how to measure transom height for outboard motor

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. 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. Follow Westshore Marine & Leisure on Wordpress! straight edge from the center of the pad, but this time you're measuring While this is the case there is certain saltwater motors that are extra extra long at 30. Your goal is to measure how the outboard will sit, so start from the clamping plate and follow the centerline of the hull. Setting Height of Outboard Motor - YouTube How the outboard will sit on the back of the boat depends on how the transom is designed. of the motor off the transom How can you figure out what your transom angle is? bracket. Other uncategorized cookies are those that are being analyzed and have not been classified into a category as yet. Step 2: Three Variables to Consider It is extremely important that the boater understands the significance of the transoms height. Check out the full chart of the Mercury outboard model code and its features. As summer approaches there will be more boaters taking to the water. Safely but briskly accelerate. If it measures anywhere from 17" to around 22", then your going to want to go with a long shaft motor. document.getElementById('cloakd53b59933f6c3f2e8b59f1b4a6d41fa5').innerHTML = ''; Generally, short shaft outboards are 15 inches, long shaft outboards are 20 inches, and extra-long outboards are 25 inches. var path = 'hr' + 'ef' + '='; Take a long straight edge, (long carpenter's level or long I believe 20 to 21 inches is the optimum length for a lengthy shaft. *The Factors indicates the adjustment affected by on your boat type, the outboard working environment, and the transom distance as discussed above. The correct shaft length for your boat depends on a few factors. Among them will be first-timers or those who have recently purchased their boats. One of the factors in determining the height of the outboard is the placement of the exhaust port on the lower unit of the outboard engine. 12 Small Fishing Boat Accessories to Buy Today. Increased RPM and additional horsepower feed the need for speed. Proper Mounting Height for an Outboard - Gone Outdoors However, the motor should not be raised more than 5 inches above the standard position. endobj If it measures 15" or with in a inch of that you will need a short shaft outboard. Tilt your motor until the bullet of the gearcase is gtag('js', new Date()); Before we start measuring the outboard shaft length, lets get it clear about whats referring to when we talk about the outboard shaft length. Buying a boat can be an exciting purchase. What Is the Transom of a Boat? EXPLAINED - My Cruiser Life We also use third-party cookies that help us analyze and understand how you use this website. 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. Installing a Kicker Motor Bracket - Gone Outdoors When you measure the width of the stern, mark the center with a grease pencil. Any owner seeking the last bit of speed from an outboard-powered boat should grab a yard stick. How to Measure Transom Height For vessels with transom-mounted outboards, you can easily figure out which type of outboard you need to get. storeDisplayName: "Marine Parts Warehouse", Trimming in, trimming down, and trimming out are all terms that a beginning boater should learn. var h = d.getElementsByTagName("head"), The transom is the rear wall of the boat where the outboard engine is mounted in the middle. % Because of the increased friction, cavitation reduces efficiency. Place the bracket on the transom to the left of the main outboard or rudder. If your boat planes, pay extra attention to getting the shaft length as close to perfect as possible. This email address is being protected from spambots. There is a simple test to see if your outboard motor is set at the best height. Spark Plug 25.0nm(18.4 Ft-lb) (2.55 Kgf-m) 7. It does not store any personal data. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. manufacturer will recommend the outboard height according to the bracket shape and length. Be sure to measure carefully and research thoroughly before diving in. 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. Your at your local outboard dealer shopping for a new motor and the salesman hits you with the question, "short or long shaft?". Take your time and understand your boat and your entire transom. Simply start with the engine in idle, followed bytrimming the motor out by one-half to full trim. If you have a small boat with a 15 to 17 inch aft transom, youll most likely need a short shaft outboard. This placement is not only recommended but it will give you the best performance compared to something that is too long or too short. 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. want to measure from the transom to the flat part of this bracket, It is possible that the motor could hang low while transporting on the boat trailer causing future boat repairs. Add yours in the comment and Ill get back to you asap. There are a series of four to six holes at the top of the bracket, and the lower bolts actually fit into slots. 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). The faster your boat, the more critical it is to get the sizing just right. The cavitation plate is the horizontal surface of the lower unit immediately above the propeller. No one wants to have issues with a new transom or boat repairs. 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. Gear Oil Quantity 195ml(6.6 Fl.oz.) 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). How-To: Pick A Great Portable Outboard Motor (2023 Guide) If you have an outboard motor, the distance from one end to another will be found on the side or on a label near its bottom. You dont have to be a mathematician to determine the correct boat transom angle. 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. What Is a Transom? Where Onboard a Boat is It Located? Mounting the outboard motor in accordance with the industry standards is important. The transom is the flat vertical section at the rear of the boat. A deep Vee hull will result in a different measurement than a flatter . The height of the boat transom dictates the size of the outboard motor. As with anything, there are exceptions to the rule. What the relationship to the pontoons is, I couldn't say. There 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. Smaller 12-14 foot boats can require either a short or long shaft outboard depending on the style of the boat and the brand. While this is the case there is certain saltwater motors that are extra extra long at 30 and 35 shaft. If the height of the boat transom is off it can cause major issues. Some boats are equipped with transom-hung outboards while others have a bracket. Raising the motor increases the speed of the boat while decreasing the effort needed to turn the boat. What Is Boat Transom Height? | Gone Outdoors | Your Adventure Awaits Having the cavitation plate a bit lower than the transom is preferable to having it too high. Charles Plueddeman is Boats.com's outboard, trailer, and PWC expert. You Remember, if you use a longer outboard shaft than you need you will be increasing your draft. To sum up, there is a simple calculator of the shaft length for outboard motors: Outboard Shaft Length = Transom Height +/- Factors. Cutting the transom down is the only legal method to utilize a short shaft engine on a tall transom. How do you measure a transom on an outboard motor? 2019s List of the Best Recreational Pontoon Boats for Sale. This could also affect your travelling capabilities on the boat trailer. To do so, take a measurement from the very top to the very bottom of the transom in the precise center. Transom Outboard Engine Position - YouTube Mounting the outboard motor in accordance with the industry standards is important. These are vertically aligned so the boater can make adjustments. 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. Learn More About Your Boats Systems By Joining The Born Again Boating Academy! var interval = setInterval(function () { s.setAttribute("type", "text/javascript"); This is measured by the propeller shaft being parallel to the vessels bottom. Boat Transom Heights The Beginners Guide, Buying a boat can be an exciting purchase. Or it can have an angle degree as high as 30. Chances are the boat was designed with a specific size of outboard in mind. For really big boats, the biggest and baddest six- or eight-cylinder outboards can have extra-extra long shafts up to 30 inches. This would not be a good thing. It also cuts into speed and fuel efficiency. To achieve 35 mph with a 6 hp engine, the total weight is 135 lbs (boat motor fuel passengers). You can order an outboard in lengths ranging from 15 inches to 30 inches, depending on its power output and possible uses. Attention: Remember to measure the outboard shaft length straight up and down instead of measuring along the transom. 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. out the confusion. 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. disregard the downward pointing "hooks" at the front of the At least if its too long you can raise the motor or "build up" your transom. (We wont go into name-calling here, but the actual term for the cavitation plate is an anti-ventilation plate.) s = d.createElement("script"); #2. When measuring the transom height, you should start from the hull's bottom at the boat's center line up to the top of the transom. WHAT LENGTH OUTBOARD DO YOU REALLY NEED? - Van's Sport Center Say the 20 shaft is a long shaft length for gas engines, but it is a short shaft length for electric outboard motors. If your boat is newer and the manufacturer is still in business, you might also want to try to give them a call. 7. How high exactly do you have to raise the transom?- - Outboard Jets Ten years ago I bought my first boat. So how to determine the outboard shaft length? As summer approaches there will be more boaters taking to the water. Typical motor lengths include the following. 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. However, there may be times when a boater strays away from these recommendations. Repowering your boat is one of the most expensive upgrades you can make. <>/Metadata 127 0 R/ViewerPreferences 128 0 R>> Outboard shaft length plays a crucial role in the performance of your boat. My family and I used it to fish, ski (yes, you can ski behind a pontoon boat), and cruise the lakes near our home. The motor is what powers the boat so the two go hand-in-hand. This is the dimension you'll need when selecting a width for your outboard motor's mounting bracket. As mentioned above, the operation of the propeller relies on the transom height. With some boats I have a pretty good idea as to what length motor should be hung on them. All you need to do is measure how much to rise. ensure that your measurement is accurate. What Types of Documents Can be Sent to your Kindle Library? of the "bullet" on your lower unit. Actual shaft length is 21.5" on those. Outboard Motor Shaft Length & HP to Boat Calculating the propshaft below or above the pad. Like Westshore Marine & Leisure on Facebook! straight edge on the top of the transom to "extend" it out Always weigh the risks of making adjustments. What Kind of Fuel Does Your Marine Engine Need? However, youll notice a little increase in drag and a decrease in top-end performance. I would also recommend finding your maximum horsepower rating which is located on the yellow coast guard tag towards the back of your boat. If you decide to make adjustments, please consult a marine engine dealer about the boat design. These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc. 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). When trimming your motor, they provide you a greater bow response. e-mail :$I>M W$h"%U_yzIb?]NHg_G|r@nX eTf."SQ These cookies ensure basic functionalities and security features of the website, anonymously. Outboards designed for saltwater applications usually have longer shafts. hulls, such as Allisons, Bullets, Strokers, etc., this measurement could They keep water out of your prop and increase water pressure in the system. Knowing how this can affect the overall operation of the boat is a factor to be considered. This will be the Always weigh the risks of making adjustments. Mounting the motor lower on the boat transom can create excessive spray, increase case drag, reduce underwater clearance, and negatively impact faster boats. Is my outboard long or short shaft? function mpeInit() { The transom is the boats flat vertical part at the back. This alone can outweigh the negatives when deciding to adjust the mount upwards. ), Al Shields 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. s.setAttribute("src", script); The average transom angle is around 14 degrees. Whether you already own a boat or looking for your first watercraft we are here to service your needs. 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. %PDF-1.7 See diagram below. This, however, is not recommended for the beginning boater. 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. Next, measure from your centerline to where the outboard will be mounted on each side. Boaters who consider going with a higher mount can see increased speeds. 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. We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. This is somewhat similar to #2, in that you are again measuring with a A: Any boat that has a 21 to 27 inch aft transom will need an extra long shaft outboard. Finding the right size is a matter of looking at what youve got and taking out the measuring tape. Outboard Motor Shaft Length: How do I measure? These allow the mounting of a standard length outboard behind the transom. center of the propshaft. Engine Oil Type Genuine or Recommended 2str Engine Oil. 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. There are instances where a lower mount may be okay. Top 10 Choices for Boaters, Mercury Introduces 600HP V12 Verado Outboard Engine, The Outboard Expert: Tohatsu Propane Outboard Engine. 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. Eq*^?6R83e+j}UY.(M7k]~4g)g ~wmS{ O7t/o(W|X? Outboard Motor Shaft Length - LeeRoy's Ramblings var xmlHttp = new XMLHttpRequest(); It doesnt matter if you have a fiberglass boat, bay boat, big or small boat. These cookies will be stored in your browser only with your consent. What matters is the actual measurement in the specifications, not the name. Beginning boaters should be aware of the boats measurements. A yardstick will help you determine if your outboard engine is at the right height. Check out the Westshore Marine & Leisure google plus page! To break it down a bit more for you: Short shafts are 15-inches long. You can find your Mercury outboard model code on an ID plate or sticker. Youll need a short shaft outboard if its 15 or less than an inch shorter. Outboard Motor Shaft Length For Pontoon Boat - Survival Tech Shop The standard shaft length for most outboard engines less than 125 horsepower is 20 inches. Which Navigation Lights Does Your Boat Need? It can also improve the experience of driving a faster boat. In the second photo, we've measure down from the top of the Detwiler enableMoreInfoLink: true, It will ensure that the outboards trim will be effective, and it will save you gas too. 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. Step 2 requires the propeller's radius (check the user manual and then the technical drawing). Re: Dinghy with a long shaft motor? Thats a fairly simple list of symptoms, but if your motor is too low, youll probably notice at least one of them. The clamp bracket on the latest Mercury Four-Stoke-model outboards has five mounting bolt holes spaced .75 inches apart. The distance between the ends of a transom is measured in inches. disregard the "hooks" at the front of the boats.com is part of the Boats Group Network. C Cheaptoon Cadet Joined Aug 4, 2010 Messages 28 Aug 24, 2010 #4 Re: Motor height on pontoon? Tightening Torque for Engine. Among them will be first-timers or those who have recently purchased their boats. And thats usually the case since the electric outboards are designed with larger and more efficient propeller that needs longer shaft. How to Measure a Boat Transom - Gone Outdoors }, 100); Why wont Touch ID be under the screen in the iPhone 15 and iPhone 16? However, there may be times when a boater strays away from these recommendations. Will Charpentier is a writer who specializes in boating and maritime subjects. brackets. 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). Smaller inflatables and dinghies needshort shaft motors, whilst bigger boats require long or, in some circumstances, extreme long shaft versions. 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. One of the main concerns is causing the engine to overheat if not enough water reaches the engine to keep it cool. It also decreases the boats lift and increases the time it takes for the boat to reach plane. Thats it. But, how do you measure it? from the transom. would be more accurate.) This alone can outweigh the negatives when deciding to adjust the mount upwards. You need JavaScript enabled to view it. The clamp bracket is designed so that the engine's mounting height on the transom can be adjusted higher than standard. If the height of the boat transom is off it can cause major issues. This is simply a measurement taken from the top of the transom (top of Engine Oil Mixing Ratio Fuel 50: Engine Oil 1. The Effects of Standard, Lower and Higher Mounting. Doing this can have adverse effects. I would ask you to go back and measure the transom of your boat. 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. You must be still in the blue about that matter. Other boats that need long shafts are. Some fishing boats can handle the motor being underwater. Determining Your Boat Transom Angle The transom angle - commonly measured in degrees - is the transom's vertical inclination. (function () { This will ensure the best performance. How to Choose Between a Motor Tote and Transom Saver to Support an Place the clubs bottom on the ground as though it were going to be used to strike a golf ball. All rights reserved. up to the bottom of the motor brackets, (as in #1). 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. What's the best height for my boat motor? Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. A reversetransom that sits too high can impact the propellers of the motor and motor bracket. The point where these measurements intersect is your centerline. 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. This also means it can affect the safety of the boat. These are vertically aligned so the boater can make adjustments. 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. A: The short answer is Yes. Recommended Engine Oil 2-Stroke Outboard Motor Oil. It also includes attaching the right engine. In the case of a larger offshore boat, it may be to the top of a cutout on the . I show you how to consistently measure your prop to pad height. Kicker Motor Shaft Length - This Old Boat - Lake Ontario United - Lake As a result, the issue is whether my boat need a short shaft or long shaft motor. 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 is Transom Height? (Any measurement given as "off the transom" Later in the article is an image that shows you exactly where to measure. Some outboards have a serial number that tells you which shaft length to go for. Basically, there are three main ways to measure motor The general guideline for longer shaft outboards is that the transom height should be at least 20 inches (50,8cm) above the waterline. If youre looking for a bracket that can handle motors of up to 10/15 horsepower, go no further. The propellers will also have trouble reaching the water. Read the following to get the optimal shaft length for outboard motors! It moves an outboard up and down to optimize performance and enable a boat to venture into shallower water than it might otherwise. 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. displayPrimeOffers: true, With such an important, long-term, and expensive upgrade, its never a bad idea to double-check. I hope this helps someone out in their search for a new or newer outboard this season. You reply, "Im not sure, I think its a long". A2: Instead of changing to the short outboard shaft, you can try the Jack Plate first. Also, the boat will be more likely to hit bottom or submerge objects such as rocks or logs. relation to pad If possible for your peace of mind and not let down that magnificent purchase opportunity, place that 08 kicker at back transom and test for yourself. What is the Virtual Sundance Film Festival? clearInterval(interval); 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. Other factors to consider when determining the mounting height of an outboard are related to performance. Read the measurement on the transoms bottom. Another important measurement is the transom angle. He is also a certified marine technician and the author of a popular text on writing local history. In step 3, add another 10 cm (4") to the previous calculation in order to develop the ideal shaft length. Now that you have a better understanding of boat transom heights its time to take out the ruler and get the perfect measurements. In the case of a dinghy or johnboat, this point may be the top of the transom.