how to measure transom height for outboard motor

There are a series of four to six holes at the top of the bracket, and the lower bolts actually fit into slots. Later in the article is an image that shows you exactly where to measure. Measure from the top of the transom to the bottom of the hull. What are Apple Podcasts Subscriptions and Channels? What the relationship to the pontoons is, I couldn't say. Engine Oil Type Genuine or Recommended 2str Engine Oil. |. Many boat transoms are modified to use a different length of outboard by using a bracket. logoColor: "original", For vee-shaped hulls, the lowest spot of the hull will come to point, while on flat-bottomed boats it will be more or less level. height (that I'm aware of); probably the most common is: If it measures anywhere from 17" to around 22", then your going to want to go with a long shaft motor. Whether your on a pontoon boat, fishing boat, or speedboat boating is always one of the best times you can have. They keep water out of your prop and increase water pressure in the system. Another important measurement is the transom angle. Safely but briskly accelerate. })(); Other uncategorized cookies are those that are being analyzed and have not been classified into a category as yet. It is very versatile as it generally . To sum up, there is a simple calculator of the shaft length for outboard motors: Outboard Shaft Length = Transom Height +/- Factors. Trimming in, trimming down, and trimming out are all terms that a beginning boater should learn. However, your boat will have slightly more drag which will reduce your maximum speed. Read the following to get the optimal shaft length for outboard motors! The boat transom can be flat with zero degree angles. displayPrimeOffers: true, 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. (Putting a The point where these measurements intersect is your centerline. Ten years ago I bought my first boat. What Types of Documents Can be Sent to your Kindle Library? The average transom angle is around 14 degrees. MPW eBay Store - Thousands of New OEM Old Stock Parts! Tilt your motor until the bullet of the gearcase is 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. s.setAttribute("href", "https://cdn.paytomorrow.com/css/pt-mpe.min.css"); However, you will need an understanding of how the degrees will alter the boats usability. Check out the Westshore Marine & Leisure Youtube page! 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. These allow the mounting of a standard length outboard behind the transom. No one wants to have issues with a new transom or boat repairs. If the propeller fails to ventilate, the motor is mounted to low. Then open up the clamp bucket. 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. 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. This provides seaworthiness and offers maximum protection from large seas. If your outboard motor height. At least if its too long you can raise the motor or "build up" your transom. mpeInit(); Spark Plug 25.0nm(18.4 Ft-lb) (2.55 Kgf-m) Recommended Engine Oil 2-Stroke Outboard Motor Oil. (Any measurement given as "off the transom" Remember, if you use a longer outboard shaft than you need you will be increasing your draft. What is Transom Height? Depending on the manufacturer, size names might change. Oftentimes you will want to adjust the outboard shaft length in order to improve the boat performance such as speed. 2 0 obj Boaters who consider going with a higher mount can see increased speeds. The faster your boat, the more critical it is to get the sizing just right. var h = d.getElementsByTagName("head"), 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. :$I>M W$h"%U_yzIb?]NHg_G|r@nX eTf."SQ To do so, take a measurement from the very top to the very bottom of the transom in the precise center. For over five years he has worked as a newspaper reporter and historic researcher. What Kind of Fuel Does Your Marine Engine Need? Boat Transom Heights The Beginners Guide, Buying a boat can be an exciting purchase. If it measures between 17 and 22, you'll want to go with a long shaft motor. PayTomorrow.mpeInit({ These cookies ensure basic functionalities and security features of the website, anonymously. If you have a question or need additional information,contact ustoday. The engine must be linked to the transom at the proper height for a propeller to best meet specific boating demands. Basically, there are three main ways to measure motor If the propeller fails to ventilate, the motor is mounted to low. Knowing how this can affect the overall operation of the boat is a factor to be considered. Most of the time, adding a hydrofoil to an outboard improves performance. Simply start with the engine in idle, followed bytrimming the motor out by one-half to full trim. <> Re: Dinghy with a long shaft motor? One of the great things about an outboard motor is how versatile it is. A2: Instead of changing to the short outboard shaft, you can try the Jack Plate first. Doing so, will put the propeller right below the boat. Industry standards dictate that for short shaft engines the transom height should be 15. Determining Your Boat Transom Angle The transom angle - commonly measured in degrees - is the transom's vertical inclination. In the case of a dinghy or johnboat, this point may be the top of the transom. 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. It is possible that the motor could hang low while transporting on the boat trailer causing future boat repairs. 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. Expectedly, when the transom angle is zero, it means it is flat. How the outboard will sit on the back of the boat depends on how the transom is designed. These are vertically aligned so the boater can make adjustments. Youll need a short shaft outboard if its 15 or less than an inch shorter. var BCData = {"csrf_token":"d7ecb6b56891bb66aee12dbc01a80162b3ed582c1acbe30f16fc9f1b2abc362f"}; 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. Among them will be first-timers or those who have recently purchased their boats. Copyright 2017 Dealer Spike All Rights Reserved. This number will likely be shorter than that for a single-engine installation since you do not necessarily measure to the point of the keel. There is a simple test to see if your outboard motor is set at the best height. Here we look at the effects of standard, lower and higher mounting. 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. window.dataLayer = window.dataLayer || []; Measure from there down to the top of the cavitation plate, also known as the anti-ventilation plate. Check the literature about your model boat online, and you may be surprised to find that the number is published for you. It also includes attaching the right engine. Commonly, the transom angle ranges from 0-30 degrees, with the average transom angle set at 14 degrees. All things considered, sticking with the industry standard is best for the beginner. As mentioned above, the operation of the propeller relies on the transom height. } Then test the boat and adjust the height, if necessary . 2019s List of the Best Recreational Pontoon Boats for Sale. I live for the weekends when I can go out on the water and escape the stress of life on land. It varies between different motors and boats. A: The short answer is Yes. actually have the propshaft above the pad.). boats.com, 1221 Brickell Avenue, 23rd Floor, Miami, FL 33131, USA. As summer approaches there will be more boaters taking to the water. On the downside, a higher mount can interfere with the boaters steering capabilities. Engine Oil Mixing Ratio Fuel 50: Engine Oil 1. 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. The brackets can add 1 inch to the overall mounting height of the outboard. Take your time and understand your boat and your entire transom. How to Measure Transom Height For vessels with transom-mounted outboards, you can easily figure out which type of outboard you need to get. If you decide to make adjustments, please consult a marine engine dealer about the boat design. 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. your motor will be higher.) Higher mounting decisions should be left to the professionals. If it measures 15" or with in a inch of that you will need a short shaft outboard. With it comes a lot of responsibility and new things to learn including boat maintenance and boat basics. xmlHttp.setRequestHeader('Content-Type', 'application/json'); Among them will be first-timers or those who have recently purchased their boats. enableMoreInfoLink: true, With a motor tote, the outboard and boat move as one, independently of the trailer, so there are no concerns about the boat shifting on the trailer, he says. 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. This is also known as the shaft length. ), Al Shields 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). This could also affect your travelling capabilities on the boat trailer. to where the brackets were actually resting on the transom. var addy_textd53b59933f6c3f2e8b59f1b4a6d41fa5 = 'info' + '@' + 'vanssports' + '.' + 'com';document.getElementById('cloakd53b59933f6c3f2e8b59f1b4a6d41fa5').innerHTML += ''+addy_textd53b59933f6c3f2e8b59f1b4a6d41fa5+'<\/a>'; Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. Follow Westshore Marine & Leisure on Twitter! 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. 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. Two years ago, I bought a Boston Whaler to fish off the coast. To do so, measure from the stern (back) of the boat to the midpoint of the hull on both sides. All boats are different, and the motor manufacturers produce a variety of standard lengths. An outboard motor can drive just about any sort of boat with proper mounting. from the transom. s.setAttribute("rel", "stylesheet"); } bracket. function loadScript(script) { What is the Virtual Sundance Film Festival? 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. Generally, the anti-ventilation plate on most engines is aligned with the bottom of the vessel. You can order an outboard in lengths ranging from 15 inches to 30 inches, depending on its power output and possible uses. It is possible that the motor could hang low while transporting on the boat trailer causing future boat repairs. Doing this can have adverse effects. This illustration depicts four different outboard mounting height options (courtesy Mercury Marine). You can find your Mercury outboard model code on an ID plate or sticker. (function (d) { 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. As with anything, there are exceptions to the rule. You'll need a short shaft outboard if it's 15 or less than an inch shorter. Picking the right shaft length for your outboard is an essential step in getting the best performance from your boat. This is measured by the propeller shaft being parallel to the vessels bottom. Cutting the transom down is the only legal method to utilize a short shaft engine on a tall transom. If the height of the boat transom is off it can cause major issues. Also, how do you determine the length of an outboard transom? Always weigh the risks of making adjustments. A: Any boat that has a 21 to 27 inch aft transom will need an extra long shaft outboard. Plus, a low transom cut is an invitation for the water to flood the boat. trimming the motor out by one-half to full trim. var h = d.getElementsByTagName("head"), Before we start measuring the outboard shaft length, lets get it clear about whats referring to when we talk about the outboard shaft length. Say the 20 shaft is a long shaft length for gas engines, but it is a short shaft length for electric outboard motors. Shaft lengths are available in increments of 5. Knowing how this can affect the overall operation of the boat is a factor to be considered. MarinePartsMan.com also says that V6 bass-boat engines have a 20-inch shaft. 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. brackets. Smaller inflatables and dinghies needshort shaft motors, whilst bigger boats require long or, in some circumstances, extreme long shaft versions. 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. If you have a jackplate, you may have to get a bit creative in your function mpeInit() { 3 0 obj 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). To achieve 35 mph with a 6 hp engine, the total weight is 135 lbs (boat motor fuel passengers). Before we get started lets see what a boat transom is and what it does. of the motor off the transom This is a measurement that has been used for BassCats, I'm The transom is the flat vertical section at the rear of the boat. This will ensure the best performance. 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. d.addEventListener("DOMContentLoaded", function (e) { On the downside, a higher mount can interfere with the boaters steering capabilities. 1 0 obj The transom is the boats flat vertical part at the back. (127 mm). #2. 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. Lubrication System Engine Oil Mixed Gasoline. When fighting waves from the stern, a 20-inch transom is considerably safer. resting on the transom if you had the motor all the way down on the boat center of the propshaft. var addyd53b59933f6c3f2e8b59f1b4a6d41fa5 = 'info' + '@'; On this type of boat, if you are in doubt, default to the longer-shafted outboard. The cavitation plate is the horizontal surface of the lower unit immediately above the propeller. disregard the "hooks" at the front of the Increased RPM and additional horsepower feed the need for speed. 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. As a result, the issue is whether my boat need a short shaft or long shaft motor. While this is the case there is certain saltwater motors that are extra extra long at 30 and 35 shaft. A deep Vee hull will result in a different measurement than a flatter . Another important measurement is the transom angle. However, youll notice a little increase in drag and a decrease in top-end performance. since 1986. 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. The cookie is used to store the user consent for the cookies in the category "Other. If you decide to make some custom adjustments we have theexperience and know-howto make it happen. 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}'); Figuring out how to measure motor height on a measuring; you may have to "extend" the flat part of the 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. Amazon has plate extensions to allow adjustments without buying a new motor: T-H Marine Jack Plate Extension. (updated Keep these numbers in mind if you ever have a need for a new outboard motor for your 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. Actual shaft length is 21.5" on those. "brackets". var ptScript = "https://cdn.paytomorrow.com/js/pt-mpe.min.js"; I would also recommend finding your maximum horsepower rating which is located on the yellow coast guard tag towards the back of your boat. The transom angle is the vertical incline of the transom and is measured in degrees. Again, make sure that you are measuring to the flat part of the brackets; The shaft length for outboard motors has nothing to do with the water line. As summer approaches there will be more boaters taking to the water. These cookies will be stored in your browser only with your consent. A1: Broadly speaking, the outboard motor shaft length for pontoon boat, bass boat, or other larger boats should be long shaft. How high exactly do you have to raise the transom?-. 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. For slower boats, its less critical to. priceSelector: ".price--withoutTax, span.price.price--withTax", %PDF-1.7 Beefier jack plates can be fitted should a boater be looking to mount an outboard with a shorter shaft than their transom demands. The how to measure the shaft length of an outboard motor is a question that many people have asked. It moves an outboard up and down to optimize performance and enable a boat to venture into shallower water than it might otherwise. While this is the case there is certain saltwater motors that are extra extra long at 30 and 35 shaft. Tightening Torque for Engine. jackplate to a point level with the top of the transom. If you are running a twin-engine setup, then measure the same distance from each clamping plate to the bottom of the hull. The first order of business is to measure your boat for the ideal fit. Step 4. In lower mounting, the engine is set lower than the recommended standard. 5/rC,aQhsK@Q. maxMicroAmount: 0.0, These are vertically aligned so the boater can make adjustments. The distance between the ends of a transom is measured in inches. We also use third-party cookies that help us analyze and understand how you use this website. C Cheaptoon Cadet Joined Aug 4, 2010 Messages 28 Aug 24, 2010 #4 Re: Motor height on pontoon? As with anything, there are exceptions to the rule. The boater must also consider if the boat transomsupport is designed to bear the weight of a higher mount. The lowest point will likely be directly under your drain plug if youve got one. You dont have to be a mathematician to determine the correct boat transom angle. You need JavaScript enabled to view it. Most transom savers can support up to a 150HP motor, which is sufficient for most regular boats. These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc. However, you will need an understanding of how the degrees will alter the boats usability. 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. If you have a question or need additional information. a Detwiler manual jackplate. The motor length corresponds to the transom height of the boat, measured from the keel to gunwale at the transom. Look at the part of your motor that would be If you have a small boat with a 15 to 17 inch aft transom, youll most likely need a short shaft outboard. With some boats I have a pretty good idea as to what length motor should be hung on them. Which Navigation Lights Does Your Boat Need? The outboard comes with mounting holes and brackets. function gtag(){dataLayer.push(arguments);} Attention: Remember to measure the outboard shaft length straight up and down instead of measuring along the transom. In the case of a larger offshore boat, it may be to the top of a cutout on the . Measure from the top of the transom to the bottom of the hull. Check out the Westshore Marine & Leisure google plus page! Or measure from the main engine prop up to the water line? clearInterval(interval); 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. (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. For most boaters this is a no brainer, but for the novice or inexperienced boater it may be a tougher question. and I'll explain it better, (or point you to someone that can help. However, there may be times when a boater strays away from these recommendations. Knowing the width, height and depth of your transom allows you to make several important decisions when selecting or purchasing a new outboard. Measure straight down to the lowest point on the hull. Triton. This is measured by the propeller shaft being parallel to the vessels bottom. mpeSelector: ".pt-mpe", Other boats that need long shafts are. If you went too long it would still work but it may lack in performance. However, there may be times when a boater strays away from these recommendations. The height of the boat transom dictates the size of the outboard motor. Higher mounting decisions should be left to the professionals. There are 2 steps to help get a relatively accurate figure. Picking the right shaft length is mostly a factor of the transom height or the back of the boat. They operate as a planing surface, allowing your boat to climb to the top more quickly. Follow Westshore Marine & Leisure on Wordpress! displayMicroOffers: false, The clamp bracket on the latest Mercury Four-Stoke-model outboards has five mounting bolt holes spaced .75 inches apart. Use the mounting bracket on the motor to know where it will sit on the boat. A reversetransom that sits too high can impact the propellers of the motor and motor bracket. I mean, who wants to purchase something as expensive as an outboard to only realize you bought the wrong one. The greater the number, the more the drive may sway (also called tuck under or negative trim). 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. xmlHttp.open('POST', 'https://bes.gcp.data.bigcommerce.com/nobot'); There This measurement was approximately 4". All rights reserved. the aluminum plate on top of the transom), to the bottom of the motor 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. out the confusion. With it comes a lot of responsibility and new things to learn includingboat maintenanceand boat basics. Beginning boaters should be aware of the boats measurements. When the boat transom is too low, the motor could end up underwater. Next, measure from your centerline to where the outboard will be mounted on each side. If you go too short your more than likely going to cavitate and loose power. Offshore vessels are often equipped with a large mounting bracket so that the transom can be left at full height. 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. Outboard motors can be fitted to a variety of boats, so manufacturers have standardized their engines to go on virtually anything. Boats with extended transoms, brackets that extend the mounting bracket for the outboard motor behind the back of the boat, can use a higher outboard height. This placement is not only recommended but it will give you the best performance compared to something that is too long or too short. Check out the full chart of the Mercury outboard model code and its features. endobj If youd like to see this in video format, skip to 0:44 in the below YouTube Video: Is it OK to put a long shaft outboard on a boat thats rated for a short shaft? 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. However, the motor should not be raised more than 5 inches above the standard position. Theyre also useful if the back of your boat has a non-standard measurement. Height Measurement: Recommended Shaft Length: 14" - 17.25" 15" Shaft (Short) 17.25" - 19.5" Varies by application 19.5" - 22.5" 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. 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. There are also specialty motor shaft lengths. A big NO. 12 Small Fishing Boat Accessories to Buy Today. 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. 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".

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