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

This was the height of my 225 Yamaha on my TR21 August 9/08). This is a measurement that has been used for BassCats, I'm Check the literature about your model boat online, and you may be surprised to find that the number is published for you. Check out the Westshore Marine & Leisure Youtube page! 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. They operate as a planing surface, allowing your boat to climb to the top more quickly. I believe 20 to 21 inches is the optimum length for a lengthy shaft. Then finally test your outboard, if the mount is perfect. It is where the outboard is mounted, and some boat owners place the name of the boat. This, however, is not recommended for the beginning boater. boats.com, 1221 Brickell Avenue, 23rd Floor, Miami, FL 33131, USA. Its important to note that manufacturers call their models different things. However, there may be times when a boater strays away from these recommendations. As with anything, there are exceptions to the rule. xmlHttp.open('POST', 'https://bes.gcp.data.bigcommerce.com/nobot'); I hope this helps someone out in their search for a new or newer outboard this season. Offshore vessels are often equipped with a large mounting bracket so that the transom can be left at full height. As summer approaches there will be more boaters taking to the water. He is also a certified marine technician and the author of a popular text on writing local history. Take your time and understand your boat and your entire transom. disregard the "hooks" at the front of the Mounting the outboard motor in accordance with the industry standards is important. All rights reserved. Will Charpentier is a writer who specializes in boating and maritime subjects. Remember, if you use a longer outboard shaft than you need you will be increasing your draft. Since the length of the shaft of your outboard is associated with the size boat, smaller engines will generally have shorter shafts. Generally, the anti-ventilation plate on most engines is aligned with the bottom of the vessel. The height of the boat transom dictates the size of the outboard motor. How Transom Height Is Measured var prefix = 'ma' + 'il' + 'to'; Here we will guide you in how to get the right boat transom height. #3. 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. If you have a question or need additional information. Long shafts are 20-inches long. 2019s List of the Best Recreational Pontoon Boats for Sale. The engine must be linked to the transom at the proper height for a propeller to best meet specific boating demands. Other boats that need extra long shafts are: Read my other articles on outboard motors. Raising the motor increases the speed of the boat while decreasing the effort needed to turn the boat. displayPrimeOffers: true, For example, you can have the Mercury outboard shaft length by model code. This alone can outweigh the negatives when deciding to adjust the mount upwards. All you need to do is measure how much to rise. Chances are the boat was designed with a specific size of outboard in mind. debugMode: false, Small portable outboards ranging from 2 to 20 horsepower are usually sold only in short or long shaft versions. })(); You'll need a short shaft outboard if it's 15 or less than an inch shorter. 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}'); Or measure from the main engine prop up to the water line? ), Al Shields (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. His works have appeared in regional newspapers in North Dakota and in "North Dakota Horizons" and "Cowboys and Indians" magazines. Among them will be first-timers or those who have recently purchased their boats. out the confusion. primeApr: 12.99, Take a long straight edge, (long carpenter's level or long trimming the motor out by one-half to full trim. To do so, take a measurement from the very top to the very bottom of the transom in the precise center. What Kind of Fuel Does Your Marine Engine Need? Here we will guide you in how to get the right boat transom height. 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. Use the mounting bracket on the motor to know where it will sit on the boat. I run a 9.9 Mercury Bigfoot 20" shaft off the swim platform of my 89 Trophy 2160. 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. <> To measure the transom height, measure from the center on for transom (rear of the boat). If it measures 15" or with in a inch of that you will need a short shaft outboard. 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. Since the ventilation plate & foil are burried under water it is obviously too low. 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. C Cheaptoon Cadet Joined Aug 4, 2010 Messages 28 Aug 24, 2010 #4 Re: Motor height on pontoon? Boaters who consider going with a higher mount can see increased speeds. Displacement hulled vessels like sailboats and workboats can benefit from a little more space between the hull and cavitation plate, but not much. Triton. Extra-long shafts are 25-inches long. 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. In lower mounting, the engine is set lower than the recommended standard. If it measures between 17 and 22, youll want to go with a long shaft motor. 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? Trimming in, trimming down, and trimming out are all terms that a beginning boater should learn. bracket. Your at your local outboard dealer shopping for a new motor and the salesman hits you with the question, "short or long shaft?". Required fields are marked *. Before we start measuring the outboard shaft length, lets get it clear about whats referring to when we talk about the outboard shaft length. To break it down a bit more for you: Short shafts are 15-inches long. Boat hulls are designed in three basic types that range from slow displacement and semi-displacement hulls to the fastest planing hulls. To do so, measure from the stern (back) of the boat to the midpoint of the hull on both sides. s = d.createElement("link"); The height is approximately six inches higher than with a propeller. This placement is not only recommended but it will give you the best performance compared to something that is too long or too short. Charles Plueddeman is Boats.com's outboard, trailer, and PWC expert. The standard shaft length for most outboard engines less than 125 horsepower is 20 inches. 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. Boat transom angles play a pivotal role in the flexibility of the boats trimming abilities. straight edge on the top of the transom to "extend" it out s.setAttribute("rel", "stylesheet"); publicId: "32bf3437d1346295e03ebcf545f9c839", 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. There is a simple test to see if your outboard motor is set at the best height. In lower mounting, the engine is set lower than the recommended standard. up to the bottom of the motor brackets, (as in #1). You can find your Mercury outboard model code on an ID plate or sticker. Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. All things considered, sticking with the industry standard is best for the beginner. Boat Transom Heights The Beginners Guide, Buying a boat can be an exciting purchase. Analytical cookies are used to understand how visitors interact with the website. This distance is very important to the performance of you boat. We also use third-party cookies that help us analyze and understand how you use this website. A: Any boat that has a 21 to 27 inch aft transom will need an extra long shaft outboard. With this in mind, how can I determine if my outboard has a short or long shaft? The cavitation plate is the horizontal surface of the lower unit immediately above the propeller. Step 2: After you get the transom height, add the radius of the propeller (check the user manual, and then technical drawing for the number) to calculate the minimum shaft length needed to make it work. This website uses cookies to improve your experience while you navigate through the website. Boaters who consider going with a higher mount can see increased speeds. It is extremely important that the boater understands the significance of the transoms height. In addition, motor totes will not harm the finish of the lower unit. The transom is the flat vertical section at the rear of the boat. mpeSelector: ".pt-mpe", h[0].appendChild(s); The first step is to determine the height of your boat's transom. You reply, "Im not sure, I think its a long". The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional". Of course, its always best to go with standard practices when choosing thebest boat engine. Mounting the motor lower on the boat transom can create excessive spray, increase case drag, reduce underwater clearance, and negatively impact faster boats. Propshaft in Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. 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. Save my name, email, and website in this browser for the next time I comment. These are vertically aligned so the boater can make adjustments. These allow the mounting of a standard length outboard behind the transom. Doing this can have adverse effects. 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. document.getElementById('cloakd53b59933f6c3f2e8b59f1b4a6d41fa5').innerHTML = ''; The clamp bracket is designed so that the engine's mounting height on the transom can be adjusted higher than standard. All rights reserved. Youll need a short shaft outboard if its 15 or less than an inch shorter. The same is true for the newest, high-powered offshore fishing boats, where triple or quadruple motor setups are becoming more and more common. The propellers will also have trouble reaching the water. This would not be a good thing. d.addEventListener("DOMContentLoaded", function (e) { However, there may be times when a boater strays away from these recommendations. This alone can outweigh the negatives when deciding to adjust the mount upwards. Many boat transoms are modified to use a different length of outboard by using a bracket. If you have a jackplate, you may have to get a bit creative in your Cavitation plates are used on the bottom components of boats to help them operate better. function gtag(){dataLayer.push(arguments);} However, your boat will have slightly more drag which will reduce your maximum speed. These cookies ensure basic functionalities and security features of the website, anonymously. 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. There are instances where a lower mount may be okay. Be sure to measure carefully and research thoroughly before diving in. The motor is what powers the boat so the two go hand-in-hand. This allows the engine to idle without the flow of the exhaust being restricted. endobj Repowering your boat is one of the most expensive upgrades you can make. disregard the downward pointing "hooks" at the front of the As you can see, the measurement is about 2 1/2". In the case of a dinghy or johnboat, this point may be the top of the transom. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. All boats are different, and the motor manufacturers produce a variety of standard lengths. 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. Now that you have a better understanding of boat transom heights its time to take out the ruler and get the perfect measurements. Having the cavitation plate too low will cause excess drag and reduced performance at high speeds. and I'll explain it better, (or point you to someone that can help. Check out the Westshore Marine & Leisure google plus page! (3) Move horizontally across the chart until you hit the graph curve. s = d.createElement("script"); These two measurements will give you the length of the shaft you need. For really big boats, the biggest and baddest six- or eight-cylinder outboards can have extra-extra long shafts up to 30 inches. Follow Westshore Marine & Leisure on Twitter! Well, raising the outboard motor can be an easy task for you. And thats usually the case since the electric outboards are designed with larger and more efficient propeller that needs longer shaft. So how to determine the outboard shaft length? 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. 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. This illustration depicts four different outboard mounting height options (courtesy Mercury Marine). The correct shaft length for your boat depends on a few factors. 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. Save my name, email, and website in this browser for the next time I comment. Always weigh the risks of making adjustments. Simply start with the engine in idle, followed by, If you decide to make some custom adjustments we have the. This provides seaworthiness and offers maximum protection from large seas. For boats equipped with a bracket, calculate the same measurement but based on the bracket and not the transom. Like Westshore Marine & Leisure on Facebook! I live for the weekends when I can go out on the water and escape the stress of life on land. 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. Step 2: Three Variables to Consider If you decide to make adjustments, please consult a marine engine dealer about the boat design. (Putting a *The Factors indicates the adjustment affected by on your boat type, the outboard working environment, and the transom distance as discussed above. Outboard motors can be fitted to a variety of boats, so manufacturers have standardized their engines to go on virtually anything. The transom is the "back wall" of your boat, the most rearward part of your hull. The faster your boat, the more critical it is to get the sizing just right. However, the shaft length for smaller boats could be long or short depending on its style, speed requirement, etc. 3 0 obj It doesnt matter if you have a fiberglass boat, bay boat, big or small boat. These are vertically aligned so the boater can make adjustments. Measuring the shaft length can be done in various ways, but the most common way is by using a tape measure. A: The short answer is Yes. The general guideline for longer shaft outboards is that the transom height should be at least 20 inches (50,8cm) above the waterline. Actual shaft length is 21.5" on those. So how to measure outboard shaft length? With the long side (22 1/2), place a carpenters square ) in opposition to the keel. To do so, take a measurement from the very top to the very bottom of the transom in the precise center. 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. A: The answer varies by boat, but here are some rules of thumb for matching a short shaft outboard to your boat. | Sitemap, The Marine Parts Warehouse Outboard Museum, OBR Powerhead / Shortblock Warranty Claim Form, Remanufactured vs. This cookie is set by GDPR Cookie Consent plugin. 5/rC,aQhsK@Q. AztH ^zv_ cT,E1K/rAB54| The amount of degrees the transom leans back from vertical is known as the transom angle. Simply start with the engine in idle, followed by trimming the motor out by one-half to full trim. These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc. Each one has a totally different effect on the boats performance. Oftentimes you will want to adjust the outboard shaft length in order to improve the boat performance such as speed. 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. Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. Buying a boat can be an exciting purchase. 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. Then adjust the motor in a higher hole with a flat head screwdriver. Using your existing control box and gauges will save you quite a bit of money in the end. https:/. Raising the motor increases the speed of the boat while decreasing the effort needed to turn the boat. The transom is the boats flat vertical part at the back. Its where the outboard motor is attached, and its also where some boat owners put the boats name. However, you will need an understanding of how the degrees will alter the boats usability. (127 mm). relation to pad would be more accurate.) (In the case of the faster No one wants to have issues with a new transom or boat repairs. priceSelector: ".price--withoutTax, span.price.price--withTax", The transom in a boat today is a place to hang your outboard motor. %PDF-1.7 It is extremely important that the boater understands the significance of the transoms height. manufacturer will recommend the outboard height according to the bracket shape and length. A big NO. Check out some hot FAQs to help you get the proper outboard shaft lengths. 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. Generally, short shaft outboards are 15 inches, long shaft outboards are 20 inches, and extra-long outboards are 25 inches. See diagram below. Measure from the top of the transom to the bottom of the hull. 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 is handy if youre shopping for second-hand outboards or looking to sell the one that came with your boat. 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. This, however, is not recommended for the beginning boater. This could also effect your travelling capabilities on the boat trailer. 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. "brackets". Pad to bottom of Gear Oil Quantity 195ml(6.6 Fl.oz.) Outboard Motor Shaft Length: How do I measure? gtag('js', new Date()); Some boats are equipped with transom-hung outboards while others have a bracket. But opting out of some of these cookies may affect your browsing experience. As a result, the issue is whether my boat need a short shaft or long shaft motor. No one wants to have issues with a new transom or boat repairs. The greater the number, the more the drive may sway (also called tuck under or negative trim). Depending on the manufacturer, size names might change. Plus, a low transom cut is an invitation for the water to flood the boat.