how to measure transom height for outboard motor how to measure transom height for outboard motor

Outboard shaft length plays a crucial role in the performance of your boat. Measure from the top of the transom to the bottom of the hull. To measure the transom height, measure from the center on for transom (rear of the boat). Boat transomangles play a pivotal role in the flexibility of the boats trimming abilities. If youre looking for a bracket that can handle motors of up to 10/15 horsepower, go no further. Before we get started lets see what a boat transom is and what it does. If you have a question or need additional information,contact ustoday. If it measures anywhere from 17" to around 22", then your going to want to go with a long shaft motor. It can also improve the experience of driving a faster boat. You 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. Step 2 requires the propeller's radius (check the user manual and then the technical drawing). These cookies ensure basic functionalities and security features of the website, anonymously. } var path = 'hr' + 'ef' + '='; Raising an outboard higher on the transom can reduce drag and raise top speed. This cookie is set by GDPR Cookie Consent plugin. Tilt your motor until the bullet of the gearcase is If so, send me an All rights reserved. If the height of the boat transom is off it can cause major issues. 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. In the second photo, we've measure down from the top of the Detwiler How do you measure a transom on an outboard motor? With the long side (22 1/2), place a carpenters square ) in opposition to the keel. https:/. Take your time and understand your boat and your entire transom. 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. The same is true for the newest, high-powered offshore fishing boats, where triple or quadruple motor setups are becoming more and more common. AztH ^zv_ cT,E1K/rAB54| s = d.createElement("script"); s.setAttribute("type", "text/javascript"); A big NO. Smaller 12-14 foot boats can require either a short or long shaft outboard depending on the style of the boat and the brand. 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. 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. Figuring out how to measure motor height on a The boat transom height is measured from the lowest point on the keel along the center line to the spot where the outboard motor's mounting holes bracket rests. Copyright 2017 Dealer Spike All Rights Reserved. Cavitation plates are used on the bottom components of boats to help them operate better. Always weigh the risks of making adjustments. 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. How to Measure Transom Height For vessels with transom-mounted outboards, you can easily figure out which type of outboard you need to get. 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. See diagram below. Beefier jack plates can be fitted should a boater be looking to mount an outboard with a shorter shaft than their transom demands. A2: Instead of changing to the short outboard shaft, you can try the Jack Plate first. These two measurements will give you the length of the shaft you need. Expectedly, when the transom angle is zero, it means it is flat. 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. Also, the boat will be more likely to hit bottom or submerge objects such as rocks or logs. height (that I'm aware of); probably the most common is: 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. And thats usually the case since the electric outboards are designed with larger and more efficient propeller that needs longer shaft. An outboard motor can drive just about any sort of boat with proper mounting. You also might not be able to lift the outboard out of the water entirely for storage. the propshaft below or above the pad. It is extremely important that the boater understands the significance of the transom's height. Among them will be first-timers or those who have recently purchased their boats. measuring; you may have to "extend" the flat part of the Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. 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). Your at your local outboard dealer shopping for a new motor and the salesman hits you with the question, "short or long shaft?". Then finally test your outboard, if the mount is perfect. Some fishing boats can handle the motor being underwater. So from there, I will try to help out by asking questions about your boat such as what type it is and the length. To do so, measure from the stern (back) of the boat to the midpoint of the hull on both sides. Beginning boaters should be aware of the boats measurements. This could also affect your travelling capabilities on the boat trailer. Actual shaft length is 21.5" on those. 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. jackplate to a point level with the top of the transom. Which Navigation Lights Does Your Boat Need? Not to measure boat speed, but to gauge the mounting height of the outboard motor on the boat transom. mpeInit(); and I'll explain it better, (or point you to someone that can help. Beginning boaters should be aware of the boats measurements. As a result, the issue is whether my boat need a short shaft or long shaft motor. Get the latest updates on new products and upcoming sales, 2023 Marine Parts Warehouse Incorporated There are 2 steps to help get a relatively accurate figure. Finding the right size is a matter of looking at what youve got and taking out the measuring tape. boats.com, 1221 Brickell Avenue, 23rd Floor, Miami, FL 33131, USA. As a yacht designer and boater, I prefer longer shafts. Whether you already own a boat or looking for your first watercraft we are here to service your needs. What the relationship to the pontoons is, I couldn't say. Whether your on a pontoon boat, fishing boat, or speedboat boating is always one of the best times you can have. bracket forward with a straight edge to where you can then measure up I run a 9.9 Mercury Bigfoot 20" shaft off the swim platform of my 89 Trophy 2160. The motor length corresponds to the transom height of the boat, measured from the keel to gunwale at the transom. In extremes, the engine can have overheating problems if the boat is raised to a point where the water inlets for the cooling system are out of the water. You'll need a short shaft outboard if it's 15 or less than an inch shorter. A reverse transom that sits too high can impact the propellers of the motor and motor bracket. It is where the outboard is mounted, and some boat owners place the name of the boat. Rebuilt - What You Need to Know, Lower Unit and Sterndrive Break-In Instructions. The motor is what powers the boat so the two go hand-in-hand. bracket. Add yours in the comment and Ill get back to you asap. To make the yard stick long enough to measure the length of all the clubs, tape the ruler to the top. In step 3, add another 10 cm (4") to the previous calculation in order to develop the ideal shaft length. If you decide to make adjustments, please consult a marine engine dealer about the boatdesign. (616) 364-0666, On all contiguous US part orders over $100. Place the rulers end on the ground behind the club and let the club to rest on top of it. Youll need a short shaft outboard if its 15 or less than an inch shorter. Each one has a totally different effect on the boats performance. This restriction includes most fishing boats and longer sailboats. Commonly, the transom angle ranges from 0-30 degrees, with the average transom angle set at 14 degrees. Oftentimes you will want to adjust the outboard shaft length in order to improve the boat performance such as speed. Smaller inflatables and dinghies needshort shaft motors, whilst bigger boats require long or, in some circumstances, extreme long shaft versions. As summer approaches there will be more boaters taking to the water. It is unsafe to have the engine block too close to the water on a low transom. 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. Bass boats, ski boats, or center cockpit vessels will want to double-check their measurements to get it just right. Ill also explain the difference between short and long shafts and how they vary by type of boat. Take a long straight edge, (long carpenter's level or long loadScript(ptScript); 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. Generally, the anti-ventilation plate on most engines is aligned with the bottom of the vessel. To do so, take a measurement from the very top to the very bottom of the transom in the precise center. The correct shaft length for your boat depends on a few factors. In lower mounting, the engine is set lower than the recommended standard. As mentioned above, the operation of the propeller relies on the transom height. 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. If you are looking to repower, they may be able to offer some sage advice. In the photo above, we've measured from the motor bracket to the top of You can use a longer shaft than recommended and your boat will work fine. By clicking Accept, you consent to the use of ALL the cookies. <>/Metadata 127 0 R/ViewerPreferences 128 0 R>> You dont have to be a mathematician to determine the correct boat transomangle. When the boattransom is too low, the motor could end up underwater. Brackets are also handy for boats that do not have flat transoms, like canoe-stern sailboats or fan-tailed motor vessels. 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. Measure from the top of the transom to the bottom of the hull. If you have a small boat with a 15 to 17 inch aft transom, youll most likely need a short shaft outboard. There is a simple test to see if your outboard motor is set at the best height. He is a I believe 20 to 21 inches is the optimum length for a lengthy shaft. The height of the boat transom dictates the size of the outboard motor. This email address is being protected from spambots. To break it down a bit more for you: Short shafts are 15-inches long. The engine must be linked to the transom at the proper height for a propeller to best meet specific boating demands. 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. Raising the motor increases the speed of the boat while decreasing the effort needed to turn the boat. Trimming in, trimming down, and trimming out are all terms that a beginning boater should learn. If you go too short your more than likely going to cavitate and loose power. However, you will need an understanding of how the degrees will alter the boats usability. Boat transom angles play a pivotal role in the flexibility of the boats trimming abilities. logoColor: "original", minAmount: 300.0, Recommended Engine Oil 2-Stroke Outboard Motor Oil. If the propeller fails to ventilate, the motor is mounted to low. It doesnt matter if you have a fiberglass boat, bay boat, big or small boat. Eq*^?6R83e+j}UY.(M7k]~4g)g ~wmS{ O7t/o(W|X? of the "bullet" on your lower unit. Workboats, sailboats, and displacement-hulled boats fall into this category. How Transom Height Is Measured document.getElementById('cloakd53b59933f6c3f2e8b59f1b4a6d41fa5').innerHTML = ''; This is probably the worst case scenario out of the two. You need JavaScript enabled to view it. Or it can have an angle degree as high as 30. You dont have to be a mathematician to determine the correct boat transom angle. Before we start measuring the outboard shaft length, lets get it clear about whats referring to when we talk about the outboard shaft length. If your boat is newer and the manufacturer is still in business, you might also want to try to give them a call. 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. gtag('js', new Date()); Measuring the shaft length can be done in various ways, but the most common way is by using a tape measure. Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. My family and I used it to fish, ski (yes, you can ski behind a pontoon boat), and cruise the lakes near our home. #1: Height Check the literature about your model boat online, and you may be surprised to find that the number is published for you. If you are running a twin-engine setup, then measure the same distance from each clamping plate to the bottom of the hull. }, 100); The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional". maxAmount: 6500.0, out the confusion. s.setAttribute("src", script); For boats equipped with a bracket, calculate the same measurement but based on the bracket and not the transom. endobj The pressure behind your hand dropped as you slid your hand back and forth through the water. You will also risk hitting bottom or submerge objects more frequently such as rocks or logs. 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. xmlHttp.setRequestHeader('Content-Type', 'application/json'); This exhaust port should be about 1 inch above the water line when the boat is idling. Picking the right shaft length for your outboard is an essential step in getting the best performance from your boat. It is where the outboard is mounted, and some boat owners place the name of the boat. To achieve this, the motor itself has to be attached at the correct height. 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? Also, how do you determine the length of an outboard transom? Most of the standard engined boats it takes shafts that are 15-30inches long. This distance is very important to the performance of you boat. This measurement was approximately 4". Now that you have a better understanding of boat transom heights its time to take out the ruler and get the perfect measurements. On this type of boat, if you are in doubt, default to the longer-shafted outboard. steel ruler, etc. These cookies track visitors across websites and collect information to provide customized ads. Measure from there down to the top of the cavitation plate, also known as the anti-ventilation plate. 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. Smaller boats may use adjustable jack plates that can be changed to fit any outboard. Other factors to consider when determining the mounting height of an outboard are related to performance. All boats are different, and the motor manufacturers produce a variety of standard lengths. 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. Shaft lengths are available in increments of 5. Here we will guide you in how to get the right boat transom height. Simply start with the engine in idle, followed by, If you decide to make some custom adjustments we have the. It was a 23-foot Crestliner Grand Cayman pontoon boat. var BCData = {"csrf_token":"d7ecb6b56891bb66aee12dbc01a80162b3ed582c1acbe30f16fc9f1b2abc362f"}; The transom angle is the vertical incline of the transom and is measured in degrees. Doing so, will put the propeller right below the boat. Next, measure from your centerline to where the outboard will be mounted on each side. One of the great things about an outboard motor is how versatile it is. A hydrofoil will typically level off the ride by driving the stern up and the bow down, and will stop or considerably minimize porposing on a 16 footer with a mid-sized outboard and no tabs, for example. Or measure from the main engine prop up to the water line? Theyre also useful if the back of your boat has a non-standard measurement. Youll also want to pay attention when youre in shallow water because your prop will be lower than normal. But, how do you measure it? The height of the boat transom dictates the size of the outboard motor. Thats a fairly simple list of symptoms, but if your motor is too low, youll probably notice at least one of them. up to the bottom of the motor brackets, (as in #1). Outboard motors can be fitted to a variety of boats, so manufacturers have standardized their engines to go on virtually anything. The collapsing bubbles are loaded with extremely low-pressure water vapor, which causes damage to a variety of surfaces as they collapse. The cookie is used to store the user consent for the cookies in the category "Analytics". Doing this can have adverse effects. (127 mm). It is extremely important that the boater understands the significance of the transoms height. This is somewhat similar to #2, in that you are again measuring with a Another important measurement is the transom angle. 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. 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. Step 2: Three Variables to Consider Triton. 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. a Detwiler manual jackplate. The prop will be in cleaner, harder water as it advances farther aft, making it more efficient. However, you will need an understanding of how the degrees will alter the boats usability. The clamp bracket is designed so that the engine's mounting height on the transom can be adjusted higher than standard. 12 Small Fishing Boat Accessories to Buy Today. Check out some hot FAQs to help you get the proper outboard shaft lengths. The performance of these boats depends on quite a lot of factors, but getting the outboard length just right is an essential first step. 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? We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. The transom is the boats flat vertical part at the back. 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. For most boaters this is a no brainer, but for the novice or inexperienced boater it may be a tougher question. What is the Virtual Sundance Film Festival? Then open up the clamp bucket. Buying a boat can be an exciting purchase.