how to measure transom height for outboard motor

Some fishing boats can handle the motor being underwater. Among them will be first-timers or those who have recently purchased their boats. The outboard comes with mounting holes and brackets. These cookies track visitors across websites and collect information to provide customized ads. How do you measure a transom on an outboard motor? 4 0 obj #2. 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. With this in mind, how can I determine if my outboard has a short or long shaft? This measurement would be the inches of To achieve 35 mph with a 6 hp engine, the total weight is 135 lbs (boat motor fuel passengers). You dont have to be a mathematician to determine the correct boat transomangle. Why wont Touch ID be under the screen in the iPhone 15 and iPhone 16? When the boat transom is too low, the motor could end up underwater. Shaft lengths are available in increments of 5. window.dataLayer = window.dataLayer || []; (We wont go into name-calling here, but the actual term for the cavitation plate is an anti-ventilation plate.) Other factors to consider when determining the mounting height of an outboard are related to performance. Tightening Torque for Engine. I believe 20 to 21 inches is the optimum length for a lengthy shaft. } Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. (function () { Now that you have a better understanding of boat transom heights its time to take out the ruler and get the perfect measurements. There are instances where a lower mount may be okay. hulls, such as Allisons, Bullets, Strokers, etc., this measurement could var prefix = 'ma' + 'il' + 'to'; xmlHttp.open('POST', 'https://bes.gcp.data.bigcommerce.com/nobot'); mpeInit(); Selecting the Correct Size Outboard Shaft, What is the Best Outboard Motor for Saltwater, Diagnosing Common Outboard Motor Problems, Best Beginner Boats Everything You Need to Know. This could also affect your travelling capabilities on the boat trailer. 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). 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. 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. Gear Oil Quantity 195ml(6.6 Fl.oz.) logoColor: "original", You Repowering your boat is one of the most expensive upgrades you can make. 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. Simply start with the engine in idle, followed by, If you decide to make some custom adjustments we have the. If your boat is newer and the manufacturer is still in business, you might also want to try to give them a call. This is measured by the propeller shaft being parallel to the vessels bottom. If you are running a twin-engine setup, then measure the same distance from each clamping plate to the bottom of the hull. 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". Be sure to measure carefully and research thoroughly before diving in. Boats that use longer outboard shafts include: Owners of bass boats, RIBs, or offshore fishing boats need to get this right. Raising the motor increases the speed of the boat while decreasing the effort needed to turn the boat. It doesnt matter if you have a fiberglass boat, bay boat, big or small boat. If it measures between 17 and 22, youll want to go with a long shaft motor. This restriction includes most fishing boats and longer sailboats. Some may call it a standard length while others may call it a short or a long shaft. debugMode: false, While this is the case there is certain saltwater motors that are extra extra long at 30 and 35 shaft. s.setAttribute("type", "text/javascript"); 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. Your email address will not be published. Add the two measurements and you get 6 1/2". This email address is being protected from spambots. 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 greater the number, the more the drive may sway (also called tuck under or negative trim). It is possible that the motor could hang low while transporting on the boat trailer causing future boat repairs. relation to pad You can order an outboard in lengths ranging from 15 inches to 30 inches, depending on its power output and possible uses. The clamp bracket is designed so that the engine's mounting height on the transom can be adjusted higher than standard. The transom is the "back wall" of your boat, the most rearward part of your hull. The boat transom can be flat with zero degree angles. Here we will guide you in how to get the right boat transom height. e-mail The transom in a boat today is a place to hang your outboard motor. In the photo above, we've measured from the motor bracket to the top of 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. As mentioned above, the operation of the propeller relies on the transom height. 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. The shaft length for outboard motors has nothing to do with the water line. 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. It varies between different motors and boats. Measure from the top of the transom to the bottom of the hull. function loadScript(script) { if (PayTomorrow) { This was the height of my 225 Yamaha on my TR21 bracket forward with a straight edge to where you can then measure up But in many cases, its a little more complicated than that alone. Expectedly, when the transom angle is zero, it means it is flat. You will also risk hitting bottom or submerge objects more frequently such as rocks or logs. Whats the best height for my boat motor? If your outboard motor height. I run a 9.9 Mercury Bigfoot 20" shaft off the swim platform of my 89 Trophy 2160. Here we look at the effects of standard, lower and higher mounting. Beyond motorboats designed for large outboards, you will see outboards hanging on the sterns of everything from small canoes to large cruising sailboats. It also decreases the boats lift and increases the time it takes for the boat to reach plane. Boat transomangles play a pivotal role in the flexibility of the boats trimming abilities. var addy_textd53b59933f6c3f2e8b59f1b4a6d41fa5 = 'info' + '@' + 'vanssports' + '.' + 'com';document.getElementById('cloakd53b59933f6c3f2e8b59f1b4a6d41fa5').innerHTML += ''+addy_textd53b59933f6c3f2e8b59f1b4a6d41fa5+'<\/a>'; 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 Types of Documents Can be Sent to your Kindle Library? Pretty easy to figure out but like I said its crucial to pairing a motor with a boat. Any questions? The performance of these boats depends on quite a lot of factors, but getting the outboard length just right is an essential first step. 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. disregard the "hooks" at the front of the Small portable outboards ranging from 2 to 20 horsepower are usually sold only in short or long shaft versions. Outboard motors can be fitted to a variety of boats, so manufacturers have standardized their engines to go on virtually anything. Copyright 2017 Dealer Spike All Rights Reserved. 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? As summer approaches there will be more boaters taking to the water. With the long side (22 1/2), place a carpenters square ) in opposition to the keel. When fighting waves from the stern, a 20-inch transom is considerably safer. What's the best height for my boat motor? How can you figure out what your transom angle is? A: The answer varies by boat, but here are some rules of thumb for matching a short shaft outboard to your boat. For most boaters this is a no brainer, but for the novice or inexperienced boater it may be a tougher question. Check out some hot FAQs to help you get the proper outboard shaft lengths. You dont have to be a mathematician to determine the correct boat transom angle. Displacement hulled vessels like sailboats and workboats can benefit from a little more space between the hull and cavitation plate, but not much. *The Factors indicates the adjustment affected by on your boat type, the outboard working environment, and the transom distance as discussed above. Among them will be first-timers or those who have recently purchased their boats. on How to Measure Outboard Shaft Length: The Only Guide You Need, ePropulsion vs Torqeedo: An All-Round Comparison, 55 lb Thrust Trolling Motors: All You Need to Know Before Purchase, Spot Lock Trolling Motor: Is It Worth It & Best Options in 2022, Wiring 24V Trolling Motors: 24 Volt Wiring Diagram (with Video), LiFePO4 Battery: Why Lithium iron Phosphate Batteries Are Your Best Options in 2022, Minn Kota vs MotorGuide: Best Option in 2022. Place the point of a yardstick at the middle of the top of the boat transom. https:/. It is where the outboard is mounted, and some boat owners place the name of the boat. Long shafts are 20-inches long. This is a measurement that has been used for BassCats, I'm Triton. Take a long straight edge, (long carpenter's level or long 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. Then test the boat and adjust the height, if necessary . The same is true for the newest, high-powered offshore fishing boats, where triple or quadruple motor setups are becoming more and more common. var ptScript = "https://cdn.paytomorrow.com/js/pt-mpe.min.js"; Industry standards dictate that for short shaft engines the transom height should be 15. If it measures anywhere from 17" to around 22", then your going to want to go with a long shaft motor. center of the propshaft. 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. Actually there is no designated letter for short shaft. I show you how to consistently measure your prop to pad height. This placement is not only recommended but it will give you the best performance compared to something that is too long or too short. What are Apple Podcasts Subscriptions and Channels? With it comes a lot of responsibility and new things to learn including boat maintenance and boat basics. They operate as a planing surface, allowing your boat to climb to the top more quickly. An inch or two probably wont make a big difference, but any more than that will lead to trouble. For example, you can have the Mercury outboard shaft length by model code. MarinePartsMan.com also says that V6 bass-boat engines have a 20-inch shaft. function mpeInit() { Re: Dinghy with a long shaft motor? Picking the right shaft length is mostly a factor of the transom height or the back of the boat. Outboard shaft length plays a crucial role in the performance of your boat. All things considered, sticking with the industry standard is best for the beginner. The clamp bracket on the latest Mercury Four-Stoke-model outboards has five mounting bolt holes spaced .75 inches apart. The transom is the flat vertical section at the rear of the boat. straight edge on the top of the transom to "extend" it out These two measurements will give you the length of the shaft you need. Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. Check out the Westshore Marine & Leisure Youtube page! It moves an outboard up and down to optimize performance and enable a boat to venture into shallower water than it might otherwise. As a result, the issue is whether my boat need a short shaft or long shaft motor. The first order of business is to measure your boat for the ideal fit. To measure your outboard motor shaft length, measure from the bottom of the mounting bracket where it rests on the transom to the top of the cavitation plate, this is the horizontal surface of the lower unit immediately above the propeller. Although the longer outboard shaft length can lead to lower speed and more drag, the boat can push a heavier load. This cookie is set by GDPR Cookie Consent plugin. Charles Plueddeman is Boats.com's outboard, trailer, and PWC expert. A transom saver, which can change the spacing between the lower unit and the trailer, negates some of the support. You reply, "Im not sure, I think its a long". to where the brackets were actually resting on the transom. motor brackets The form of a boats transom varies depending on the manufacturer and model. Commonly, the transom angle ranges from 0-30 degrees, with the average transom angle set at 14 degrees. See diagram below. Offshore vessels are often equipped with a large mounting bracket so that the transom can be left at full height. Safely but briskly accelerate. It is where the outboard is mounted, and some boat owners place the name of the boat. 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? The lowest point will likely be directly under your drain plug if youve got one. Beginning boaters should be aware of the boats measurements. 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 will be the However, your boat will have slightly more drag which will reduce your maximum speed. What Kind of Fuel Does Your Marine Engine Need? See When St. Peters Basketball Games Are Today! 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. Since the ventilation plate & foil are burried under water it is obviously too low. Generally, the anti-ventilation plate on most engines is aligned with the bottom of the vessel. Ill also explain the difference between short and long shafts and how they vary by type of boat. Pad to bottom of I mean it is better to be safe than sorry, am I right? Small motors built for sailboats might come in a unique configuration with an extremely long shaft since these are mounted higher off the water. In the case of a larger offshore boat, it may be to the top of a cutout on the . The transom angle is the vertical incline of the transom and is measured in degrees. Extra-extra long shafts are 30-inches long. 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. #1: Height This, however, is not recommended for the beginning boater. C Cheaptoon Cadet Joined Aug 4, 2010 Messages 28 Aug 24, 2010 #4 Re: Motor height on pontoon? }) } }); })(document); Move the bracket as close to the center of the transom as possible while still maintaining clearance to allow the main outboard or rudder to reach its full range of motion without contacting the kicker motor. Then adjust the motor in a higher hole with a flat head screwdriver. Step 2 requires the propeller's radius (check the user manual and then the technical drawing). #3. Propshaft in ensure that your measurement is accurate. Chances are the boat was designed with a specific size of outboard in mind. You need JavaScript enabled to view it. Take your time and understand your boat and your entire transom. It doesnt matter if you have a fiberglass boat, bay boat, big or small boat. 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). ), Al Shields Beginning boaters should be aware of the boats measurements. Ten years ago I bought my first boat. up to the bottom of the motor brackets, (as in #1). Basically, there are three main ways to measure motor Increased RPM and additional horsepower feed the need for speed. The height of the boat transom dictates the size of the outboard motor. Picking the right shaft length for your outboard is an essential step in getting the best performance from your boat. On the downside, a higher mount can interfere with the boaters steering capabilities. It also cuts into speed and fuel efficiency. It can also improve the experience of driving a faster boat. At least if its too long you can raise the motor or "build up" your transom. Generally, the anti-ventilation plate on most engines is aligned with the bottom of the vessel. Some boats are equipped with transom-hung outboards while others have a bracket. 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. All you need to do is measure how much to rise. 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. Not to measure boat speed, but to gauge the mounting height of the outboard motor on the boat transom. 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. How to Measure Transom Height For vessels with transom-mounted outboards, you can easily figure out which type of outboard you need to get. If the height of the boat transom is off it can cause major issues. You also might not be able to lift the outboard out of the water entirely for storage. displayMicroOffers: false, 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. A2: Instead of changing to the short outboard shaft, you can try the Jack Plate first. One of the main concerns is causing the engine to overheat if not enough water reaches the engine to keep it cool. 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. Another important measurement is the transom angle. want to measure from the transom to the flat part of this bracket, not sure that it's still used. brackets. Place the bracket on the transom to the left of the main outboard or rudder. 3 0 obj Then open up the clamp bucket. And thats usually the case since the electric outboards are designed with larger and more efficient propeller that needs longer shaft. Learn More About Your Boats Systems By Joining The Born Again Boating Academy! Higher mounting decisions should be left to the professionals. Is my outboard long or short shaft? 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. Another important measurement is the transom angle. If you have a small boat with a 15 to 17 inch aft transom, youll most likely need a short shaft outboard. (Any measurement given as "off the transom" The boater must also consider if the boat transom support is designed to bear the weight of a higher mount.