What the relationship to the pontoons is, I couldn't say. since 1986. 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. trimming the motor out by one-half to full trim. 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. What are Apple Podcasts Subscriptions and Channels? document.getElementById('cloakd53b59933f6c3f2e8b59f1b4a6d41fa5').innerHTML = ''; storeDisplayName: "Marine Parts Warehouse", #2. brackets. Your email address will not be published. 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. I mean, who wants to purchase something as expensive as an outboard to only realize you bought the wrong one.
The cookie is used to store the user consent for the cookies in the category "Other. Among them will be first-timers or those who have recently purchased their boats. Measuring the shaft length can be done in various ways, but the most common way is by using a tape measure. All things considered, sticking with the industry standard is best for the beginner. If you are looking to repower, they may be able to offer some sage advice. Owners of bass boats, RIBs, or offshore fishing boats need to get this right. If the propeller fails to ventilate, the motor is mounted to low. 5/rC,aQhsK@Q. Gear case sits just below or at the hull depth due to the deep v. Many boat transoms are modified to use a different length of outboard by using a bracket. 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. var addyd53b59933f6c3f2e8b59f1b4a6d41fa5 = 'info' + '@'; You will also risk hitting bottom or submerge objects more frequently such as rocks or logs. Whether your on a pontoon boat, fishing boat, or speedboat boating is always one of the best times you can have. Other boats that need long shafts are. (In the case of the faster
Whether you already own a boat or looking for your first watercraft we are here to service your needs. Two years ago, I bought a Boston Whaler to fish off the coast. To do so, take a measurement from the very top to the very bottom of the transom in the precise center. 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. The transom angle is the vertical incline of the transom and is measured in degrees. Buying a boat can be an exciting purchase. How do you measure a transom on an outboard motor? This will be the
For over five years he has worked as a newspaper reporter and historic researcher. This email address is being protected from spambots. 7. However, the motor should not be raised more than 5 inches above the standard position. How Transom Height Is Measured It is possible that the motor could hang low while transporting on the boat trailer causing future boat repairs. 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. endobj
Take your time and understand your boat and your entire transom. The point where these measurements intersect is your centerline. 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. (We wont go into name-calling here, but the actual term for the cavitation plate is an anti-ventilation plate.) This would not be a good thing. The cookie is used to store the user consent for the cookies in the category "Performance". 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. These are vertically aligned so the boater can make adjustments. 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. displayMicroOffers: false, Its where the outboard motor is attached, and its also where some boat owners put the boats name. Finding the right size is a matter of looking at what youve got and taking out the measuring tape. This distance is very important to the performance of you boat. It can also improve the experience of driving a faster boat. The pressure behind your hand dropped as you slid your hand back and forth through the water. To sum up, there is a simple calculator of the shaft length for outboard motors: Outboard Shaft Length = Transom Height +/- Factors. If it measures between 17 and 22, you'll want to go with a long shaft motor. former editor at Boating Magazine and contributor to many national publications This illustration depicts four different outboard mounting height options (courtesy Mercury Marine). The transom is the boats flat vertical part at the back. You dont have to be a mathematician to determine the correct boat transomangle. Another important measurement is the transom angle. But in many cases, its a little more complicated than that alone. This cookie is set by GDPR Cookie Consent plugin. C Cheaptoon Cadet Joined Aug 4, 2010 Messages 28 Aug 24, 2010 #4 Re: Motor height on pontoon? Performance cookies are used to understand and analyze the key performance indexes of the website which helps in delivering a better user experience for the visitors. Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. Pretty easy to figure out but like I said its crucial to pairing a motor with a boat. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. What's the best height for my boat motor? Your goal is to measure how the outboard will sit, so start from the clamping plate and follow the centerline of the hull. Other factors to consider when determining the mounting height of an outboard are related to performance. Necessary cookies are absolutely essential for the website to function properly. Generally, short shaft outboards are 15 inches, long shaft outboards are 20 inches, and extra-long outboards are 25 inches. When mounting the engine, you want the cavitation plate to be 1 above the boat bottom for every 12 away from the transom. 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". Some boats are equipped with transom-hung outboards while others have a bracket. Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. Later in the article is an image that shows you exactly where to measure. On this type of boat, if you are in doubt, default to the longer-shafted outboard. 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. mpeSelector: ".pt-mpe", Beyond motorboats designed for large outboards, you will see outboards hanging on the sterns of everything from small canoes to large cruising sailboats. Actually there is no designated letter for short shaft. Some outboards have a serial number that tells you which shaft length to go for. 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. What Kind of Fuel Does Your Marine Engine Need? Attention: Remember to measure the outboard shaft length straight up and down instead of measuring along the transom. Although the longer outboard shaft length can lead to lower speed and more drag, the boat can push a heavier load. 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. var h = d.getElementsByTagName("head"), straight edge from the center of the pad, but this time you're measuring
These cookies track visitors across websites and collect information to provide customized ads. In lower mounting, the engine is set lower than the recommended standard. The average transom angle is around 14 degrees. The height of the boat transom dictates the size of the outboard motor. Knowing how this can affect the overall operation of the boat is a factor to be considered. Picking the right shaft length for your outboard is an essential step in getting the best performance from your boat. Check the literature about your model boat online, and you may be surprised to find that the number is published for you. var path = 'hr' + 'ef' + '='; A: The short answer is Yes. I would ask you to go back and measure the transom of your boat. 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. This, however, is not recommended for the beginning boater. The transom angle is the vertical incline of the transom and is measured in degrees. Boat transom angles play a pivotal role in the flexibility of the boats trimming abilities. It also cuts into speed and fuel efficiency. Then finally test your outboard, if the mount is perfect. For boats equipped with a bracket, calculate the same measurement but based on the bracket and not the transom. relation to pad
Determining Your Boat Transom Angle The transom angle - commonly measured in degrees - is the transom's vertical inclination. As a yacht designer and boater, I prefer longer shafts. The general guideline for longer shaft outboards is that the transom height should be at least 20 inches (50,8cm) above the waterline. This is a measurement that has been used for BassCats, I'm
Remember, if you use a longer outboard shaft than you need you will be increasing your draft. On the downside, a higher mount can interfere with the boaters steering capabilities. Propshaft in
Add the two measurements and you get 6 1/2". maxMicroAmount: 0.0, Doing this can have adverse effects. Read the measurement on the transoms bottom. Thats a fairly simple list of symptoms, but if your motor is too low, youll probably notice at least one of them. These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc. Why wont Touch ID be under the screen in the iPhone 15 and iPhone 16? 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. from the transom. How can you figure out what your transom angle is? window.dataLayer = window.dataLayer || []; Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. This was the height of my 225 Yamaha on my TR21
s.setAttribute("type", "text/javascript"); Another important measurement is the transom angle. var addy_textd53b59933f6c3f2e8b59f1b4a6d41fa5 = 'info' + '@' + 'vanssports' + '.' + 'com';document.getElementById('cloakd53b59933f6c3f2e8b59f1b4a6d41fa5').innerHTML += '
'+addy_textd53b59933f6c3f2e8b59f1b4a6d41fa5+'<\/a>'; 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. Be sure to measure carefully and research thoroughly before diving in. If you have an outboard motor, the distance from one end to another will be found on the side or on a label near its bottom. e-mail
Because of the increased friction, cavitation reduces efficiency. You reply, "Im not sure, I think its a long". It was a 23-foot Crestliner Grand Cayman pontoon boat. MPW eBay Store - Thousands of New OEM Old Stock Parts! What is Transom Height? What is the Virtual Sundance Film Festival? s.setAttribute("rel", "stylesheet"); 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. <>/ExtGState<>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 595.2 841.8] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>>
The motor is what powers the boat so the two go hand-in-hand. https://www.bornagainboating.com/Get Your Born Again Boating Clothing! The clamp bracket on the latest Mercury Four-Stoke-model outboards has five mounting bolt holes spaced .75 inches apart. Thats it. hulls, such as Allisons, Bullets, Strokers, etc., this measurement could
One of the great things about an outboard motor is how versatile it is. 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. There are also specialty motor shaft lengths. As mentioned above, the operation of the propeller relies on the transom height. Smaller boats may use adjustable jack plates that can be changed to fit any outboard. loadScript(ptScript); In the second photo, we've measure down from the top of the Detwiler
When the boattransom is too low, the motor could end up underwater. Mounting the motor lower on the boat transomcan createexcessive spray, increase case drag, reduce underwater clearance, and negatively impact faster boats. He is a Not to measure boat speed, but to gauge the mounting height of the outboard motor on the boat transom. On the downside, a higher mount can interfere with the boaters steering capabilities. So how to determine the outboard shaft length? 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. One of the main concerns is causing the engine to overheat if not enough water reaches the engine to keep it cool. In the case of a larger offshore boat, it may be to the top of a cutout on the . To do so, measure from the stern (back) of the boat to the midpoint of the hull on both sides. Your email address will not be published. Boats that use longer outboard shafts include: However, you will need an understanding of how the degrees will alter the boats usability. The flat part of the bracket that rests on the transom when mounted will give you the same point of reference as the transom does on the boat. Having the cavitation plate a bit lower than the transom is preferable to having it too high. 12 Small Fishing Boat Accessories to Buy Today. This is measured by the propeller shaft being parallel to the vessels bottom. As with anything, there are exceptions to the rule. Or measure from the main engine prop up to the water line? Read the following to get the optimal shaft length for outboard motors! Now that you have a better understanding of boat transom heights its time to take out the ruler and get the perfect measurements. Simply start with the engine in idle, followed bytrimming the motor out by one-half to full trim. 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. While this is the case there is certain saltwater motors that are extra extra long at 30 and 35 shaft. 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. Boaters who consider going with a higher mount can see increased speeds. To do so, you will want to measure at the exact center of the transom from the very top to the very bottom. Mounting the outboard a little bit lower than the standard point could avoid the possible ventilation and slip on acceleration. Take a long straight edge, (long carpenter's level or long
Boat hulls are designed in three basic types that range from slow displacement and semi-displacement hulls to the fastest planing hulls. gtag('js', new Date()); You can find your Mercury outboard model code on an ID plate or sticker. With a jack plate, you can mount it exactly where you want it. The propellers will also have trouble reaching the water. If you go too short your more than likely going to cavitate and loose power. In lower mounting, the engine is set lower than the recommended standard. This will ensure the best performance. You may wonder how deep your prop should be in the water. You need JavaScript enabled to view it. Brackets are also handy for boats that do not have flat transoms, like canoe-stern sailboats or fan-tailed motor vessels. Place the point of a yardstick at the middle of the top of the boat transom. A: The answer varies by boat, but here are some rules of thumb for matching a short shaft outboard to your boat. For really big boats, the biggest and baddest six- or eight-cylinder outboards can have extra-extra long shafts up to 30 inches. Measure straight down to the lowest point on the hull. Happy boating! This is handy if youre shopping for second-hand outboards or looking to sell the one that came with your boat. primeApr: 12.99, (3) Move horizontally across the chart until you hit the graph curve. var ptScript = "https://cdn.paytomorrow.com/js/pt-mpe.min.js"; Other boats that need extra long shafts are: Read my other articles on outboard motors. Check out some hot FAQs to help you get the proper outboard shaft lengths. If it measures anywhere from 17" to around 22", then your going to want to go with a long shaft motor. The boater must also consider if the boat transom support is designed to bear the weight of a higher mount. Recommended Engine Oil 2-Stroke Outboard Motor Oil. This, however, is not recommended for the beginning boater. logoColor: "original", 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? However, you will need an understanding of how the degrees will alter the boats usability. Knowing the width, height and depth of your transom allows you to make several important decisions when selecting or purchasing a new outboard. "brackets". Your goal is to measure how the outboard will sit, so start from the clamping plate and follow the centerline of the hull. This also means it can affect the safety of the boat. Lubrication System Engine Oil Mixed Gasoline. boats.com is part of the Boats Group Network. 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. var xmlHttp = new XMLHttpRequest(); manufacturer will recommend the outboard height according to the bracket shape and length. What Types of Documents Can be Sent to your Kindle Library? var prefix = 'ma' + 'il' + 'to'; Measure from there down to the top of the cavitation plate, also known as the anti-ventilation plate. function mpeInit() { (updated
If youre looking for a bracket that can handle motors of up to 10/15 horsepower, go no further. However, the motor should not be raised more than 5 inches above the standard position. It moves an outboard up and down to optimize performance and enable a boat to venture into shallower water than it might otherwise. 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. (function (d) { 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. the propshaft below or above the pad. A transom saver, which can change the spacing between the lower unit and the trailer, negates some of the support. Copyright 1999-2023 Boats Group. Raising an outboard higher on the transom can reduce drag and raise top speed. Boat transomangles play a pivotal role in the flexibility of the boats trimming abilities. He is also a certified marine technician and the author of a popular text on writing local history. Industry standards dictate that for short shaft engines the transom height should be 15. If you decide to make some custom adjustments we have theexperience and know-howto make it happen. Raising the motor increases the speed of the boat while decreasing the effort needed to turn the boat. This is measured by the propeller shaft being parallel to the vessels bottom. We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. xmlHttp.setRequestHeader('Content-Type', 'application/json'); 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. minAmount: 300.0, maxTerm: 36, 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. The mounting height of an outboard motor can impact the speed and handling characteristics of the boat. This is somewhat similar to #2, in that you are again measuring with a
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}'); PayTomorrow.mpeInit({ (616) 364-0666, On all contiguous US part orders over $100. The distance between the ends of a transom is measured in inches. 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.