishing Boat Accessories to Buy Today. ), and place it on the bottom of the pad in the center. Read the measurement on the transoms bottom. s.setAttribute("href", "https://cdn.paytomorrow.com/css/pt-mpe.min.css"); Over time, Boating Hub has grown into a resource for boating enthusiasts around world. xmlHttp.open('POST', 'https://bes.gcp.data.bigcommerce.com/nobot'); A reversetransom that sits too high can impact the propellers of the motor and motor bracket. Boats that use longer outboard shafts include: of the "bullet" on your lower unit. If your boat planes, pay extra attention to getting the shaft length as close to perfect as possible. Attention: Remember to measure the outboard shaft length straight up and down instead of measuring along the transom. This could also affect your travelling capabilities on the boat trailer. There are instances where a lower mount may be okay. parallel with the straight edge. But opting out of some of these cookies may affect your browsing experience. If you decide to make adjustments, please consult a marine engine dealer about the boatdesign. What's the best height for my boat motor? 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. Outboard shaft length plays a crucial role in the performance of your boat. 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. As a yacht designer and boater, I prefer longer shafts. minAmount: 300.0, If the propeller fails to ventilate, the motor is mounted to low. This restriction includes most fishing boats and longer sailboats. Problems with getting the ventilation plate too low include slower hole-shot and lower top-end speeds. 7. You'll need a short shaft outboard if it's 15 or less than an inch shorter. You must be still in the blue about that matter. You can order an outboard in lengths ranging from 15 inches to 30 inches, depending on its power output and possible uses. Thats a fairly simple list of symptoms, but if your motor is too low, youll probably notice at least one of them. You can use a longer shaft than recommended and your boat will work fine. 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. Wherever the outboard clamping bracket is, use this as the basis for measurement. This provides seaworthiness and offers maximum protection from large seas. Small motors built for sailboats might come in a unique configuration with an extremely long shaft since these are mounted higher off the water. Take a long straight edge, (long carpenter's level or long Keith Allen, a 1979 graduate of Valley City State College, has worked at a variety of jobs including computer operator, medical clinic manager, radio talk show host and potato sorter. }) } }); })(document); C Cheaptoon Cadet Joined Aug 4, 2010 Messages 28 Aug 24, 2010 #4 Re: Motor height on pontoon? With such an important, long-term, and expensive upgrade, its never a bad idea to double-check. This alone can outweigh the negatives when deciding to adjust the mount upwards. displayMicroOffers: false, These are vertically aligned so the boater can make adjustments. Boat hulls are designed in three basic types that range from slow displacement and semi-displacement hulls to the fastest planing hulls. trimming the motor out by one-half to full trim. Repowering your boat is one of the most expensive upgrades you can make. Increased RPM and additional horsepower feed the need for speed. Your email address will not be published. out the confusion. Industry standards dictate that for short shaft engines the transom height should be 15. 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. endobj bassboat can be a bit confusing at times; hopefully this will help sort If the propeller fails to ventilate, the motor is mounted to low. The how to measure the shaft length of an outboard motor is a question that many people have asked. 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. the propshaft below or above the pad. When trimming your motor, they provide you a greater bow response. Is my outboard long or short shaft? My family and I used it to fish, ski (yes, you can ski behind a pontoon boat), and cruise the lakes near our home. This illustration depicts four different outboard mounting height options (courtesy Mercury Marine). You will also risk hitting bottom or submerge objects more frequently such as rocks or logs. Thats it. Buying a boat can be an exciting purchase. All boats are different, and the motor manufacturers produce a variety of standard lengths. You can find your Mercury outboard model code on an ID plate or sticker. var ptScript = "https://cdn.paytomorrow.com/js/pt-mpe.min.js"; A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. The amount of degrees the transom leans back from vertical is known as the transom angle. It is extremely important that the boater understands the significance of the transom's height. It was a 23-foot Crestliner Grand Cayman pontoon boat. addyd53b59933f6c3f2e8b59f1b4a6d41fa5 = addyd53b59933f6c3f2e8b59f1b4a6d41fa5 + 'vanssports' + '.' + 'com'; There are instances where a lower mount may be okay. stream Long shafts are 20-inches long. How the outboard will sit on the back of the boat depends on how the transom is designed. }, 100); Raising an outboard higher on the transom can reduce drag and raise top speed. displayPrimeOffers: true, This could also effect your travelling capabilities on the boat trailer. 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). publicId: "32bf3437d1346295e03ebcf545f9c839", A transom saver, which can change the spacing between the lower unit and the trailer, negates some of the support. The boat transom can be flat with zero degree angles. All things considered, sticking with the industry standard is best for the beginner. As a result, the issue is whether my boat need a short shaft or long shaft motor. Analytical cookies are used to understand how visitors interact with the website. In step 3, add another 10 cm (4") to the previous calculation in order to develop the ideal shaft length. Why wont Touch ID be under the screen in the iPhone 15 and iPhone 16? I mean, who wants to purchase something as expensive as an outboard to only realize you bought the wrong one. But, how do you measure it? Because of the increased friction, cavitation reduces efficiency. This cookie is set by GDPR Cookie Consent plugin. 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. Other factors to consider when determining the mounting height of an outboard are related to performance. It will ensure that the outboards trim will be effective, and it will save you gas too. Remanufactured 4 Cylinder 4-Stroke Cylinder Heads, Remanufactured 6 Cylinder 4-Stroke Cylinder Heads, Trim Relays, Trim Solenoids & Sending Units, Remanufactured V6 & V8 4-Stroke Cylinder Heads, Volvo Cobra SX Bearings and Bearing Carriers, Volvo Cobra SX Driveshaft, U-Joints & Parts, Volvo Cobra SX Transom Assembly & Bellows. On the downside, a higher mount can interfere with the boaters steering capabilities. Shaft lengths are available in increments of 5. 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. 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. Each one has a totally different effect on the boats performance. Always weigh the risks of making adjustments. Expectedly, when the transom angle is zero, it means it is flat. x\[D~OUCO6[j](l%ay <8cylY{.L2s#]~U6A|Wj]-oo|mubqY6wbY_|!>Z8(RB:RHeTzOGO_=~t\ What is Transom Height? If you went too long it would still work but it may lack in performance. Cutting the transom down is the only legal method to utilize a short shaft engine on a tall transom. The transom is the "back wall" of your boat, the most rearward part of your hull. This is a measurement that has been used for BassCats, I'm Outboard motors can be fitted to a variety of boats, so manufacturers have standardized their engines to go on virtually anything. At least if its too long you can raise the motor or "build up" your transom. | Sitemap, The Marine Parts Warehouse Outboard Museum, OBR Powerhead / Shortblock Warranty Claim Form, Remanufactured vs. Copyright 2017 Dealer Spike All Rights Reserved. #1: Height It is where the outboard is mounted, and some boat owners place the name of the boat. window.dataLayer = window.dataLayer || []; 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. 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. The clamp bracket on the latest Mercury Four-Stoke-model outboards has five mounting bolt holes spaced .75 inches apart. Say the 20 shaft is a long shaft length for gas engines, but it is a short shaft length for electric outboard motors. 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. If you decide to make some custom adjustments we have theexperience and know-howto make it happen. Its important to note that manufacturers call their models different things. Workboats, sailboats, and displacement-hulled boats fall into this category. 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. This is somewhat similar to #2, in that you are again measuring with a The cookie is used to store the user consent for the cookies in the category "Other. (function () { Other uncategorized cookies are those that are being analyzed and have not been classified into a category as yet. The cookie is used to store the user consent for the cookies in the category "Analytics". The collapsing bubbles are loaded with extremely low-pressure water vapor, which causes damage to a variety of surfaces as they collapse. If you are looking to repower, they may be able to offer some sage advice. var path = 'hr' + 'ef' + '='; However, the motor should not be raised more than 5 inches above the standard position. The lowest point will likely be directly under your drain plug if youve got one. 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. Re: Dinghy with a long shaft motor? gtag('js', new Date()); 2019s List of the Best Recreational Pontoon Boats for Sale. If it measures 15" or with in a inch of that you will need a short shaft outboard. Chances are the boat was designed with a specific size of outboard in mind. This measurement is primarily designed for single motor propulsion. A deep Vee hull will result in a different measurement than a flatter . endobj For over five years he has worked as a newspaper reporter and historic researcher. To break it down a bit more for you: Short shafts are 15-inches long. The first step is to determine the height of your boat's transom. %PDF-1.7 a Detwiler manual jackplate. 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 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). Now that you have a better understanding of boat transom heights its time to take out the ruler and get the perfect measurements. Engine Oil Type Genuine or Recommended 2str Engine Oil. Outboard Motor Shaft Length: How do I measure? It moves an outboard up and down to optimize performance and enable a boat to venture into shallower water than it might otherwise. But in many cases, its a little more complicated than that alone. measuring; you may have to "extend" the flat part of the (In the case of the faster *The Factors indicates the adjustment affected by on your boat type, the outboard working environment, and the transom distance as discussed above. Another important measurement is the transom angle. 2 0 obj Trimming in, trimming down, and trimming out are all terms that a beginning boater should learn. boats.com, 1221 Brickell Avenue, 23rd Floor, Miami, FL 33131, USA. Measure from there down to the top of the cavitation plate, also known as the anti-ventilation plate. The boat transom can be flat with zero degree angles. want to measure from the transom to the flat part of this bracket, Step 3: Add another 10 cm (4'') to the previous calculation for the final ideal shaft length. Finding the right size is a matter of looking at what youve got and taking out the measuring tape. Or it can have an angle degree as high as 30. #2. Lubrication System Engine Oil Mixed Gasoline. 5/rC,aQhsK@Q. When the boattransom is too low, the motor could end up underwater. A: The short answer is Yes. It can also improve the experience of driving a faster boat. Check out the Westshore Marine & Leisure Youtube page! You also have the option to opt-out of these cookies. mpeSelector: ".pt-mpe", Extra-extra long shafts are 30-inches long. To measure the transom height, measure from the center on for transom (rear of the boat). No one wants to have issues with a new transom or boat repairs. Among them will be first-timers or those who have recently purchased their boats. And the rule of thumb is that you should keep the cavitation plate level with the bottom or keel of the boat. <> To do so, take a measurement from the very top to the very bottom of the transom in the precise center.
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