I believe 20 to 21 inches is the optimum length for a lengthy shaft. As you can see, the measurement is about 2 1/2". The pressure behind your hand dropped as you slid your hand back and forth through the water. To achieve 35 mph with a 6 hp engine, the total weight is 135 lbs (boat motor fuel passengers). Check out the Westshore Marine & Leisure Youtube page! Most transom savers can support up to a 150HP motor, which is sufficient for most regular boats. The propellers will also have trouble reaching the water. This alone can outweigh the negatives when deciding to adjust the mount upwards. Whether your on a pontoon boat, fishing boat, or speedboat boating is always one of the best times you can have. Oftentimes you will want to adjust the outboard shaft length in order to improve the boat performance such as speed. 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. If the propeller fails to ventilate, the motor is mounted to low. (Any measurement given as "off the transom" document.getElementById('cloakd53b59933f6c3f2e8b59f1b4a6d41fa5').innerHTML = ''; Most of the time, adding a hydrofoil to an outboard improves performance. However, your boat will have slightly more drag which will reduce your maximum speed. Eq*^?6R83e+j}UY.(M7k]~4g)g ~wmS{ O7t/o(W|X? Outboard Motor Shaft Length: How do I measure? Where Onboard a Boat is the Transom Located and More About Transom Heights A propeller operates based on the height of the transom. endobj With it comes a lot of responsibility and new things to learn includingboat maintenanceand boat basics. The transom is the rear wall of the boat where the outboard engine is mounted in the middle. resting on the transom if you had the motor all the way down on the boat minAmount: 300.0, 4 0 obj If you are looking to repower, they may be able to offer some sage advice. Owners of bass boats, RIBs, or offshore fishing boats need to get this right. You also have the option to opt-out of these cookies. Take the center measurement from the top to the bottom of the hull. If you are running a twin-engine setup, then measure the same distance from each clamping plate to the bottom of the hull. If it measures 15" or with in a inch of that you will need a short shaft outboard. The transom is the flat vertical section at the rear of the boat. Beyond motorboats designed for large outboards, you will see outboards hanging on the sterns of everything from small canoes to large cruising sailboats. 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. In lower mounting, the engine is set lower than the recommended standard. An inch or two probably wont make a big difference, but any more than that will lead to trouble. Displacement hulled vessels like sailboats and workboats can benefit from a little more space between the hull and cavitation plate, but not much. (Putting a C Cheaptoon Cadet Joined Aug 4, 2010 Messages 28 Aug 24, 2010 #4 Re: Motor height on pontoon? This, however, is not recommended for the beginning boater. 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. %PDF-1.7 To do so, measure from the stern (back) of the boat to the midpoint of the hull on both sides. But opting out of some of these cookies may affect your browsing experience. 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. 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). With this in mind, how can I determine if my outboard has a short or 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}'); Beginning boaters should be aware of the boats measurements. Industry standards dictate that for short shaft engines the transom height should be 15. e-mail Simply start with the engine in idle, followed by trimming the motor out by one-half to full trim. 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. With it comes a lot of responsibility and new things to learn including boat maintenance and boat basics. The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. var h = d.getElementsByTagName("head"), Generally, the anti-ventilation plate on most engines is aligned with the bottom of the vessel. Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. Also, the boat will be more likely to hit bottom or submerge objects such as rocks or logs. s.setAttribute("type", "text/javascript"); Buying a boat can be an exciting purchase. The average transom angle is around 14 degrees. The correct shaft length for your boat depends on a few factors. function gtag(){dataLayer.push(arguments);} If you decide to make adjustments, please consult a marine engine dealer about the boat design. If the height of the boat transom is off it can cause major issues. Here we look at the effects of standard, lower and higher mounting. Say the 20 shaft is a long shaft length for gas engines, but it is a short shaft length for electric outboard motors. The brackets can add 1 inch to the overall mounting height of the outboard. To sum up, there is a simple calculator of the shaft length for outboard motors: Outboard Shaft Length = Transom Height +/- Factors. <>/Metadata 127 0 R/ViewerPreferences 128 0 R>> I also love helping others, which is why I created this website. if (PayTomorrow) { center of the propshaft. The amount of degrees the transom leans back from vertical is known as the transom angle. The anti-cavitation plate above the prop needs to be within an inch of the bottom of the transom, therefore, the prop should be well below the transom. Step 2: Three Variables to Consider Generally, short shaft outboards are 15 inches, long shaft outboards are 20 inches, and extra-long outboards are 25 inches. The general guideline for longer shaft outboards is that the transom height should be at least 20 inches (50,8cm) above the waterline. former editor at Boating Magazine and contributor to many national publications One of the great things about an outboard motor is how versatile it is. The motor is what powers the boat so the two go hand-in-hand. What are Apple Podcasts Subscriptions and Channels? 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. maxAmount: 6500.0, (We wont go into name-calling here, but the actual term for the cavitation plate is an anti-ventilation plate.) Boat transom angles play a pivotal role in the flexibility of the boats trimming abilities. If it measures anywhere from 17" to around 22", then your going to want to go with a long shaft motor. bracket. Boats that use longer outboard shafts include: The motor length corresponds to the transom height of the boat, measured from the keel to gunwale at the transom. The point where these measurements intersect is your centerline. Brackets are also handy for boats that do not have flat transoms, like canoe-stern sailboats or fan-tailed motor vessels. Shaft lengths are available in increments of 5. Trimming in, trimming down, and trimming out are all terms that a beginning boater should learn. https://www.bornagainboating.com/Get Your Born Again Boating Clothing! I mean it is better to be safe than sorry, am I right? 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. If your boats transom height is 15-16, a short shaft engine is required, and if it is 20-21, a long shaft engine is required. Check out some hot FAQs to help you get the proper outboard shaft lengths. Of course, its always best to go with standard practices when choosing thebest boat engine. Mounting the motor lower on the boat transomcan createexcessive spray, increase case drag, reduce underwater clearance, and negatively impact faster boats. 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. This provides seaworthiness and offers maximum protection from large seas. When trimming your motor, they provide you a greater bow response. I hope this helps someone out in their search for a new or newer outboard this season. These cookies track visitors across websites and collect information to provide customized ads. It is extremely important that the boater understands the significance of the transoms height. Be sure to measure carefully and research thoroughly before diving in. Extra-long shafts are 25-inches long. 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. 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. Step 4. 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. This will keep the prop in the water when the boat pitches in waves, or hobby-horses. xmlHttp.setRequestHeader('Content-Type', 'application/json'); To achieve this, the motor itself has to be attached at the correct height. 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. All rights reserved. Add the two measurements and you get 6 1/2". He is a Beginning boaters should be aware of the boats measurements. 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. It will ensure that the outboards trim will be effective, and it will save you gas too. disregard the "hooks" at the front of the 2019s List of the Best Recreational Pontoon Boats for Sale. Safely but briskly accelerate. A: The short answer is Yes. Place the rulers end on the ground behind the club and let the club to rest on top of it. It is extremely important that the boater understands the significance of the transoms height. If you decide to make some custom adjustments we have theexperience and know-howto make it happen. 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. A reversetransom that sits too high can impact the propellers of the motor and motor bracket. The greater the number, the more the drive may sway (also called tuck under or negative trim). relation to pad It is possible that the motor could hang low while transporting on the boat trailer causing future boat repairs. 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. They keep water out of your prop and increase water pressure in the system. boats.com is part of the Boats Group Network. trimming the motor out by one-half to full trim. If it measures between 17 and 22, youll want to go with a long shaft motor. The height of the boat transom dictates the size of the outboard motor. Knowing the width, height and depth of your transom allows you to make several important decisions when selecting or purchasing a new outboard. Extra-extra long shafts are 30-inches long. While this is the case there is certain saltwater motors that are extra extra long at 30 and 35 shaft. 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. Long shafts are 20-inches long. My family and I used it to fish, ski (yes, you can ski behind a pontoon boat), and cruise the lakes near our home. 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. displayMicroOffers: false, This illustration depicts four different outboard mounting height options (courtesy Mercury Marine). endobj Wherever the outboard clamping bracket is, use this as the basis for measurement. Analytical cookies are used to understand how visitors interact with the website. hulls, such as Allisons, Bullets, Strokers, etc., this measurement could For boats equipped with a bracket, calculate the same measurement but based on the bracket and not the transom. Should I take the raft onto the water and measure the exact distance from the top of the transom to the water line? var prefix = 'ma' + 'il' + 'to'; function mpeInit() { 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. Measure the area of the transom directly where the engine will be mounted. Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. Your goal is to measure how the outboard will sit, so start from the clamping plate and follow the centerline of the hull. displayPrimeOffers: true, For really big boats, the biggest and baddest six- or eight-cylinder outboards can have extra-extra long shafts up to 30 inches. ), and place it on the bottom of the pad in the center. }, 100); The cookies is used to store the user consent for the cookies in the category "Necessary". The height of the boat transom dictates the size of the outboard motor. bassboat can be a bit confusing at times; hopefully this will help sort Using your existing control box and gauges will save you quite a bit of money in the end. It does not store any personal data. Mounting the motor lower on the boat transom can create excessive spray, increase case drag, reduce underwater clearance, and negatively impact faster boats. s.setAttribute("rel", "stylesheet"); Buying a boat can be an exciting purchase. Other factors to consider when determining the mounting height of an outboard are related to performance. addyd53b59933f6c3f2e8b59f1b4a6d41fa5 = addyd53b59933f6c3f2e8b59f1b4a6d41fa5 + 'vanssports' + '.' + 'com'; This cookie is set by GDPR Cookie Consent plugin. Gear Oil Quantity 195ml(6.6 Fl.oz.) You may wonder how deep your prop should be in the water. When the boattransom is too low, the motor could end up underwater. 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. It can also improve the experience of driving a faster boat. Now that you have a better understanding of boat transom heights its time to take out the ruler and get the perfect measurements. You will also risk hitting bottom or submerge objects more frequently such as rocks or logs. It doesnt matter if you have a fiberglass boat, bay boat, big or small boat. Doing this can have adverse effects. Two years ago, I bought a Boston Whaler to fish off the coast. s.setAttribute("href", "https://cdn.paytomorrow.com/css/pt-mpe.min.css"); (function () { In the case of a larger offshore boat, it may be to the top of a cutout on the . enableMoreInfoLink: true, You can find your Mercury outboard model code on an ID plate or sticker. % loadScript(ptScript); 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. Your email address will not be published. Check the literature about your model boat online, and you may be surprised to find that the number is published for you. 7. Expectedly, when the transom angle is zero, it means it is flat. The transom in a boat today is a place to hang your outboard motor. A big NO. https:/. 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. The average transom angle is around 14 degrees. This website uses cookies to improve your experience while you navigate through the website. Raising the motor increases the speed of the boat while decreasing the effort needed to turn the boat. While this is the case there is certain saltwater motors that are extra extra long at 30. See diagram below. This was the height of my 225 Yamaha on my TR21 The outboard comes with mounting holes and brackets. 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. Since the ventilation plate & foil are burried under water it is obviously too low. One of the main concerns is causing the engine to overheat if not enough water reaches the engine to keep it cool. Propshaft in 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). A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. This exhaust port should be about 1 inch above the water line when the boat is idling. 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. What matters is the actual measurement in the specifications, not the name. Beefier jack plates can be fitted should a boater be looking to mount an outboard with a shorter shaft than their transom demands. As with anything, there are exceptions to the rule. I would also recommend finding your maximum horsepower rating which is located on the yellow coast guard tag towards the back of your boat. This could also effect your travelling capabilities on the boat trailer. The transom angle is the vertical incline of the transom and is measured in degrees. The faster your boat, the more critical it is to get the sizing just right. })(); "brackets". 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: The answer varies by boat, but here are some rules of thumb for matching a short shaft outboard to your boat. Look at the part of your motor that would be This cookie is set by GDPR Cookie Consent plugin. Boat transomangles play a pivotal role in the flexibility of the boats trimming abilities. So in hopes that this will help out some new boaters this spring, here's a little rundown on outboard shaft sizes and how to figure out which one you actually need. All rights reserved. Also, how do you determine the length of an outboard transom? } 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. Offshore vessels are often equipped with a large mounting bracket so that the transom can be left at full height. Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. With it comes a lot of responsibility and new things to learn including, Why your boat transom needs to be the right height, The pros and cons of properly mounting the outboard motor to the transom, Standard mounting is always best for the beginner, Of course, its always best to go with standard practices when choosing the, Lower mounting is not for the beginning boater, Mounting the motor lower on the boat transom, There is a simple test to see if your outboard motor is set at the best height. All you need to do is measure how much to rise. A2: Instead of changing to the short outboard shaft, you can try the Jack Plate first. This is probably the worst case scenario out of the two. ensure that your measurement is accurate. Theyre also useful if the back of your boat has a non-standard measurement. h[0].appendChild(s); Increased RPM and additional horsepower feed the need for speed. Re: Dinghy with a long shaft motor? However, with the outboard shaft length too short, meaning the prop is too close to the surface, the engine is likely to ventilate and therefore slip on acceleration or lose power. out the confusion. Add yours in the comment and Ill get back to you asap. Measure from the top of the transom to the bottom of the hull. What the relationship to the pontoons is, I couldn't say. The transom is the flat vertical section at the rear of the boat. As a result, the issue is whether my boat need a short shaft or long shaft motor. The center is the point where your outboard motor is (ideally) located. 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. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. The first step is to determine the height of your boat's transom. As mentioned above, the operation of the propeller relies on the transom height. parallel with the straight edge. var ptScript = "https://cdn.paytomorrow.com/js/pt-mpe.min.js"; 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. 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 transom is the "back wall" of your boat, the most rearward part of your hull. Gear case sits just below or at the hull depth due to the deep v. Place the bracket on the transom to the left of the main outboard or rudder. var interval = setInterval(function () { (3) Move horizontally across the chart until you hit the graph curve. s = d.createElement("script"); Simply start with the engine in idle, followed by, If you decide to make some custom adjustments we have the. 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. 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 Heights The Beginners Guide, Buying a boat can be an exciting purchase. mpeInit(); To make the yard stick long enough to measure the length of all the clubs, tape the ruler to the top. Actual shaft length is 21.5" on those. One of the main concerns is causing the engine to overheat if not enough water reaches the engine to keep it cool. On this type of boat, if you are in doubt, default to the longer-shafted outboard. This measurement would be the inches of of the motor off the transom This also means it can affect the safety of the boat. The clamp bracket is designed so that the engine's mounting height on the transom can be adjusted higher than standard. As with anything, there are exceptions to the rule. Recommended Engine Oil 2-Stroke Outboard Motor Oil. d.addEventListener("DOMContentLoaded", function (e) { Bass boats, ski boats, or center cockpit vessels will want to double-check their measurements to get it just right. However, you will need an understanding of how the degrees will alter the boats usability. Or it can have an angle degree as high as 30. 3 0 obj And thats usually the case since the electric outboards are designed with larger and more efficient propeller that needs longer shaft. bracket forward with a straight edge to where you can then measure up Actually there is no designated letter for short shaft. Trimming in, trimming down, and trimming out are all terms that a beginning boater should learn.