xmlHttp.setRequestHeader('Content-Type', 'application/json'); trimming the motor out by one-half to full trim. Anything bigger than that your obviously going to need an extra long shaft. 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. Youll need a short shaft outboard if its 15 or less than an inch shorter. Pad to bottom of Commonly, the transom angle ranges from 0-30 degrees, with the average transom angle set at 14 degrees. If you have a question or need additional information. Displacement hulled vessels like sailboats and workboats can benefit from a little more space between the hull and cavitation plate, but not much. Your at your local outboard dealer shopping for a new motor and the salesman hits you with the question, "short or long shaft?". 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. 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. Functional cookies help to perform certain functionalities like sharing the content of the website on social media platforms, collect feedbacks, and other third-party features. Is my outboard long or short shaft? To make the yard stick long enough to measure the length of all the clubs, tape the ruler to the top. What Types of Documents Can be Sent to your Kindle Library? }, 100); Should I take the raft onto the water and measure the exact distance from the top of the transom to the water line? I show you how to consistently measure your prop to pad height. Where Onboard a Boat is the Transom Located and More About Transom Heights A propeller operates based on the height of the transom. Now that you have a better understanding of boat transom heights its time to take out the ruler and get the perfect measurements. What's the best height for my boat motor? Sailboats use these sometimes, as well as some boaters who want to install a much smaller auxiliary motor to use in case of primary engine failure. This could also affect your travelling capabilities on the boat trailer. Why wont Touch ID be under the screen in the iPhone 15 and iPhone 16? There are a series of four to six holes at the top of the bracket, and the lower bolts actually fit into slots. Other boats that need long shafts are. var prefix = 'ma' + 'il' + 'to'; How to Measure Transom Height For vessels with transom-mounted outboards, you can easily figure out which type of outboard you need to get. former editor at Boating Magazine and contributor to many national publications Here we will guide you in how to get the right boat transom height. The boat transom can be flat with zero degree angles. And the rule of thumb is that you should keep the cavitation plate level with the bottom or keel of the boat. Of course, its always best to go with standard practices when choosing thebest boat engine. Trimming in, trimming down, and trimming out are all terms that a beginning boater should learn. This is simply a measurement taken from the top of the transom (top of If the height of the boat transom is off it can cause major issues. 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). Expectedly, when the transom angle is zero, it means it is flat. There is a simple test to see if your outboard motor is set at the best height. e-mail When the boattransom is too low, the motor could end up underwater. How can you figure out what your transom angle is? Before we get started lets see what a boat transom is and what it does. 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. Smaller 12-14 foot boats can require either a short or long shaft outboard depending on the style of the boat and the brand. 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. 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. The general guideline for longer shaft outboards is that the transom height should be at least 20 inches (50,8cm) above the waterline. Many single-engine boats mount a smaller auxiliary motor for emergency use. Your email address will not be published. To do so, measure from the stern (back) of the boat to the midpoint of the hull on both sides. Follow Westshore Marine & Leisure on Wordpress! This measurement would be the inches of (Putting a Here we will guide you in how to get the right boat transom height. What Kind of Fuel Does Your Marine Engine Need? 3 0 obj Measure straight down to the lowest point on the hull. Finding the right size is a matter of looking at what youve got and taking out the measuring tape. But in many cases, its a little more complicated than that alone. Analytical cookies are used to understand how visitors interact with the website. of the motor off the transom Each one has a totally different effect on the boats performance. With this in mind, how can I determine if my outboard has a short or long shaft? Workboats, sailboats, and displacement-hulled boats fall into this category. Gear case sits just below or at the hull depth due to the deep v. 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. So from there, I will try to help out by asking questions about your boat such as what type it is and the length. The outboard shaft length is the vertical distance between the top of the mounting clamp bracket and the bottom of the cavitation plate (aka the ventilation plate). 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. 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. If you said something smaller than that, thats where it can get tricky. publicId: "32bf3437d1346295e03ebcf545f9c839", It doesnt matter if you have a fiberglass boat, bay boat, big or small boat. The outboard comes with mounting holes and brackets. If your boat planes, pay extra attention to getting the shaft length as close to perfect as possible. Be sure to measure carefully and research thoroughly before diving in. Also, how do you determine the length of an outboard transom? 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. Measure the area of the transom directly where the engine will be mounted. Over time, Boating Hub has grown into a resource for boating enthusiasts around world. Measure from the top of the transom to the bottom of the hull. The shaft length for outboard motors has nothing to do with the water line. Follow Westshore Marine & Leisure on Twitter! The propellers will also have trouble reaching the water. If you have a small boat with a 15 to 17 inch aft transom, youll most likely need a short shaft outboard. 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. Remember, if you use a longer outboard shaft than you need you will be increasing your draft. out the confusion. When trimming your motor, they provide you a greater bow response. Since the length of the shaft of your outboard is associated with the size boat, smaller engines will generally have shorter shafts. The height of the boat transom dictates the size of the outboard motor. On the downside, a higher mount can interfere with the boaters steering capabilities. Here we look at the effects of standard, lower and higher mounting. With the long side (22 1/2), place a carpenters square ) in opposition to the keel. Necessary cookies are absolutely essential for the website to function properly. 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. Take your time and understand your boat and your entire transom. The transom is the "back wall" of your boat, the most rearward part of your hull. gtag('js', new Date()); Plus, a low transom cut is an invitation for the water to flood the boat. This would not be a good thing. Then test the boat and adjust the height, if necessary . Tightening Torque for Engine. It is possible that the motor could hang low while transporting on the boat trailer causing future boat repairs. Most of the time, adding a hydrofoil to an outboard improves performance. The distance between the ends of a transom is measured in inches. Check out some hot FAQs to help you get the proper outboard shaft lengths. 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. A deep Vee hull will result in a different measurement than a flatter . And thats usually the case since the electric outboards are designed with larger and more efficient propeller that needs longer shaft. It also decreases the boats lift and increases the time it takes for the boat to reach plane. As with anything, there are exceptions to the rule. It is where the outboard is mounted, and some boat owners place the name of the boat. 12 Small Fishing Boat Accessories to Buy Today. straight edge from the center of the pad, but this time you're measuring It is unsafe to have the engine block too close to the water on a low transom. They keep water out of your prop and increase water pressure in the system. This alone can outweigh the negatives when deciding to adjust the mount upwards. disregard the downward pointing "hooks" at the front of the So how to determine the outboard shaft length? A reversetransom that sits too high can impact the propellers of the motor and motor bracket. Boats with more engine power and weight require longer shaft outboards for better balance. from the transom. Measure from there down to the top of the cavitation plate, also known as the anti-ventilation plate. If it measures between 17 and 22, you'll want to go with a long shaft motor. Measure from the top of the straight edge to the center of the front 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. Some outboards have a serial number that tells you which shaft length to go for. The pressure behind your hand dropped as you slid your hand back and forth through the water. Some fishing boats can handle the motor being underwater. Move the bracket as close to the center of the transom as possible while still maintaining clearance to allow the main outboard or rudder to reach its full range of motion without contacting the kicker motor. Recommended Engine Oil 2-Stroke Outboard Motor Oil. 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. This is measured by the propeller shaft being parallel to the vessels bottom. If you go too short your more than likely going to cavitate and loose power. Boaters who consider going with a higher mount can see increased speeds. Many boat transoms are modified to use a different length of outboard by using a bracket. They operate as a planing surface, allowing your boat to climb to the top more quickly. This allows the engine to idle without the flow of the exhaust being restricted. Take your time and understand your boat and your entire transom. Mounting the outboard motor in accordance with the industry standards is important. Engine Oil Mixing Ratio Fuel 50: Engine Oil 1. Your email address will not be published. Which Navigation Lights Does Your Boat Need? Read the following to get the optimal shaft length for outboard motors! 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. However, the motor should not be raised more than 5 inches above the standard position. To achieve this, the motor itself has to be attached at the correct height. https:/. The average transom angle is around 14 degrees. 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. Raising the motor increases the speed of the boat while decreasing the effort needed to turn the boat. Rest the yard stick or another suitable straight edge along the keel on the bottom of the boat so that it makes a straight line aft to the outboard. if (PayTomorrow) { 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. 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. Read the measurement on the transoms bottom. Mounting the outboard motor in accordance with the industry standards is important. Knowing the width, height and depth of your transom allows you to make several important decisions when selecting or purchasing a new outboard. This is measured by the propeller shaft being parallel to the vessels bottom. Higher mounting decisions should be left to the professionals. bracket. This is a measurement that has been used for BassCats, I'm The form of a boats transom varies depending on the manufacturer and model. var h = d.getElementsByTagName("head"), A1: Broadly speaking, the outboard motor shaft length for pontoon boat, bass boat, or other larger boats should be long shaft. Save my name, email, and website in this browser for the next time I comment. High powered boats usually only come in long and extra-long variants. This, however, is not recommended for the beginning boater. h[0].appendChild(s); You dont have to be a mathematician to determine the correct boat transomangle. If you decide to make some custom adjustments we have theexperience and know-howto make it happen. These allow the mounting of a standard length outboard behind the transom. Like Westshore Marine & Leisure on Facebook! #1: Height 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. 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. An inch or two probably wont make a big difference, but any more than that will lead to trouble. Take a long straight edge, (long carpenter's level or long clearInterval(interval); Ask a friend to hold one end of a measuring tape at the extreme outer edge of the top of the transom while you pull the tape across its width to the opposite outer edge to measure the "length of the taffrail," which is the width of the boat across the top edge of the stern. Higher mounting decisions should be left to the professionals. Picking the right shaft length is mostly a factor of the transom height or the back of the boat. To do so, take a measurement from the very top to the very bottom of the transom in the precise center. There It is extremely important that the boater understands the significance of the transom's height. What are Apple Podcasts Subscriptions and Channels? A: The short answer is Yes. Place the point of a yardstick at the middle of the top of the boat transom. parallel with the straight edge. The propellers will also have trouble reaching the water. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. Other boats that need extra long shafts are: Read my other articles on outboard motors. The collapsing bubbles are loaded with extremely low-pressure water vapor, which causes damage to a variety of surfaces as they collapse. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. Raising the motor increases the speed of the boat while decreasing the effort needed to turn the boat. The boater must also consider if the boat transom support is designed to bear the weight of a higher mount. Top 10 Choices for Boaters, Mercury Introduces 600HP V12 Verado Outboard Engine, The Outboard Expert: Tohatsu Propane Outboard Engine. Boat Transom Heights The Beginners Guide, Buying a boat can be an exciting purchase. of the "bullet" on your lower unit. You can use a longer shaft than recommended and your boat will work fine. var addyd53b59933f6c3f2e8b59f1b4a6d41fa5 = 'info' + '@'; 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. Offshore vessels are often equipped with a large mounting bracket so that the transom can be left at full height. Mounting the motor lower on the boat transomcan createexcessive spray, increase case drag, reduce underwater clearance, and negatively impact faster boats. These are vertically aligned so the boater can make adjustments. Shaft lengths are available in increments of 5. If you decide to make adjustments, please consult a marine engine dealer about the boat design. Boaters who consider going with a higher mount can see increased speeds. Measure from the top of the transom to the bottom of the hull. Set the end of the tape on the outside edge of the taffrail at the center and measure inward to the inside edge of the taffrail. 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. If it measures anywhere from 17" to around 22", then your going to want to go with a long shaft motor. Or it can have an angle degree as high as 30. The motor is what powers the boat so the two go hand-in-hand. 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. You'll need a short shaft outboard if it's 15 or less than an inch shorter. His works have appeared in regional newspapers in North Dakota and in "North Dakota Horizons" and "Cowboys and Indians" magazines. Repowering your boat is one of the most expensive upgrades you can make. The correct shaft length for your boat depends on a few factors. This is probably the worst case scenario out of the two. 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. Or measure from the main engine prop up to the water line? Boats that use longer outboard shafts include: Setting Height of Outboard Motor - YouTube 0:00 / 0:46 Setting Height of Outboard Motor nates90 71 subscribers Subscribe 83 Share 63K views 7 years ago #boatservice #outboardmotor. Whether you already own a boat or looking for your first watercraft we are here to service your needs. Most of the standard engined boats it takes shafts that are 15-30inches long. maxAmount: 6500.0, <> priceSelector: ".price--withoutTax, span.price.price--withTax", When fighting waves from the stern, a 20-inch transom is considerably safer. #2. disregard the "hooks" at the front of the Generally, the anti-ventilation plate on most engines is aligned with the bottom of the vessel. Knowing how this can affect the overall operation of the boat is a factor to be considered. However, your boat will have slightly more drag which will reduce your maximum speed. The cavitation plate is the horizontal surface of the lower unit immediately above the propeller. The average transom angle is around 14 degrees. If youre looking for a bracket that can handle motors of up to 10/15 horsepower, go no further. These two measurements will give you the length of the shaft you need. C Cheaptoon Cadet Joined Aug 4, 2010 Messages 28 Aug 24, 2010 #4 Re: Motor height on pontoon? There is a simple test to see if your outboard motor is set at the best height. 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). So how to measure outboard shaft length? Your goal is to measure how the outboard will sit, so start from the clamping plate and follow the centerline of the hull. Look at the part of your motor that would be On the downside, a higher mount can interfere with the boaters steering capabilities. Triton. https://www.bornagainboating.com/Get Your Born Again Boating Clothing! Measuring the shaft length can be done in various ways, but the most common way is by using a tape measure. If it measures anywhere from 17" to around 22", then your going to want to go with a long shaft motor. If you are running a slower boat, the exact location of the ventilation plate is less important. 5/rC,aQhsK@Q. The anti-cavitation plate above the prop needs to be within an inch of the bottom of the transom, therefore, the prop should be well below the transom. Propshaft in A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. 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. It also includes attaching the right engine. Place the bracket on the transom to the left of the main outboard or rudder. manufacturer will recommend the outboard height according to the bracket shape and length. See diagram below. Industry standards dictate that for short shaft engines the transom height should be 15. 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. Extra-extra long shafts are 30-inches long. A yardstick will help you determine if your outboard engine is at the right height. maxTerm: 36, Its still smart to measure it yourself though, just in case, the design changed over the years. actually have the propshaft above the pad.). boats.com is part of the Boats Group Network. 2 0 obj But, how do you measure it? This website uses cookies to improve your experience while you navigate through the website. 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. Among them will be first-timers or those who have recently purchased their boats. The cookies is used to store the user consent for the cookies in the category "Necessary". var ptScript = "https://cdn.paytomorrow.com/js/pt-mpe.min.js"; 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. 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. I would also recommend finding your maximum horsepower rating which is located on the yellow coast guard tag towards the back of your boat. gtag('config', 'G-QX0Y76NH40'); Whether your on a pontoon boat, fishing boat, or speedboat boating is always one of the best times you can have. 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). I live for the weekends when I can go out on the water and escape the stress of life on land. What types of boat need an extra long shaft? <>/ExtGState<>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 595.2 841.8] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> Outboards designed for saltwater applications usually have longer shafts. The transom is the rear wall of the boat where the outboard engine is mounted in the middle. bracket forward with a straight edge to where you can then measure up var addy_textd53b59933f6c3f2e8b59f1b4a6d41fa5 = 'info' + '@' + 'vanssports' + '.' + 'com';document.getElementById('cloakd53b59933f6c3f2e8b59f1b4a6d41fa5').innerHTML += ''+addy_textd53b59933f6c3f2e8b59f1b4a6d41fa5+'<\/a>'; Beginning boaters should be aware of the boats measurements. Mounting the outboard a little bit lower than the standard point could avoid the possible ventilation and slip on acceleration. ), and place it on the bottom of the pad in the center. 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. As mentioned above, the operation of the propeller relies on the transom height. 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. window.dataLayer = window.dataLayer || []; The transom is the flat vertical section at the rear of the boat. What is Transom Height? 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. Beginning boaters should be aware of the boats measurements. (3) Move horizontally across the chart until you hit the graph curve. would be more accurate.) As mentioned above, the operation of the propeller relies on the transom height. Another important measurement is the transom angle. The height of the boat transom dictates the size of the outboard motor. Re: Dinghy with a long shaft motor? Two years ago, I bought a Boston Whaler to fish off the coast. Save my name, email, and website in this browser for the next time I comment. Add the two measurements and you get 6 1/2". How the outboard will sit on the back of the boat depends on how the transom is designed. There are instances where a lower mount may be okay. Oftentimes you will want to adjust the outboard shaft length in order to improve the boat performance such as speed. According to MarinePartsMan.com, the outboard can be raised 1 inch above the standard height for every 10 miles per hour of speed the boat can attain. If the propeller fails to ventilate, the motor is mounted to low. | Sitemap, The Marine Parts Warehouse Outboard Museum, OBR Powerhead / Shortblock Warranty Claim Form, Remanufactured vs. In the photo above, we've measured from the motor bracket to the top of Or it can have an angle degree as high as 30. All you need to do is measure how much to rise. He is also a certified marine technician and the author of a popular text on writing local history. Basically, there are three main ways to measure motor the propshaft below or above the pad. However, there may be times when a boater strays away from these recommendations. Trimming in, trimming down, and trimming out are all terms that a beginning boater should learn. relation to pad The outboard comes with mounting holes and brackets. As you can see, the measurement is about 2 1/2". You may wonder how deep your prop should be in the water. Then finally test your outboard, if the mount is perfect. your motor will be higher.) To break it down a bit more for you: Short shafts are 15-inches long. Small portable outboards ranging from 2 to 20 horsepower are usually sold only in short or long shaft versions. I run a 9.9 Mercury Bigfoot 20" shaft off the swim platform of my 89 Trophy 2160. If it measures 15" or with in a inch of that you will need a short shaft outboard. The clamp bracket on the latest Mercury Four-Stoke-model outboards has five mounting bolt holes spaced .75 inches apart. The cookie is used to store the user consent for the cookies in the category "Other.

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