With such an important, long-term, and expensive upgrade, its never a bad idea to double-check. 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. Tilt your motor until the bullet of the gearcase is To achieve this, the motor itself has to be attached at the correct height. You'll need a short shaft outboard if it's 15 or less than an inch shorter. Some fishing boats can handle the motor being underwater. In step 3, add another 10 cm (4") to the previous calculation in order to develop the ideal shaft length. <>/ExtGState<>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 595.2 841.8] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> If you said something smaller than that, thats where it can get tricky. The performance of these boats depends on quite a lot of factors, but getting the outboard length just right is an essential first step. When fighting waves from the stern, a 20-inch transom is considerably safer. function gtag(){dataLayer.push(arguments);} 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. 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. We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. % Follow Westshore Marine & Leisure on Twitter! Place the rulers end on the ground behind the club and let the club to rest on top of it. Should I take the raft onto the water and measure the exact distance from the top of the transom to the water line? Simply start with the engine in idle, followed bytrimming the motor out by one-half to full trim. This is probably the worst case scenario out of the two. But, how do you measure it? Boat Transom Heights The Beginners Guide, Buying a boat can be an exciting purchase. As a dealer I don't really like hearing this because there is a chance it could go either way and you have to get it right. 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). If you have a question or need additional information. #1: Height There are also specialty motor shaft lengths. 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. C Cheaptoon Cadet Joined Aug 4, 2010 Messages 28 Aug 24, 2010 #4 Re: Motor height on pontoon? I hope this helps someone out in their search for a new or newer outboard this season. The correct shaft length for your boat depends on a few factors. At least if its too long you can raise the motor or "build up" your transom. A1: Broadly speaking, the outboard motor shaft length for pontoon boat, bass boat, or other larger boats should be long shaft. 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. 1855 Alpine Avenue NWGrand Rapids, MI 49504This email address is being protected from spambots. The cavitation plate is the horizontal surface of the lower unit immediately above the propeller. Doing this can have adverse effects. We also use third-party cookies that help us analyze and understand how you use this website. To make the yard stick long enough to measure the length of all the clubs, tape the ruler to the top. Also, the boat will be more likely to hit bottom or submerge objects such as rocks or logs. This is measured by the propeller shaft being parallel to the vessels bottom. As a yacht designer and boater, I prefer longer shafts. 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. stream loadScript(ptScript); xmlHttp.open('POST', 'https://bes.gcp.data.bigcommerce.com/nobot'); It varies between different motors and boats. You can order an outboard in lengths ranging from 15 inches to 30 inches, depending on its power output and possible uses. Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. However, there may be times when a boater strays away from these recommendations. Ill also explain the difference between short and long shafts and how they vary by type of boat. Having the cavitation plate a bit lower than the transom is preferable to having it too high. The boat transom can be flat with zero degree angles. The transom is the flat vertical section at the rear of the boat. The collapsing bubbles are loaded with extremely low-pressure water vapor, which causes damage to a variety of surfaces as they collapse. Like Westshore Marine & Leisure on Facebook! trimming the motor out by one-half to full trim. Your at your local outboard dealer shopping for a new motor and the salesman hits you with the question, "short or long shaft?". What is Transom Height? His works have appeared in regional newspapers in North Dakota and in "North Dakota Horizons" and "Cowboys and Indians" magazines. Knowing how this can affect the overall operation of the boat is a factor to be considered. former editor at Boating Magazine and contributor to many national publications The transom angle is the vertical incline of the transom and is measured in degrees. The standard installation of an outboard has the top of the transom of the boat at the same level as the bottom of the motor portion of the outboard. So how to measure outboard shaft length? A reverse transom that sits too high can impact the propellers of the motor and motor bracket. priceSelector: ".price--withoutTax, span.price.price--withTax", It also includes attaching the right engine. MPW eBay Store - Thousands of New OEM Old Stock Parts! Measure from there down to the top of the cavitation plate, also known as the anti-ventilation plate. Actual shaft length is 21.5" on those. To achieve this, the motor itself has to be attached at the correct height. Gear Oil Quantity 195ml(6.6 Fl.oz.) If you go too short your more than likely going to cavitate and loose power. I would ask you to go back and measure the transom of your boat. Sailboats use these sometimes, as well as some boaters who want to install a much smaller auxiliary motor to use in case of primary engine failure. |. Whether you already own a boat or looking for your first watercraft we are here to service your needs. It doesnt matter if you have a fiberglass boat, bay boat, big or small boat. to where the brackets were actually resting on the transom. The Effects of Standard, Lower and Higher Mounting. Oftentimes you will want to adjust the outboard shaft length in order to improve the boat performance such as speed. You also have the option to opt-out of these cookies. AztH ^zv_ cT,E1K/rAB54| of the motor off the transom Increased RPM and additional horsepower feed the need for speed. Check the literature about your model boat online, and you may be surprised to find that the number is published for you. would be more accurate.) It is very versatile as it generally . 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. The general guideline for longer shaft outboards is that the transom height should be at least 20 inches (50,8cm) above the waterline. Safely but briskly accelerate. It also decreases the boats lift and increases the time it takes for the boat to reach plane. Before we get started lets see what a boat transom is and what it does. This will be the The transom is the "back wall" of your boat, the most rearward part of your hull. As mentioned above, the operation of the propeller relies on the transom height. var path = 'hr' + 'ef' + '='; You can use a longer shaft than recommended and your boat will work fine. parallel with the straight edge. ), Al Shields Step 2: Three Variables to Consider 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. The height is approximately six inches higher than with a propeller. Generally, the anti-ventilation plate on most engines is aligned with the bottom of the vessel. Buying a boat can be an exciting purchase. Save my name, email, and website in this browser for the next time I comment. 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. Workboats, sailboats, and displacement-hulled boats fall into this category. 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. So how to determine the outboard shaft length? The transom is the flat vertical section at the rear of the boat. This website uses cookies to improve your experience while you navigate through the website. Using your existing control box and gauges will save you quite a bit of money in the end. Mounting the outboard motor in accordance with the industry standards is important. I would also recommend finding your maximum horsepower rating which is located on the yellow coast guard tag towards the back of your boat. s = d.createElement("script"); PayTomorrow.mpeInit({ You need JavaScript enabled to view it. 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. Most of the standard engined boats it takes shafts that are 15-30inches long. Small motors built for sailboats might come in a unique configuration with an extremely long shaft since these are mounted higher off the water. Eq*^?6R83e+j}UY.(M7k]~4g)g ~wmS{ O7t/o(W|X? 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). actually have the propshaft above the pad.). They keep water out of your prop and increase water pressure in the system. Each one has a totally different effect on the boats performance. Offshore vessels are often equipped with a large mounting bracket so that the transom can be left at full height. This measurement is primarily designed for single motor propulsion. If youre looking for a bracket that can handle motors of up to 10/15 horsepower, go no further. (127 mm). Thats it. You Learn More About Your Boats Systems By Joining The Born Again Boating Academy! Check out the full chart of the Mercury outboard model code and its features. Step 3: Add another 10 cm (4'') to the previous calculation for the final ideal shaft length. Get the latest updates on new products and upcoming sales, 2023 Marine Parts Warehouse Incorporated When mounting the engine, you want the cavitation plate to be 1 above the boat bottom for every 12 away from the transom. If it measures anywhere from 17" to around 22", then your going to want to go with a long shaft motor. maxMicroAmount: 0.0, 4 0 obj If you went too long it would still work but it may lack in performance. Mounting the outboard motor in accordance with the industry standards is important. To do so, you will want to measure at the exact center of the transom from the very top to the very bottom. 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. In the case of a larger offshore boat, it may be to the top of a cutout on the . Which Navigation Lights Does Your Boat Need? d.addEventListener("DOMContentLoaded", function (e) { Chances are the boat was designed with a specific size of outboard in mind. These are vertically aligned so the boater can make adjustments. 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. Or measure from the main engine prop up to the water line? Because of the increased friction, cavitation reduces efficiency. You run the risk of possibly unsafe handling if you attempt to put a long shaft engine on a transom designed for a short shaft engine. This, however, is not recommended for the beginning boater. While this is the case there is certain saltwater motors that are extra extra long at 30. Copyright 1999-2023 Boats Group. As you can see, the measurement is about 2 1/2". A: The short answer is Yes. manufacturer will recommend the outboard height according to the bracket shape and length. 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. This exhaust port should be about 1 inch above the water line when the boat is idling. The boater must also consider if the boat transomsupport is designed to bear the weight of a higher mount. A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. This is a measurement that has been used for BassCats, I'm There is a simple test to see if your outboard motor is set at the best height. Also, how do you determine the length of an outboard transom? since 1986. Many boat transoms are modified to use a different length of outboard by using a bracket. A: The answer varies by boat, but here are some rules of thumb for matching a short shaft outboard to your boat. The outboard comes with mounting holes and brackets. These are vertically aligned so the boater can make adjustments. All boats are different, and the motor manufacturers produce a variety of standard lengths. To do so, take a measurement from the very top to the very bottom of the transom in the precise center. Save my name, email, and website in this browser for the next time I comment. However, your boat will have slightly more drag which will reduce your maximum speed. This could also affect your travelling capabilities on the boat trailer. Trimming in, trimming down, and trimming out are all terms that a beginning boater should learn. Ten years ago I bought my first boat. Spark Plug 25.0nm(18.4 Ft-lb) (2.55 Kgf-m) Knowing the width, height and depth of your transom allows you to make several important decisions when selecting or purchasing a new outboard. want to measure from the transom to the flat part of this bracket, The transom is the back of the boat where the motor is hung. The outboard comes with mounting holes and brackets. 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. I run a 9.9 Mercury Bigfoot 20" shaft off the swim platform of my 89 Trophy 2160. 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. For over five years he has worked as a newspaper reporter and historic researcher. He is a Youll need a short shaft outboard if its 15 or less than an inch shorter. In addition, motor totes will not harm the finish of the lower unit. Gear case sits just below or at the hull depth due to the deep v. It is extremely important that the boater understands the significance of the transoms height. I live for the weekends when I can go out on the water and escape the stress of life on land. 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. 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. Then open up the clamp bucket. Lubrication System Engine Oil Mixed Gasoline. Step 2 requires the propeller's radius (check the user manual and then the technical drawing). The pros and cons of properly . Displacement hulled vessels like sailboats and workboats can benefit from a little more space between the hull and cavitation plate, but not much. This distance is very important to the performance of you boat. 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. measuring; you may have to "extend" the flat part of the Say the 20 shaft is a long shaft length for gas engines, but it is a short shaft length for electric outboard motors. It will ensure that the outboards trim will be effective, and it will save you gas too. boats.com is part of the Boats Group Network. Then, you can pick the right engine. Figuring out how to measure motor height on a Check out the Westshore Marine & Leisure Youtube page! 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. The cookies is used to store the user consent for the cookies in the category "Necessary". Why wont Touch ID be under the screen in the iPhone 15 and iPhone 16? 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. To do so, you will want to measure at the exact center of the transom from the very top to the very bottom. <> MarinePartsMan.com also says that V6 bass-boat engines have a 20-inch shaft. Engine Oil Type Genuine or Recommended 2str Engine Oil. You reply, "Im not sure, I think its a long". Boaters who consider going with a higher mount can see increased speeds. 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. The point where these measurements intersect is your centerline. If youre going the other way around and trying to figure out how long the shaft on your outboard is, measuring it is equally easy. a Detwiler manual jackplate. Check out some hot FAQs to help you get the proper outboard shaft lengths. 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. <> var addy_textd53b59933f6c3f2e8b59f1b4a6d41fa5 = 'info' + '@' + 'vanssports' + '.' + 'com';document.getElementById('cloakd53b59933f6c3f2e8b59f1b4a6d41fa5').innerHTML += ''+addy_textd53b59933f6c3f2e8b59f1b4a6d41fa5+'<\/a>'; He is also a certified marine technician and the author of a popular text on writing local history. The distance between the ends of a transom is measured in inches. }, 100); Among them will be first-timers or those who have recently purchased their boats. It can also improve the experience of driving a faster boat. The boater must also consider if the boat transom support is designed to bear the weight of a higher mount. <>/Metadata 127 0 R/ViewerPreferences 128 0 R>> Or it can have an angle degree as high as 30. 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. Industry transom height standards have been evolved during the last 30 years: 15 for short shaft engines, 20 for long shaft engines, and 25 for extra-long shaft engines. If you have a jackplate, you may have to get a bit creative in your Whether your on a pontoon boat, fishing boat, or speedboat boating is always one of the best times you can have. See diagram below. Some boats are equipped with transom-hung outboards while others have a bracket. A transom saver, which can change the spacing between the lower unit and the trailer, negates some of the support. x\[D~OUCO6[j](l%ay <8cylY{.L2s#]~U6A|Wj]-oo|mubqY6wbY_|!>Z8(RB:RHeTzOGO_=~t\ You dont have to be a mathematician to determine the correct boat transomangle. %PDF-1.7 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. 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. These cookies will be stored in your browser only with your consent. This cookie is set by GDPR Cookie Consent plugin. The mounting height of an outboard motor can impact the speed and handling characteristics of the boat. If your outboard motor height. (Putting a Allowing the propeller to pull water from underneath and push it out behind the boat. The center is the point where your outboard motor is (ideally) located. Top 10 Choices for Boaters, Mercury Introduces 600HP V12 Verado Outboard Engine, The Outboard Expert: Tohatsu Propane Outboard Engine. Take your time and understand your boat and your entire transom. straight edge on the top of the transom to "extend" it out This measurement was approximately 4". The average transom angle is around 14 degrees. As with anything, there are exceptions to the rule. For most boaters this is a no brainer, but for the novice or inexperienced boater it may be a tougher question. What the relationship to the pontoons is, I couldn't say. Each one has a totally different effect on the boats performance. debugMode: false, But opting out of some of these cookies may affect your browsing experience. Higher mounting decisions should be left to the professionals. resting on the transom if you had the motor all the way down on the boat #3. Copyright 2017 Dealer Spike All Rights Reserved. Higher mounting decisions should be left to the professionals. 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. Generally, the anti-ventilation plate on most engines is aligned with the bottom of the vessel. One of the main concerns is causing the engine to overheat if not enough water reaches the engine to keep it cool. This was the height of my 225 Yamaha on my TR21 How to Measure Transom Height For vessels with transom-mounted outboards, you can easily figure out which type of outboard you need to get. But in many cases, its a little more complicated than that alone. (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. Amazon has plate extensions to allow adjustments without buying a new motor: T-H Marine Jack Plate Extension. The boat transom can be flat with zero degree angles. https://www.bornagainboating.com/Get Your Born Again Boating Clothing! The faster your boat, the more critical it is to get the sizing just right. (We wont go into name-calling here, but the actual term for the cavitation plate is an anti-ventilation plate.) clearInterval(interval); Brackets are also handy for boats that do not have flat transoms, like canoe-stern sailboats or fan-tailed motor vessels. If it measures between 17 and 22, you'll want to go with a long shaft motor. 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. Raising the motor increases the speed of the boat while decreasing the effort needed to turn the boat. maxTerm: 36, s.setAttribute("rel", "stylesheet"); With this in mind, how can I determine if my outboard has a short or long shaft? Many single-engine boats mount a smaller auxiliary motor for emergency use. As summer approaches there will be more boaters taking to the water. All you need to do is measure how much to rise. The transom in a boat today is a place to hang your outboard motor. document.getElementById('cloakd53b59933f6c3f2e8b59f1b4a6d41fa5').innerHTML = ''; When the boat transom is too low, the motor could end up underwater. Smaller 12-14 foot boats can require either a short or long shaft outboard depending on the style of the boat and the brand. The transom angle is the vertical incline of the transom and is measured in degrees. and I'll explain it better, (or point you to someone that can help. My family and I used it to fish, ski (yes, you can ski behind a pontoon boat), and cruise the lakes near our home. It also cuts into speed and fuel efficiency. Simply start with the engine in idle, followed by, If you decide to make some custom adjustments we have the. This alone can outweigh the negatives when deciding to adjust the mount upwards. Measure from the top of the straight edge to the center of the front Actually there is no designated letter for short shaft. Raising an outboard higher on the transom can reduce drag and raise top speed. 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. Doing this can have adverse effects. If you are running a slower boat, the exact location of the ventilation plate is less important. Over time, Boating Hub has grown into a resource for boating enthusiasts around world. Will Charpentier is a writer who specializes in boating and maritime subjects. With a jack plate, you can mount it exactly where you want it. Any questions? Add the two measurements and you get 6 1/2". Whether you already own a boat or looking for your first watercraft we are here to service your needs. No one wants to have issues with a new transom or boat repairs. Before we get started lets see what a boat transom is and what it does. However, you will need an understanding of how the degrees will alter the boats usability. You also might not be able to lift the outboard out of the water entirely for storage. Then adjust the motor in a higher hole with a flat head screwdriver.
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