how to measure transom height for outboard motor

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. In the past, though, it housed the officers and captain of 17th, 18th and 19th century sailing ships. *The Factors indicates the adjustment affected by on your boat type, the outboard working environment, and the transom distance as discussed above. The transom is the rear wall of the boat where the outboard engine is mounted in the middle. Here we look at the effects of standard, lower and higher mounting. Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. It also cuts into speed and fuel efficiency. Other boats that need long shafts are. When the boattransom is too low, the motor could end up underwater. 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. 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. This illustration depicts four different outboard mounting height options (courtesy Mercury Marine). The cookie is used to store the user consent for the cookies in the category "Other. %PDF-1.7 of the "bullet" on your lower unit. The motor is what powers the boat so the two go hand-in-hand. actually have the propshaft above the pad.). If the propeller fails to ventilate, the motor is mounted to low. ensure that your measurement is accurate. Plus, a low transom cut is an invitation for the water to flood the boat. If you have a jackplate, you may have to get a bit creative in your stream xmlHttp.open('POST', 'https://bes.gcp.data.bigcommerce.com/nobot'); var addy_textd53b59933f6c3f2e8b59f1b4a6d41fa5 = 'info' + '@' + 'vanssports' + '.' + 'com';document.getElementById('cloakd53b59933f6c3f2e8b59f1b4a6d41fa5').innerHTML += ''+addy_textd53b59933f6c3f2e8b59f1b4a6d41fa5+'<\/a>'; Oftentimes you will want to adjust the outboard shaft length in order to improve the boat performance such as speed. Among them will be first-timers or those who have recently purchased their boats. If your outboard motor height. 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. Simply start with the engine in idle, followed bytrimming the motor out by one-half to full trim. He is also a certified marine technician and the author of a popular text on writing local history. Its still smart to measure it yourself though, just in case, the design changed over the years. This will ensure the best performance. 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. motor brackets Read the measurement on the transoms bottom. Engine Oil Type Genuine or Recommended 2str Engine Oil. trimming the motor out by one-half to full trim. If it measures 15" or with in a inch of that you will need a short shaft outboard. While this is the case there is certain saltwater motors that are extra extra long at 30 and 35 shaft. If you are running a twin-engine setup, then measure the same distance from each clamping plate to the bottom of the hull. This measurement was approximately 4". Beyond motorboats designed for large outboards, you will see outboards hanging on the sterns of everything from small canoes to large cruising sailboats. Step 2: Three Variables to Consider Each one has a totally different effect on the boats performance. PayTomorrow.mpeInit({ primeApr: 12.99, These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc. There is a simple test to see if your outboard motor is set at the best height. 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). You can use a longer shaft than recommended and your boat will work fine. You Analytical cookies are used to understand how visitors interact with the website. Selecting the Correct Size Outboard Shaft, What is the Best Outboard Motor for Saltwater, Diagnosing Common Outboard Motor Problems, Best Beginner Boats Everything You Need to Know. You need JavaScript enabled to view it. This restriction includes most fishing boats and longer sailboats. This provides seaworthiness and offers maximum protection from large seas. 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. It is where the outboard is mounted, and some boat owners place the name of the boat. Doing so, will put the propeller right below the boat. This is simply a measurement taken from the top of the transom (top of But opting out of some of these cookies may affect your browsing experience. Is my outboard long or short shaft? If you went too long it would still work but it may lack in performance. To achieve this, the motor itself has to be attached at the correct height. Boaters who consider going with a higher mount can see increased speeds. The vertical distance between the interior of the clamp and the cavitation plate is the shaft length specified by the outboard manufacturer. As mentioned above, the operation of the propeller relies on the transom height. The form of a boats transom varies depending on the manufacturer and model. parallel with the straight edge. To do so, measure from the stern (back) of the boat to the midpoint of the hull on both sides. Read the following to get the optimal shaft length for outboard motors! They operate as a planing surface, allowing your boat to climb to the top more quickly. For example, you can have the Mercury outboard shaft length by model code. 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. You can find your Mercury outboard model code on an ID plate or sticker. See diagram below. If it measures anywhere from 17" to around 22", then your going to want to go with a long shaft motor. This placement is not only recommended but it will give you the best performance compared to something that is too long or too short. Your email address will not be published. If you have a question or need additional information. var h = d.getElementsByTagName("head"), Gear Oil Quantity 195ml(6.6 Fl.oz.) 2 0 obj Shaft lengths are available in increments of 5. In lower mounting, the engine is set lower than the recommended standard. Any questions? Knowing how this can affect the overall operation of the boat is a factor to be considered. brackets. Now that you have a better understanding of boat transom heights its time to take out the ruler and get the perfect measurements. boats.com is part of the Boats Group Network. Like Westshore Marine & Leisure on Facebook! Where Onboard a Boat is the Transom Located and More About Transom Heights A propeller operates based on the height of the transom. Not to measure boat speed, but to gauge the mounting height of the outboard motor on the boat transom. A: Any boat that has a 21 to 27 inch aft transom will need an extra long shaft outboard. 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. 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. not sure that it's still used. Although the longer outboard shaft length can lead to lower speed and more drag, the boat can push a heavier load. If you are looking to repower, they may be able to offer some sage advice. August 9/08). You need JavaScript enabled to view it. Boaters who consider going with a higher mount can see increased speeds. 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. (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. This cookie is set by GDPR Cookie Consent plugin. Happy boating! It also includes attaching the right engine. Engine Oil Mixing Ratio Fuel 50: Engine Oil 1. loadScript(ptScript); 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. The transom is the flat vertical section at the rear of the boat. Place the point of a yardstick at the middle of the top of the boat transom. Outboards designed for saltwater applications usually have longer shafts. The outboard comes with mounting holes and brackets. What types of boat need an extra long shaft? Mounting the outboard a little bit lower than the standard point could avoid the possible ventilation and slip on acceleration. What matters is the actual measurement in the specifications, not the name. Buying a boat can be an exciting purchase. Measure from the top of the straight edge to the center of the front It does not store any personal data. Before we get started lets see what a boat transom is and what it does. The motor length corresponds to the transom height of the boat, measured from the keel to gunwale at the transom. Rebuilt - What You Need to Know, Lower Unit and Sterndrive Break-In Instructions. How do you measure a transom on an outboard motor? d.addEventListener("DOMContentLoaded", function (e) { 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. All rights reserved. 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. Your goal is to measure how the outboard will sit, so start from the clamping plate and follow the centerline of the hull. And thats usually the case since the electric outboards are designed with larger and more efficient propeller that needs longer shaft. Look at the part of your motor that would be Check out some hot FAQs to help you get the proper outboard shaft lengths. priceSelector: ".price--withoutTax, span.price.price--withTax", However, there may be times when a boater strays away from these recommendations. Knowing how this can affect the overall operation of the boat is a factor to be considered. 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. To sum up, there is a simple calculator of the shaft length for outboard motors: Outboard Shaft Length = Transom Height +/- Factors. What is the Virtual Sundance Film Festival? Depending on the manufacturer, size names might change. It doesnt matter if you have a fiberglass boat, bay boat, big or small boat. What Kind of Fuel Does Your Marine Engine Need? Copyright 2017 Dealer Spike All Rights Reserved. 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 moves an outboard up and down to optimize performance and enable a boat to venture into shallower water than it might otherwise. If you go too short your more than likely going to cavitate and loose power. the propshaft below or above the pad. Youll need a short shaft outboard if its 15 or less than an inch shorter. Many boat transoms are modified to use a different length of outboard by using a bracket. Or it can have an angle degree as high as 30. If it measures 15" or with in a inch of that you will need a short shaft outboard. Why wont Touch ID be under the screen in the iPhone 15 and iPhone 16? #1: Height The transom angle is the vertical incline of the transom and is measured in degrees. Check the literature about your model boat online, and you may be surprised to find that the number is published for you. A deep Vee hull will result in a different measurement than a flatter . 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. 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. The clamp bracket is designed so that the engine's mounting height on the transom can be adjusted higher than standard. The point where these measurements intersect is your centerline. How to Measure Transom Height For vessels with transom-mounted outboards, you can easily figure out which type of outboard you need to get. For slower boats, its less critical to. A transom saver, which can change the spacing between the lower unit and the trailer, negates some of the support. Then finally test your outboard, if the mount is perfect. Place the clubs bottom on the ground as though it were going to be used to strike a golf ball. 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 height of the boat transom dictates the size of the outboard motor. For over five years he has worked as a newspaper reporter and historic researcher. (127 mm). height (that I'm aware of); probably the most common is: Raising an outboard higher on the transom can reduce drag and raise top speed. maxAmount: 6500.0, There are instances where a lower mount may be okay. Because of the increased friction, cavitation reduces efficiency. } function mpeInit() { The mounting height of an outboard motor can impact the speed and handling characteristics of the boat. What Types of Documents Can be Sent to your Kindle Library? manufacturer will recommend the outboard height according to the bracket shape and length. To make the yard stick long enough to measure the length of all the clubs, tape the ruler to the top. It is extremely important that the boater understands the significance of the transom's height. Make sure that you are measuring straight up, at a 90 degree angle to 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. It is where the outboard is mounted, and some boat owners place the name of the boat. In addition, motor totes will not harm the finish of the lower unit. The brackets can add 1 inch to the overall mounting height of the outboard. debugMode: false, var interval = setInterval(function () { 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. |. Simply start with the engine in idle, followed by trimming the motor out by one-half to full trim. If it measures anywhere from 17" to around 22", then your going to want to go with a long shaft motor. When the boat transom is too low, the motor could end up underwater. Any owner seeking the last bit of speed from an outboard-powered boat should grab a yard stick. Among them will be first-timers or those who have recently purchased their boats. Then test the boat and adjust the height, if necessary . h[0].appendChild(s); It was a 23-foot Crestliner Grand Cayman pontoon boat. If you have a small boat with a 15 to 17 inch aft transom, youll most likely need a short shaft outboard. An outboard motor can drive just about any sort of boat with proper mounting. It is extremely important that the boater understands the significance of the transoms height. bracket. Repowering your boat is one of the most expensive upgrades you can make. your motor will be higher.) With some boats I have a pretty good idea as to what length motor should be hung on them. 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. 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. AztH ^zv_ cT,E1K/rAB54| To achieve 35 mph with a 6 hp engine, the total weight is 135 lbs (boat motor fuel passengers). 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. Wherever the outboard clamping bracket is, use this as the basis for measurement. 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 is measured by the propeller shaft being parallel to the vessels bottom. Then, you can pick the right engine. 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. Mounting the outboard motor in accordance with the industry standards is important. 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. This was the height of my 225 Yamaha on my TR21 Small portable outboards ranging from 2 to 20 horsepower are usually sold only in short or long shaft versions. This, however, is not recommended for the beginning boater. The propellers will also have trouble reaching the water. Your at your local outboard dealer shopping for a new motor and the salesman hits you with the question, "short or long shaft?". All boats are different, and the motor manufacturers produce a variety of standard lengths. Say the 20 shaft is a long shaft length for gas engines, but it is a short shaft length for electric outboard motors. center of the propshaft. You also might not be able to lift the outboard out of the water entirely for storage. The pros and cons of properly . Some outboards have a serial number that tells you which shaft length to go for. My family and I used it to fish, ski (yes, you can ski behind a pontoon boat), and cruise the lakes near our home. What are Apple Podcasts Subscriptions and Channels? The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional". <> To achieve this, the motor itself has to be attached at the correct height. High powered boats usually only come in long and extra-long variants. function gtag(){dataLayer.push(arguments);} All things considered, sticking with the industry standard is best for the beginner. 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. Higher mounting decisions should be left to the professionals. One of the great things about an outboard motor is how versatile it is. I mean, who wants to purchase something as expensive as an outboard to only realize you bought the wrong one. 12 Small Fishing Boat Accessories to Buy Today. Outboard shaft length plays a crucial role in the performance of your boat. 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. It is very versatile as it generally . Brackets are also handy for boats that do not have flat transoms, like canoe-stern sailboats or fan-tailed motor vessels. Some fishing boats can handle the motor being underwater. Your email address will not be published. This could also effect your travelling capabilities on the boat trailer. You dont have to be a mathematician to determine the correct boat transomangle. Use the mounting bracket on the motor to know where it will sit on the boat. 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. A: The short answer is Yes. jackplate to a point level with the top of the transom. Its important to note that manufacturers call their models different things. Over time, Boating Hub has grown into a resource for boating enthusiasts around world. Take your time and understand your boat and your entire transom. Will Charpentier is a writer who specializes in boating and maritime subjects. 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. storeDisplayName: "Marine Parts Warehouse", 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. disregard the downward pointing "hooks" at the front of the The amount of degrees the transom leans back from vertical is known as the transom angle. <>/Metadata 127 0 R/ViewerPreferences 128 0 R>> You will also risk hitting bottom or submerge objects more frequently such as rocks or logs. When fighting waves from the stern, a 20-inch transom is considerably safer. Boat transom angles play a pivotal role in the flexibility of the boats trimming abilities. 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. 7. The pressure behind your hand dropped as you slid your hand back and forth through the water. What's the best height for my boat motor? Boats that use longer outboard shafts include: Spark Plug 25.0nm(18.4 Ft-lb) (2.55 Kgf-m) Smaller boats may use adjustable jack plates that can be changed to fit any outboard. Whether you already own a boat or looking for your first watercraft we are here to service your needs. The general guideline for longer shaft outboards is that the transom height should be at least 20 inches (50,8cm) above the waterline. These allow the mounting of a standard length outboard behind the transom. boats.com, 1221 Brickell Avenue, 23rd Floor, Miami, FL 33131, USA. If the height of the boat transom is off it can cause major issues. Check out the Westshore Marine & Leisure Youtube page! Having the cavitation plate a bit lower than the transom is preferable to having it too high. 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 decide to make some custom adjustments we have theexperience and know-howto make it happen. He is a Long shafts are 20-inches long. If the height of the boat transom is off it can cause major issues. s = d.createElement("link"); Bass boats, ski boats, or center cockpit vessels will want to double-check their measurements to get it just right. By clicking Accept, you consent to the use of ALL the cookies. A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. Owners of bass boats, RIBs, or offshore fishing boats need to get this right. Another important measurement is the transom angle. Here we will guide you in how to get the right boat transom height. 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. 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. Before we get started lets see what a boat transom is and what it does. I live for the weekends when I can go out on the water and escape the stress of life on land. This website uses cookies to improve your experience while you navigate through the website. https:/. if (PayTomorrow) { "brackets". Generally, short shaft outboards are 15 inches, long shaft outboards are 20 inches, and extra-long outboards are 25 inches. Which Navigation Lights Does Your Boat Need? However, you will need an understanding of how the degrees will alter the boats usability. The how to measure the shaft length of an outboard motor is a question that many people have asked. As you can see, the measurement is about 2 1/2". The cookies is used to store the user consent for the cookies in the category "Necessary". Re: Dinghy with a long shaft motor? It also decreases the boats lift and increases the time it takes for the boat to reach plane. 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. With it comes a lot of responsibility and new things to learn includingboat maintenanceand boat basics. bassboat can be a bit confusing at times; hopefully this will help sort 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 performance of these boats depends on quite a lot of factors, but getting the outboard length just right is an essential first step. var path = 'hr' + 'ef' + '='; As with anything, there are exceptions to the rule. For boats equipped with a bracket, calculate the same measurement but based on the bracket and not the transom. The first order of business is to measure your boat for the ideal fit. Trimming in, trimming down, and trimming out are all terms that a beginning boater should learn. It also cuts into speed and fuel efficiency. See When St. Peters Basketball Games Are Today! 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. Using your existing control box and gauges will save you quite a bit of money in the end. Most of the standard engined boats it takes shafts that are 15-30inches long. Whats the best height for my boat motor? The engine may be lifted one inch for every eight to ten inches of distance between the transom and the prop, according to a boat riggers rule of thumb. Anything bigger than that your obviously going to need an extra long shaft. Then open up the clamp bucket. What the relationship to the pontoons is, I couldn't say. A yardstick will help you determine if your outboard engine is at the right height. Before we start measuring the outboard shaft length, lets get it clear about whats referring to when we talk about the outboard shaft length. Always weigh the risks of making adjustments. Determining Your Boat Transom Angle The transom angle - commonly measured in degrees - is the transom's vertical inclination. The same is true for the newest, high-powered offshore fishing boats, where triple or quadruple motor setups are becoming more and more common. from the transom. As with anything, there are exceptions to the rule. A1: Broadly speaking, the outboard motor shaft length for pontoon boat, bass boat, or other larger boats should be long shaft. This is probably the worst case scenario out of the two. The standard shaft length for most outboard engines less than 125 horsepower is 20 inches. The motor is what powers the boat so the two go hand-in-hand. Boat transomangles play a pivotal role in the flexibility of the boats trimming abilities. To do so, you will want to measure at the exact center of the transom from the very top to the very bottom. 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. Other uncategorized cookies are those that are being analyzed and have not been classified into a category as yet. All you need to do is measure how much to rise. Take a long straight edge, (long carpenter's level or long straight edge from the center of the pad, but this time you're measuring minAmount: 300.0, The average transom angle is around 14 degrees. Actual shaft length is 21.5" on those. 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.