Doing this can have adverse effects. Smaller inflatables and dinghies needshort shaft motors, whilst bigger boats require long or, in some circumstances, extreme long shaft versions. How to Measure Transom Height For vessels with transom-mounted outboards, you can easily figure out which type of outboard you need to get. of the motor off the transom Owners of bass boats, RIBs, or offshore fishing boats need to get this right. Will Charpentier is a writer who specializes in boating and maritime subjects. function gtag(){dataLayer.push(arguments);} If the propeller fails to ventilate, the motor is mounted to low. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. #2. Check the literature about your model boat online, and you may be surprised to find that the number is published for you. Pad to bottom of Brackets are also handy for boats that do not have flat transoms, like canoe-stern sailboats or fan-tailed motor vessels. All you need to do is measure how much to rise. the propshaft below or above the pad. 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? will be to the flat part; if you measure to the bottom of the brackets bracket forward with a straight edge to where you can then measure up This, however, is not recommended for the beginning boater. To do so, you will want to measure at the exact center of the transom from the very top to the very bottom. Use the mounting bracket on the motor to know where it will sit on the boat. % 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. center of the propshaft. This is measured by the propeller shaft being parallel to the vessels bottom. You can use a longer shaft than recommended and your boat will work fine. function loadScript(script) { Tilt your motor until the bullet of the gearcase is clearInterval(interval); Each one has a totally different effect on the boats performance. var BCData = {"csrf_token":"d7ecb6b56891bb66aee12dbc01a80162b3ed582c1acbe30f16fc9f1b2abc362f"}; Look at the part of your motor that would be To do so, you will want to measure at the exact center of the transom from the very top to the very bottom. These are vertically aligned so the boater can make adjustments. A reversetransom that sits too high can impact the propellers of the motor and motor bracket. 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. 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. Place the bracket on the transom to the left of the main outboard or rudder. The cavitation plate is the horizontal surface of the lower unit immediately above the propeller. The center is the point where your outboard motor is (ideally) located. The pros and cons of properly . Gear Oil Quantity 195ml(6.6 Fl.oz.) Whats the best height for my boat motor? What types of boat need an extra long shaft? By clicking Accept, you consent to the use of ALL the cookies. The rearmost structural member of your boat, it not only distributes the stress of the hull generated by the bow's impact as it cleaves the water, it's the place you hang your outboard motor. Measure from there down to the top of the cavitation plate, also known as the anti-ventilation plate. Pretty easy to figure out but like I said its crucial to pairing a motor with a boat. On the downside, a higher mount can interfere with the boaters steering capabilities. 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. This could also affect your travelling capabilities on the boat trailer. Save my name, email, and website in this browser for the next time I comment. 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. 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). The height of the boat transom dictates the size of the outboard motor. 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. Follow Westshore Marine & Leisure on Wordpress! Smaller boats may use adjustable jack plates that can be changed to fit any outboard. Raising an outboard higher on the transom can reduce drag and raise top speed. A deep Vee hull will result in a different measurement than a flatter . of the "bullet" on your lower unit. hulls, such as Allisons, Bullets, Strokers, etc., this measurement could publicId: "32bf3437d1346295e03ebcf545f9c839", Thats a fairly simple list of symptoms, but if your motor is too low, youll probably notice at least one of them. straight edge on the top of the transom to "extend" it out The first step is to determine the height of your boat's transom. To make the yard stick long enough to measure the length of all the clubs, tape the ruler to the top. Actually there is no designated letter for short shaft. This alone can outweigh the negatives when deciding to adjust the mount upwards. 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). Copyright 1999-2023 Boats Group. steel ruler, etc. Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. Re: Dinghy with a long shaft motor? 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. Outboard motors can be fitted to a variety of boats, so manufacturers have standardized their engines to go on virtually anything. Charles Plueddeman is Boats.com's outboard, trailer, and PWC expert. At least if its too long you can raise the motor or "build up" your transom. All rights reserved. When mounting the engine, you want the cavitation plate to be 1 above the boat bottom for every 12 away from the transom. Copyright 2017 Dealer Spike All Rights Reserved. | Sitemap, The Marine Parts Warehouse Outboard Museum, OBR Powerhead / Shortblock Warranty Claim Form, Remanufactured vs. Or measure from the main engine prop up to the water line? Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. Say the 20 shaft is a long shaft length for gas engines, but it is a short shaft length for electric outboard motors. })(); Outboards designed for saltwater applications usually have longer shafts. As a yacht designer and boater, I prefer longer shafts. 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. It also cuts into speed and fuel efficiency. If you went too long it would still work but it may lack in performance. However, the motor should not be raised more than 5 inches above the standard position. Always weigh the risks of making adjustments. It was a 23-foot Crestliner Grand Cayman pontoon boat. These cookies will be stored in your browser only with your consent. 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. 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. Always weigh the risks of making adjustments. High powered boats usually only come in long and extra-long variants. Determining Your Boat Transom Angle The transom angle - commonly measured in degrees - is the transom's vertical inclination. 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). } Performance cookies are used to understand and analyze the key performance indexes of the website which helps in delivering a better user experience for the visitors. With it comes a lot of responsibility and new things to learn including boat maintenance and boat basics. 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. 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 4. For slower boats, its less critical to. How Transom Height Is Measured Check out the Westshore Marine & Leisure google plus page! The shaft length for outboard motors has nothing to do with the water line. This cookie is set by GDPR Cookie Consent plugin. Cavitation plates are used on the bottom components of boats to help them operate better. You These cookies ensure basic functionalities and security features of the website, anonymously. This is a measurement that has been used for BassCats, I'm Next, measure from your centerline to where the outboard will be mounted on each side. Some boats are equipped with transom-hung outboards while others have a bracket. Then adjust the motor in a higher hole with a flat head screwdriver. Is my outboard long or short shaft? gtag('js', new Date()); A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. 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. var addy_textd53b59933f6c3f2e8b59f1b4a6d41fa5 = 'info' + '@' + 'vanssports' + '.' + 'com';document.getElementById('cloakd53b59933f6c3f2e8b59f1b4a6d41fa5').innerHTML += ''+addy_textd53b59933f6c3f2e8b59f1b4a6d41fa5+'<\/a>'; With the long side (22 1/2), place a carpenters square ) in opposition to the keel. There Outboard shaft length plays a crucial role in the performance of your boat. The amount of degrees the transom leans back from vertical is known as the transom angle. 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. }, 100); Knowing the width, height and depth of your transom allows you to make several important decisions when selecting or purchasing a new outboard. 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. A reverse transom that sits too high can impact the propellers of the motor and motor bracket. The motor length corresponds to the transom height of the boat, measured from the keel to gunwale at the transom. var interval = setInterval(function () { Actual shaft length is 21.5" on those. 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. addyd53b59933f6c3f2e8b59f1b4a6d41fa5 = addyd53b59933f6c3f2e8b59f1b4a6d41fa5 + 'vanssports' + '.' + 'com'; August 9/08). Why wont Touch ID be under the screen in the iPhone 15 and iPhone 16? since 1986. Other boats that need short shafts are: A: If you have a small boat with a 18 to 21 inch aft transom, youll most likely need a long shaft outboard. If you are running a twin-engine setup, then measure the same distance from each clamping plate to the bottom of the hull. One of the great things about an outboard motor is how versatile it is. priceSelector: ".price--withoutTax, span.price.price--withTax", But opting out of some of these cookies may affect your browsing experience. You dont have to be a mathematician to determine the correct boat transom angle. But in many cases, its a little more complicated than that alone. To achieve this, the motor itself has to be attached at the correct height. The vertical distance between the interior of the clamp and the cavitation plate is the shaft length specified by the outboard manufacturer. Add yours in the comment and Ill get back to you asap. Whether your on a pontoon boat, fishing boat, or speedboat boating is always one of the best times you can have. There are instances where a lower mount may be okay. The mounting height of an outboard motor can impact the speed and handling characteristics of the boat. An inch or two probably wont make a big difference, but any more than that will lead to trouble. Wherever the outboard clamping bracket is, use this as the basis for measurement. 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". Boaters who consider going with a higher mount can see increased speeds. s.setAttribute("rel", "stylesheet"); You need JavaScript enabled to view it. A big NO. Beginning boaters should be aware of the boats measurements. Higher mounting decisions should be left to the professionals. Setting Height of Outboard Motor - YouTube 0:00 / 0:46 Setting Height of Outboard Motor nates90 71 subscribers Subscribe 83 Share 63K views 7 years ago #boatservice #outboardmotor. If the height of the boat transom is off it can cause major issues. Over time, Boating Hub has grown into a resource for boating enthusiasts around world. In addition, motor totes will not harm the finish of the lower unit. This measurement is primarily designed for single motor propulsion. Later in the article is an image that shows you exactly where to measure. (3) Move horizontally across the chart until you hit the graph curve. The cookie is used to store the user consent for the cookies in the category "Performance". Propshaft in (127 mm). It is extremely important that the boater understands the significance of the transoms height. 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. 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. Read the following to get the optimal shaft length for outboard motors! Measure from the top of the straight edge to the center of the front displayMicroOffers: false, Where Onboard a Boat is the Transom Located and More About Transom Heights A propeller operates based on the height of the transom. If you have a question or need additional information,contact ustoday. Measuring the shaft length can be done in various ways, but the most common way is by using a tape measure. The height of the boat transom dictates the size of the outboard motor. The motor is what powers the boat so the two go hand-in-hand. 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. This illustration depicts four different outboard mounting height options (courtesy Mercury Marine). In lower mounting, the engine is set lower than the recommended standard. 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. MPW eBay Store - Thousands of New OEM Old Stock Parts! Displacement hulled vessels like sailboats and workboats can benefit from a little more space between the hull and cavitation plate, but not much. Most of the time, adding a hydrofoil to an outboard improves performance. You'll need a short shaft outboard if it's 15 or less than an inch shorter. See diagram below. The Effects of Standard, Lower and Higher Mounting. 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. What is the Virtual Sundance Film Festival? 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. Mounting the motor lower on the boat transomcan createexcessive spray, increase case drag, reduce underwater clearance, and negatively impact faster boats. It is where the outboard is mounted, and some boat owners place the name of the boat. While this is the case there is certain saltwater motors that are extra extra long at 30. You must be still in the blue about that matter. (Putting a This could also effect your travelling capabilities on the boat trailer. The boater must also consider if the boat transomsupport is designed to bear the weight of a higher mount. Any questions? It is extremely important that the boater understands the significance of the transoms height. Typical motor lengths include the following. So you should just measure the height of the boat's transom from the center down to the lowest point of the hull, and compare transom height with the outboard shaft length numbers. I live for the weekends when I can go out on the water and escape the stress of life on land. 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. I show you how to consistently measure your prop to pad height. However, there may be times when a boater strays away from these recommendations. storeDisplayName: "Marine Parts Warehouse", Theyre also useful if the back of your boat has a non-standard measurement. Buying a boat can be an exciting purchase. If youre looking for a bracket that can handle motors of up to 10/15 horsepower, go no further. Mounting the outboard a little bit lower than the standard point could avoid the possible ventilation and slip on acceleration. Your goal is to measure how the outboard will sit, so start from the clamping plate and follow the centerline of the hull. Oftentimes you will want to adjust the outboard shaft length in order to improve the boat performance such as speed. s = d.createElement("script"); 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). The outboard comes with mounting holes and brackets. If you are running a slower boat, the exact location of the ventilation plate is less important. Step 3: Add another 10 cm (4'') to the previous calculation for the final ideal shaft length. Not to measure boat speed, but to gauge the mounting height of the outboard motor on the boat transom. Boaters who consider going with a higher mount can see increased speeds. var prefix = 'ma' + 'il' + 'to'; With such an important, long-term, and expensive upgrade, its never a bad idea to double-check. If the height of the boat transom is off it can cause major issues. Raising the motor increases the speed of the boat while decreasing the effort needed to turn the boat. Which Navigation Lights Does Your Boat Need? Repowering your boat is one of the most expensive upgrades you can make. Your goal is to measure how the outboard will sit, so start from the clamping plate and follow the centerline of the hull. It also decreases the boats lift and increases the time it takes for the boat to reach plane. While this is the case there is certain saltwater motors that are extra extra long at 30 and 35 shaft. You can order an outboard in lengths ranging from 15 inches to 30 inches, depending on its power output and possible uses. This would not be a good thing. <> When trimming your motor, they provide you a greater bow response. Industry standards dictate that for short shaft engines the transom height should be 15. #3. Measure the area of the transom directly where the engine will be mounted. Before we get started lets see what a boat transom is and what it does. The performance of these boats depends on quite a lot of factors, but getting the outboard length just right is an essential first step. As a result, the issue is whether my boat need a short shaft or long shaft motor. Workboats, sailboats, and displacement-hulled boats fall into this category. Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. from the transom. Amazon has plate extensions to allow adjustments without buying a new motor: T-H Marine Jack Plate Extension. <>/Metadata 127 0 R/ViewerPreferences 128 0 R>> 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. |. mpeSelector: ".pt-mpe", For really big boats, the biggest and baddest six- or eight-cylinder outboards can have extra-extra long shafts up to 30 inches. measuring; you may have to "extend" the flat part of the Spark Plug 25.0nm(18.4 Ft-lb) (2.55 Kgf-m) This placement is not only recommended but it will give you the best performance compared to something that is too long or too short. Bass boats, ski boats, or center cockpit vessels will want to double-check their measurements to get it just right. To achieve 35 mph with a 6 hp engine, the total weight is 135 lbs (boat motor fuel passengers). As mentioned above, the operation of the propeller relies on the transom height. 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}'); 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. function mpeInit() { When you measure the width of the stern, mark the center with a grease pencil. All rights reserved. On this type of boat, if you are in doubt, default to the longer-shafted outboard. The propellers will also have trouble reaching the water. Like Westshore Marine & Leisure on Facebook! Take your time and understand your boat and your entire transom. I would ask you to go back and measure the transom of your boat. Yes, if there is adequate space while the engine is tilted in the up position, a larger shaft length than what is specified may be used. All boats are different, and the motor manufacturers produce a variety of standard lengths. Height Measurement: Recommended Shaft Length: 14" - 17.25" 15" Shaft (Short) 17.25" - 19.5" Varies by application 19.5" - 22.5" If you have a question or need additional information. We also use third-party cookies that help us analyze and understand how you use this website. The average transom angle is around 14 degrees. mpeInit(); The point where these measurements intersect is your centerline. Some outboards have a serial number that tells you which shaft length to go for. document.getElementById('cloakd53b59933f6c3f2e8b59f1b4a6d41fa5').innerHTML = ''; s.setAttribute("href", "https://cdn.paytomorrow.com/css/pt-mpe.min.css"); To sum up, there is a simple calculator of the shaft length for outboard motors: Outboard Shaft Length = Transom Height +/- Factors. C Cheaptoon Cadet Joined Aug 4, 2010 Messages 28 Aug 24, 2010 #4 Re: Motor height on pontoon? 12 Small Fishing Boat Accessories to Buy Today. bracket. Check out some hot FAQs to help you get the proper outboard shaft lengths. For most boaters this is a no brainer, but for the novice or inexperienced boater it may be a tougher question. It is possible that the motor could hang low while transporting on the boat trailer causing future boat repairs. These cookies track visitors across websites and collect information to provide customized ads. Upstream Securitys Disruptive Telematics Technology, The challenges of scaling a cloud-based security system, OneStreams unified platform streamlines financial data management, OneStreams impact on the financial software market. 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. A: The short answer is Yes. 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. What are Apple Podcasts Subscriptions and Channels? %PDF-1.7 jackplate to a point level with the top of the transom. 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. 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. Triton. The standard shaft length for most outboard engines less than 125 horsepower is 20 inches. Chances are the boat was designed with a specific size of outboard in mind. Also, the boat will be more likely to hit bottom or submerge objects such as rocks or logs. Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. If the propeller fails to ventilate, the motor is mounted to low. Place the rulers end on the ground behind the club and let the club to rest on top of it. It also cuts into speed and fuel efficiency. 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. 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. Take a long straight edge, (long carpenter's level or long This alone can outweigh the negatives when deciding to adjust the mount upwards. (updated Tightening Torque for Engine. boats.com, 1221 Brickell Avenue, 23rd Floor, Miami, FL 33131, USA. (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. Picking the right shaft length for your outboard is an essential step in getting the best performance from your boat. As mentioned above, the operation of the propeller relies on the transom height. 3 0 obj 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 greater the number, the more the drive may sway (also called tuck under or negative trim). The boat transom can be flat with zero degree angles. (function (d) { Industry standards dictate that for short shaft engines the transom height should be 15. This website uses cookies to improve your experience while you navigate through the website. With this in mind, how can I determine if my outboard has a short or long shaft? Safely but briskly accelerate. The lowest point will likely be directly under your drain plug if youve got one. Other factors to consider when determining the mounting height of an outboard are related to performance. debugMode: 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. To measure the transom height, measure from the center on for transom (rear of the boat). This cookie is set by GDPR Cookie Consent plugin. PayTomorrow.mpeInit({ Before we get started lets see what a boat transom is and what it does. maxMicroAmount: 0.0, 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.
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