how to measure transom height for outboard motor

In the case of a larger offshore boat, it may be to the top of a cutout on the . On this type of boat, if you are in doubt, default to the longer-shafted outboard. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. With the long side (22 1/2), place a carpenters square ) in opposition to the keel. It is where the outboard is mounted, and some boat owners place the name of the boat. This exhaust port should be about 1 inch above the water line when the boat is idling. This would not be a good thing. Learn More About Your Boats Systems By Joining The Born Again Boating Academy! What the relationship to the pontoons is, I couldn't say. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. Check the literature about your model boat online, and you may be surprised to find that the number is published for you. "brackets". #1: Height Follow Westshore Marine & Leisure on Twitter! Your email address will not be published. If youre looking for a bracket that can handle motors of up to 10/15 horsepower, go no further. Should I take the raft onto the water and measure the exact distance from the top of the transom to the water line? If you have a jackplate, you may have to get a bit creative in your 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. Analytical cookies are used to understand how visitors interact with the website. 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. https:/. center of the propshaft. Later in the article is an image that shows you exactly where to measure. var addy_textd53b59933f6c3f2e8b59f1b4a6d41fa5 = 'info' + '@' + 'vanssports' + '.' + 'com';document.getElementById('cloakd53b59933f6c3f2e8b59f1b4a6d41fa5').innerHTML += ''+addy_textd53b59933f6c3f2e8b59f1b4a6d41fa5+'<\/a>'; Many boat transoms are modified to use a different length of outboard by using a bracket. This also means it can affect the safety of the boat. 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}'); These two measurements will give you the length of the shaft you need. steel ruler, etc. Look at the part of your motor that would be The transom in a boat today is a place to hang your outboard motor. It also cuts into speed and fuel efficiency. manufacturer will recommend the outboard height according to the bracket shape and length. If you go too short your more than likely going to cavitate and loose power. This measurement would be the inches of Place the bracket on the transom to the left of the main outboard or rudder. Many single-engine boats mount a smaller auxiliary motor for emergency use. The greater the number, the more the drive may sway (also called tuck under or negative trim). Other uncategorized cookies are those that are being analyzed and have not been classified into a category as yet. 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. However, youll notice a little increase in drag and a decrease in top-end performance. These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc. Measure from the top of the straight edge to the center of the front If the height of the boat transom is off it can cause major issues. Safely but briskly accelerate. 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. Tightening Torque for Engine. 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). If you are running a slower boat, the exact location of the ventilation plate is less important. The boater must also consider if the boat transom support is designed to bear the weight of a higher mount. gtag('js', new Date()); Again, make sure that you are measuring to the flat part of the brackets; 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. Repowering your boat is one of the most expensive upgrades you can make. stream Simply start with the engine in idle, followed bytrimming the motor out by one-half to full trim. Knowing how this can affect the overall operation of the boat is a factor to be considered. Also, the boat will be more likely to hit bottom or submerge objects such as rocks or logs. If you decide to make adjustments, please consult a marine engine dealer about the boatdesign. But in many cases, its a little more complicated than that alone. Safely but briskly accelerate. What is the Virtual Sundance Film Festival? When the boattransom is too low, the motor could end up underwater. brackets. Cavitation plates are used on the bottom components of boats to help them operate better. to where the brackets were actually resting on the transom. var xmlHttp = new XMLHttpRequest(); Recommended Engine Oil 2-Stroke Outboard Motor Oil. This will keep the prop in the water when the boat pitches in waves, or hobby-horses. 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. logoColor: "original", In the past, though, it housed the officers and captain of 17th, 18th and 19th century sailing ships. The propellers will also have trouble reaching the water. 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 propellers will also have trouble reaching the water. You dont have to be a mathematician to determine the correct boat transomangle. I show you how to consistently measure your prop to pad height. resting on the transom if you had the motor all the way down on the boat Attention: Remember to measure the outboard shaft length straight up and down instead of measuring along the transom. 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. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. This provides seaworthiness and offers maximum protection from large seas. With some boats I have a pretty good idea as to what length motor should be hung on them. This was the height of my 225 Yamaha on my TR21 4 0 obj Using your existing control box and gauges will save you quite a bit of money in the end. A: The short answer is Yes. Figuring out how to measure motor height on a Take the center measurement from the top to the bottom of the hull. s.setAttribute("type", "text/javascript"); Rebuilt - What You Need to Know, Lower Unit and Sterndrive Break-In Instructions. 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. 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. The point where these measurements intersect is your centerline. Place the clubs bottom on the ground as though it were going to be used to strike a golf ball. 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. 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". How do you measure a transom on an outboard motor? It doesnt matter if you have a fiberglass boat, bay boat, big or small boat. In lower mounting, the engine is set lower than the recommended standard. 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. trimming the motor out by one-half to full trim. Necessary cookies are absolutely essential for the website to function properly. Copyright 2017 Dealer Spike All Rights Reserved. To make the yard stick long enough to measure the length of all the clubs, tape the ruler to the top. For most boaters this is a no brainer, but for the novice or inexperienced boater it may be a tougher question. Most of the standard engined boats it takes shafts that are 15-30inches long. It also cuts into speed and fuel efficiency. There is a simple test to see if your outboard motor is set at the best height. All you need to do is measure how much to rise. So how to determine the outboard shaft length? Take a long straight edge, (long carpenter's level or long The transom angle is the vertical incline of the transom and is measured in degrees. Actual shaft length is 21.5" on those. 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. So how to measure outboard shaft length? Eq*^?6R83e+j}UY.(M7k]~4g)g ~wmS{ O7t/o(W|X? Like Westshore Marine & Leisure on Facebook! Will Charpentier is a writer who specializes in boating and maritime subjects. Measure from the top of the transom to the bottom of the hull. 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. Whats the best height for my boat motor? 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. (3) Move horizontally across the chart until you hit the graph curve. Problems with getting the ventilation plate too low include slower hole-shot and lower top-end speeds. If you have a question or need additional information. If you have a short shaft motor, the distance between the top of the transom and the bottom of the boat should be between 15 and 16 inches. If it measures anywhere from 17" to around 22", then your going to want to go with a long shaft motor. publicId: "32bf3437d1346295e03ebcf545f9c839", Wherever the outboard clamping bracket is, use this as the basis for measurement. Knowing the width, height and depth of your transom allows you to make several important decisions when selecting or purchasing a new outboard. If you said something smaller than that, thats where it can get tricky. I live for the weekends when I can go out on the water and escape the stress of life on land. However, there may be times when a boater strays away from these recommendations. jackplate to a point level with the top of the transom. However, your boat will have slightly more drag which will reduce your maximum speed. 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. Use the mounting bracket on the motor to know where it will sit on the boat. 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. xmlHttp.open('POST', 'https://bes.gcp.data.bigcommerce.com/nobot'); Finding the right size is a matter of looking at what youve got and taking out the measuring tape. You need JavaScript enabled to view it. It also decreases the boats lift and increases the time it takes for the boat to reach plane. Determining Your Boat Transom Angle The transom angle - commonly measured in degrees - is the transom's vertical inclination. 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. (Putting a 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). var interval = setInterval(function () { What Kind of Fuel Does Your Marine Engine Need? You can find your Mercury outboard model code on an ID plate or sticker. 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. It varies between different motors and boats. since 1986. Amazon has plate extensions to allow adjustments without buying a new motor: T-H Marine Jack Plate Extension. The first order of business is to measure your boat for the ideal fit. var h = d.getElementsByTagName("head"), As mentioned above, the operation of the propeller relies on the transom height. 5/rC,aQhsK@Q. Place the rulers end on the ground behind the club and let the club to rest on top of it. The mounting height of an outboard motor can impact the speed and handling characteristics of the boat. Happy boating! Beyond motorboats designed for large outboards, you will see outboards hanging on the sterns of everything from small canoes to large cruising sailboats. Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. 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. The form of a boats transom varies depending on the manufacturer and model. Once you know what will fit on your hull, you can fine-tune your choice based on the performance youre looking for and how you use the boat. This cookie is set by GDPR Cookie Consent plugin. Propshaft in s = d.createElement("link"); There are instances where a lower mount may be okay. function mpeInit() { 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. Check out the Westshore Marine & Leisure Youtube page! mpeSelector: ".pt-mpe", If you have a question or need additional information,contact ustoday. endobj The amount of degrees the transom leans back from vertical is known as the transom angle. Depending on the manufacturer, size names might change. The standard shaft length for most outboard engines less than 125 horsepower is 20 inches. Having the cavitation plate too low will cause excess drag and reduced performance at high speeds. If your boats transom height is 15-16, a short shaft engine is required, and if it is 20-21, a long shaft engine is required. Which Navigation Lights Does Your Boat Need? Triton. <>/Metadata 127 0 R/ViewerPreferences 128 0 R>> See When St. Peters Basketball Games Are Today! 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. 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. If you have a small boat with a 15 to 17 inch aft transom, youll most likely need a short shaft outboard. To achieve this, the motor itself has to be attached at the correct height. <>/ExtGState<>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 595.2 841.8] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> No one wants to have issues with a new transom or boat repairs. Make sure that you are measuring straight up, at a 90 degree angle to Mounting the outboard motor in accordance with the industry standards is important. The motor is what powers the boat so the two go hand-in-hand. What matters is the actual measurement in the specifications, not the name. While this is the case there is certain saltwater motors that are extra extra long at 30. Most of the time, adding a hydrofoil to an outboard improves performance. Displacement hulled vessels like sailboats and workboats can benefit from a little more space between the hull and cavitation plate, but not much. enableMoreInfoLink: true, In addition, motor totes will not harm the finish of the lower unit. The transom is the flat vertical section at the rear of the boat. These are vertically aligned so the boater can make adjustments. x\[D~OUCO6[j](l%ay <8cylY{.L2s#]~U6A|Wj]-oo|mubqY6wbY_|!>Z8(RB:RHeTzOGO_=~t\ The transom is the rear wall of the boat where the outboard engine is mounted in the middle. 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. 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. s.setAttribute("href", "https://cdn.paytomorrow.com/css/pt-mpe.min.css"); AztH ^zv_ cT,E1K/rAB54| Read the measurement on the transoms bottom. boats.com, 1221 Brickell Avenue, 23rd Floor, Miami, FL 33131, USA. When fighting waves from the stern, a 20-inch transom is considerably safer. Picking the right shaft length is mostly a factor of the transom height or the back of the boat. Or measure from the main engine prop up to the water line? For boats equipped with a bracket, calculate the same measurement but based on the bracket and not the transom. Spark Plug 25.0nm(18.4 Ft-lb) (2.55 Kgf-m) On the downside, a higher mount can interfere with the boaters steering capabilities. 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. 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. Outboards designed for saltwater applications usually have longer shafts. Tilt your motor until the bullet of the gearcase is This email address is being protected from spambots. out the confusion. Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. So if you are measuring the outboard shaft length for the powerboat, planing boat, or any boat for which the speed is the priority, take the outboard shaft length 1 to 1.5 (depending on your boat types) shorter than standard would be better. Measure from the top of the transom to the bottom of the hull. Not to measure boat speed, but to gauge the mounting height of the outboard motor on the boat transom. The height of the boat transom dictates the size of the outboard motor. } Increased RPM and additional horsepower feed the need for speed. var ptScript = "https://cdn.paytomorrow.com/js/pt-mpe.min.js"; It is extremely important that the boater understands the significance of the transoms height. Mounting the outboard motor in accordance with the industry standards is important. This website uses cookies to improve your experience while you navigate through the website. Its important to note that manufacturers call their models different things. For really big boats, the biggest and baddest six- or eight-cylinder outboards can have extra-extra long shafts up to 30 inches. Ten years ago I bought my first boat. Engine Oil Mixing Ratio Fuel 50: Engine Oil 1. This distance is very important to the performance of you boat. While this is the case there is certain saltwater motors that are extra extra long at 30 and 35 shaft. If the propeller fails to ventilate, the motor is mounted to low. 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. (function (d) { The boat transom can be flat with zero degree angles. 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. Anything bigger than that your obviously going to need an extra long shaft. Required fields are marked *. Some boats are equipped with transom-hung outboards while others have a bracket. Where Onboard a Boat is the Transom Located and More About Transom Heights A propeller operates based on the height of the transom. Among them will be first-timers or those who have recently purchased their boats. You'll need a short shaft outboard if it's 15 or less than an inch shorter. On the downside, a higher mount can interfere with the boaters steering capabilities. What are Apple Podcasts Subscriptions and Channels? MPW eBay Store - Thousands of New OEM Old Stock Parts! Industry standards dictate that for short shaft engines the transom height should be 15. They operate as a planing surface, allowing your boat to climb to the top more quickly. This is simply a measurement taken from the top of the transom (top of And thats usually the case since the electric outboards are designed with larger and more efficient propeller that needs longer shaft. However, you will need an understanding of how the degrees will alter the boats usability. This cookie is set by GDPR Cookie Consent plugin. Measure straight down to the lowest point on the hull. The shaft length for outboard motors has nothing to do with the water line. 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. 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. Well, raising the outboard motor can be an easy task for you. We also use third-party cookies that help us analyze and understand how you use this website. Take your time and understand your boat and your entire transom. Boat transomangles play a pivotal role in the flexibility of the boats trimming abilities. There are a series of four to six holes at the top of the bracket, and the lower bolts actually fit into slots. For slower boats, its less critical to. With it comes a lot of responsibility and new things to learn includingboat maintenanceand boat basics. The cookie is used to store the user consent for the cookies in the category "Analytics". A reversetransom that sits too high can impact the propellers of the motor and motor bracket. var prefix = 'ma' + 'il' + 'to'; 3 0 obj There 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. You need JavaScript enabled to view it. These cookies will be stored in your browser only with your consent. In the photo above, we've measured from the motor bracket to the top of If you have already measured you transom tip to bottom to be 20", then if you place aux sdieways to central engine your available transom height will be probably 1"-1.5" " higher and work perfecty. I mean it is better to be safe than sorry, am I right? You must be still in the blue about that matter. You also have the option to opt-out of these cookies. Measure the area of the transom directly where the engine will be mounted. Pad to bottom of Engine Oil Type Genuine or Recommended 2str Engine Oil. If it measures 15" or with in a inch of that you will need a short 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.