For example, you can have the Mercury outboard shaft length by model code. If you have a small boat with a 15 to 17 inch aft transom, youll most likely need a short shaft outboard. This, however, is not recommended for the beginning boater. A reverse transom that sits too high can impact the propellers of the motor and motor bracket. How to Measure Transom Height For vessels with transom-mounted outboards, you can easily figure out which type of outboard you need to get. 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. You'll need a short shaft outboard if it's 15 or less than an inch shorter. Picking the right shaft length for your outboard is an essential step in getting the best performance from your boat. Required fields are marked *. This is measured by the propeller shaft being parallel to the vessels bottom. High powered boats usually only come in long and extra-long variants. clearInterval(interval); Gear Oil Quantity 195ml(6.6 Fl.oz.) storeDisplayName: "Marine Parts Warehouse", But in many cases, its a little more complicated than that alone. 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. 1 0 obj Take the center measurement from the top to the bottom of the hull. 12 Small Fishing Boat Accessories to Buy Today. In the case of a dinghy or johnboat, this point may be the top of the transom. This is a measurement that has been used for BassCats, I'm Add yours in the comment and Ill get back to you asap. As summer approaches there will be more boaters taking to the water. Smaller inflatables and dinghies needshort shaft motors, whilst bigger boats require long or, in some circumstances, extreme long shaft versions. Remanufactured 4 Cylinder 4-Stroke Cylinder Heads, Remanufactured 6 Cylinder 4-Stroke Cylinder Heads, Trim Relays, Trim Solenoids & Sending Units, Remanufactured V6 & V8 4-Stroke Cylinder Heads, Volvo Cobra SX Bearings and Bearing Carriers, Volvo Cobra SX Driveshaft, U-Joints & Parts, Volvo Cobra SX Transom Assembly & Bellows. Save my name, email, and website in this browser for the next time I comment. The dealer just hit you with the long or short shaft question and you have no clue as to what you need or even what he's talking about. (Any measurement given as "off the transom" The same is true for the newest, high-powered offshore fishing boats, where triple or quadruple motor setups are becoming more and more common. This is measured by the propeller shaft being parallel to the vessels bottom. However, there may be times when a boater strays away from these recommendations. not sure that it's still used. Bass boats, ski boats, or center cockpit vessels will want to double-check their measurements to get it just right. xmlHttp.open('POST', 'https://bes.gcp.data.bigcommerce.com/nobot'); (function (d) { function gtag(){dataLayer.push(arguments);} Keith Allen, a 1979 graduate of Valley City State College, has worked at a variety of jobs including computer operator, medical clinic manager, radio talk show host and potato sorter. 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. To achieve this, the motor itself has to be attached at the correct height. You may wonder how deep your prop should be in the water. If it measures anywhere from 17" to around 22", then your going to want to go with a long shaft motor. This is the dimension you'll need when selecting a width for your outboard motor's mounting bracket. The height of the boat transom dictates the size of the outboard motor. motor brackets Doing so, will put the propeller right below the boat. Offshore vessels are often equipped with a large mounting bracket so that the transom can be left at full height. Although the longer outboard shaft length can lead to lower speed and more drag, the boat can push a heavier load. Youll also want to pay attention when youre in shallow water because your prop will be lower than normal. This email address is being protected from spambots. I also love helping others, which is why I created this website. Generally, short shaft outboards are 15 inches, long shaft outboards are 20 inches, and extra-long outboards are 25 inches. Ten years ago I bought my first boat. You reply, "Im not sure, I think its a long". Eq*^?6R83e+j}UY.(M7k]~4g)g ~wmS{ O7t/o(W|X? #3. This is somewhat similar to #2, in that you are again measuring with a brackets. 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. But, how do you measure it? 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. 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. Whether you already own a boat or looking for your first watercraft we are here to service your needs. To do so, you will want to measure at the exact center of the transom from the very top to the very bottom. endobj jackplate to a point level with the top of the transom. A yardstick will help you determine if your outboard engine is at the right height. His works have appeared in regional newspapers in North Dakota and in "North Dakota Horizons" and "Cowboys and Indians" magazines. When the boat transom is too low, the motor could end up underwater. Boaters who consider going with a higher mount can see increased speeds. Re: Dinghy with a long shaft motor? The transom is the back of the boat where the motor is hung. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. The Effects of Standard, Lower and Higher Mounting. Two years ago, I bought a Boston Whaler to fish off the coast. The amount of degrees the transom leans back from vertical is known as the transom angle. 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. In lower mounting, the engine is set lower than the recommended standard. Each one has a totally different effect on the boats performance. <> There are a series of four to six holes at the top of the bracket, and the lower bolts actually fit into slots. Pretty easy to figure out but like I said its crucial to pairing a motor with a boat. s = d.createElement("link"); If you are running a slower boat, the exact location of the ventilation plate is less important. Remember, if you use a longer outboard shaft than you need you will be increasing your draft. Lubrication System Engine Oil Mixed Gasoline. I believe 20 to 21 inches is the optimum length for a lengthy shaft. This also means it can affect the safety of the boat. It is extremely important that the boater understands the significance of the transom's height. Knowing how this can affect the overall operation of the boat is a factor to be considered. maxAmount: 6500.0, With the outboard shaft length too long, meaning the prop is too deep in the water, the engine wont be as efficient, and the fuel burn is high. Typical motor lengths include the following. Anything bigger than that your obviously going to need an extra long shaft. 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. By clicking Accept, you consent to the use of ALL the cookies. Owners of bass boats, RIBs, or offshore fishing boats need to get this right. Since the length of the shaft of your outboard is associated with the size boat, smaller engines will generally have shorter shafts. Follow Westshore Marine & Leisure on Twitter! The transom is the "back wall" of your boat, the most rearward part of your hull. The transom angle is the vertical incline of the transom and is measured in degrees. 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. C Cheaptoon Cadet Joined Aug 4, 2010 Messages 28 Aug 24, 2010 #4 Re: Motor height on pontoon? var ptScript = "https://cdn.paytomorrow.com/js/pt-mpe.min.js"; <>/ExtGState<>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 595.2 841.8] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> Not to measure boat speed, but to gauge the mounting height of the outboard motor on the boat transom. They keep water out of your prop and increase water pressure in the system. To do so, take a measurement from the very top to the very bottom of the transom in the precise center. since 1986. measuring; you may have to "extend" the flat part of the The outboard comes with mounting holes and brackets. While this is the case there is certain saltwater motors that are extra extra long at 30 and 35 shaft. 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. Doing this can have adverse effects. However, there may be times when a boater strays away from these recommendations. You can find your Mercury outboard model code on an ID plate or sticker. These cookies ensure basic functionalities and security features of the website, anonymously. Other boats that need extra long shafts are: Read my other articles on outboard motors. Oftentimes you will want to adjust the outboard shaft length in order to improve the boat performance such as speed. Raising the motor increases the speed of the boat while decreasing the effort needed to turn the boat. Measure from the top of the straight edge to the center of the front All you need to do is measure how much to rise. Boat hulls are designed in three basic types that range from slow displacement and semi-displacement hulls to the fastest planing hulls. Say the 20 shaft is a long shaft length for gas engines, but it is a short shaft length for electric outboard motors. boats.com is part of the Boats Group Network. Well, raising the outboard motor can be an easy task for you. On the downside, a higher mount can interfere with the boaters steering capabilities. Outboards designed for saltwater applications usually have longer shafts. actually have the propshaft above the pad.). You need JavaScript enabled to view it. 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. Recommended Engine Oil 2-Stroke Outboard Motor Oil. I show you how to consistently measure your prop to pad height. We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. Here we look at the effects of standard, lower and higher mounting. As a dealer I run into this situation from time to time, which is fine but getting the right length outboard for your boat is crucial. 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. maxTerm: 36, This is also known as the shaft length. These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc. Your email address will not be published. 2019s List of the Best Recreational Pontoon Boats for Sale. Smaller 12-14 foot boats can require either a short or long shaft outboard depending on the style of the boat and the brand. Over time, Boating Hub has grown into a resource for boating enthusiasts around world. 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. The motor is what powers the boat so the two go hand-in-hand. And thats usually the case since the electric outboards are designed with larger and more efficient propeller that needs longer shaft. One of the factors in determining the height of the outboard is the placement of the exhaust port on the lower unit of the outboard engine. The correct shaft length for your boat depends on a few factors. Depending on the manufacturer, size names might change. 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. hulls, such as Allisons, Bullets, Strokers, etc., this measurement could This was the height of my 225 Yamaha on my TR21 Gear case sits just below or at the hull depth due to the deep v. (function () { Follow Westshore Marine & Leisure on Wordpress! })(); Other boats that need long shafts are. For really big boats, the biggest and baddest six- or eight-cylinder outboards can have extra-extra long shafts up to 30 inches. displayMicroOffers: false, s.setAttribute("href", "https://cdn.paytomorrow.com/css/pt-mpe.min.css"); This alone can outweigh the negatives when deciding to adjust the mount upwards. In the second photo, we've measure down from the top of the Detwiler var BCData = {"csrf_token":"d7ecb6b56891bb66aee12dbc01a80162b3ed582c1acbe30f16fc9f1b2abc362f"}; The cookie is used to store the user consent for the cookies in the category "Analytics". Trimming in, trimming down, and trimming out are all terms that a beginning boater should learn. 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. Some boats are equipped with transom-hung outboards while others have a bracket. If you decide to make some custom adjustments we have theexperience and know-howto make it happen. The outboard comes with mounting holes and brackets. This alone can outweigh the negatives when deciding to adjust the mount upwards. the aluminum plate on top of the transom), to the bottom of the motor document.getElementById('cloakd53b59933f6c3f2e8b59f1b4a6d41fa5').innerHTML = ''; want to measure from the transom to the flat part of this bracket, Determining Your Boat Transom Angle The transom angle - commonly measured in degrees - is the transom's vertical inclination. 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. This measurement would be the inches of However, your boat will have slightly more drag which will reduce your maximum speed. Raising an outboard higher on the transom can reduce drag and raise top speed. Some fishing boats can handle the motor being underwater. It doesnt matter if you have a fiberglass boat, bay boat, big or small boat. steel ruler, etc. Get the latest updates on new products and upcoming sales, 2023 Marine Parts Warehouse Incorporated It will ensure that the outboards trim will be effective, and it will save you gas too. Mounting the outboard a little bit lower than the standard point could avoid the possible ventilation and slip on acceleration. Simply start with the engine in idle, followed bytrimming the motor out by one-half to full trim. This allows the engine to idle without the flow of the exhaust being restricted. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. 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. 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. Then open up the clamp bucket. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. In addition, motor totes will not harm the finish of the lower unit. These cookies will be stored in your browser only with your consent. Extra-extra long shafts are 30-inches long. the propshaft below or above the pad. All boats are different, and the motor manufacturers produce a variety of standard lengths. The cookie is used to store the user consent for the cookies in the category "Performance". Outboard motors can be fitted to a variety of boats, so manufacturers have standardized their engines to go on virtually anything. This cookie is set by GDPR Cookie Consent plugin. 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. 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? Step 2 requires the propeller's radius (check the user manual and then the technical drawing). addyd53b59933f6c3f2e8b59f1b4a6d41fa5 = addyd53b59933f6c3f2e8b59f1b4a6d41fa5 + 'vanssports' + '.' + 'com'; Read the following to get the optimal shaft length for outboard motors! Then, you can pick the right engine. :$I>M W$h"%U_yzIb?]NHg_G|r@nX eTf."SQ Youll need a short shaft outboard if its 15 or less than an inch shorter. Basically, there are three main ways to measure motor If you said something smaller than that, thats where it can get tricky. I hope this helps someone out in their search for a new or newer outboard this season. It can also improve the experience of driving a faster boat. Triton. bassboat can be a bit confusing at times; hopefully this will help sort And the rule of thumb is that you should keep the cavitation plate level with the bottom or keel of the boat. To measure the transom height, measure from the center on for transom (rear of the boat). For slower boats, its less critical to. Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. The propellers will also have trouble reaching the water. 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). See diagram below. There are 2 steps to help get a relatively accurate figure. This restriction includes most fishing boats and longer sailboats. All things considered, sticking with the industry standard is best for the beginner. You must be still in the blue about that matter. If you have a jackplate, you may have to get a bit creative in your There are instances where a lower mount may be okay. Mounting the motor lower on the boat transom can create excessive spray, increase case drag, reduce underwater clearance, and negatively impact faster boats. ), and place it on the bottom of the pad in the center. The boater must also consider if the boat transomsupport is designed to bear the weight of a higher mount. Propshaft in 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. August 9/08). Generally, the anti-ventilation plate on most engines is aligned with the bottom of the vessel. Brackets are also handy for boats that do not have flat transoms, like canoe-stern sailboats or fan-tailed motor vessels. <> Take a long straight edge, (long carpenter's level or long Other factors to consider when determining the mounting height of an outboard are related to performance. See When St. Peters Basketball Games Are Today! boats.com, 1221 Brickell Avenue, 23rd Floor, Miami, FL 33131, USA. Boat Transom Heights The Beginners Guide, Buying a boat can be an exciting purchase. As with anything, there are exceptions to the rule. This transom saver will support the weight of your outboard throughout your road travel, steadily bracing it against the trailer frame to relieve your transom of the weight and impact from consistent bouncing. If the height of the boat transom is off it can cause major issues. Place the rulers end on the ground behind the club and let the club to rest on top of it. Take your time and understand your boat and your entire transom. What is the Virtual Sundance Film Festival? 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. xmlHttp.setRequestHeader('Content-Type', 'application/json'); To break it down a bit more for you: Short shafts are 15-inches long. relation to pad This distance is very important to the performance of you boat. Many single-engine boats mount a smaller auxiliary motor for emergency use. <>/Metadata 127 0 R/ViewerPreferences 128 0 R>> window.dataLayer = window.dataLayer || []; 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. The engine must be linked to the transom at the proper height for a propeller to best meet specific boating demands. But opting out of some of these cookies may affect your browsing experience. Repowering your boat is one of the most expensive upgrades you can make. Boaters who consider going with a higher mount can see increased speeds. The transom is the rear wall of the boat where the outboard engine is mounted in the middle. Pad to bottom of mpeSelector: ".pt-mpe", In step 3, add another 10 cm (4") to the previous calculation in order to develop the ideal shaft length. Most of the time, adding a hydrofoil to an outboard improves performance. *The Factors indicates the adjustment affected by on your boat type, the outboard working environment, and the transom distance as discussed above. Any questions? 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. Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. primeApr: 12.99, maxMicroAmount: 0.0, (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. (Putting a 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). This could also affect your travelling capabilities on the boat trailer. If it measures 15" or with in a inch of that you will need a short shaft outboard. Then test the boat and adjust the height, if necessary . A: The answer varies by boat, but here are some rules of thumb for matching a short shaft outboard to your boat. Commonly, the transom angle ranges from 0-30 degrees, with the average transom angle set at 14 degrees. One of the main concerns is causing the engine to overheat if not enough water reaches the engine to keep it cool. 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. The height of the boat transom dictates the size of the outboard motor. (3) Move horizontally across the chart until you hit the graph curve. function loadScript(script) { The pros and cons of properly . Engine Oil Type Genuine or Recommended 2str Engine Oil. He is a These two measurements will give you the length of the shaft you need. 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}'); It doesnt matter if you have a fiberglass boat, bay boat, big or small boat. I would ask you to go back and measure the transom of your boat. The collapsing bubbles are loaded with extremely low-pressure water vapor, which causes damage to a variety of surfaces as they collapse. 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. Your email address will not be published. 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. He is also a certified marine technician and the author of a popular text on writing local history. Also, how do you determine the length of an outboard transom? #2. Your goal is to measure how the outboard will sit, so start from the clamping plate and follow the centerline of the hull. Boat transom angles play a pivotal role in the flexibility of the boats trimming abilities. Picking the right shaft length is mostly a factor of the transom height or the back of the boat. When trimming your motor, they provide you a greater bow response. var addyd53b59933f6c3f2e8b59f1b4a6d41fa5 = 'info' + '@'; The first order of business is to measure your boat for the ideal fit. Another important measurement is the transom angle. from the transom. Place the point of a yardstick at the middle of the top of the boat transom. This placement is not only recommended but it will give you the best performance compared to something that is too long or too short. Then finally test your outboard, if the mount is perfect. 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. 2 0 obj Knowing how this can affect the overall operation of the boat is a factor to be considered. For most boaters this is a no brainer, but for the novice or inexperienced boater it may be a tougher question. It is possible that the motor could hang low while transporting on the boat trailer causing future boat repairs. Plus, a low transom cut is an invitation for the water to flood the boat. 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. If you went too long it would still work but it may lack in performance. This exhaust port should be about 1 inch above the water line when the boat is idling. The cookie is used to store the user consent for the cookies in the category "Other. This measurement is primarily designed for single motor propulsion. The clamp bracket on the latest Mercury Four-Stoke-model outboards has five mounting bolt holes spaced .75 inches apart. This cookie is set by GDPR Cookie Consent plugin. The prop will be in cleaner, harder water as it advances farther aft, making it more efficient. Outboard Motor Shaft Length: How do I measure? Where Onboard a Boat is the Transom Located and More About Transom Heights A propeller operates based on the height of the transom. Should I take the raft onto the water and measure the exact distance from the top of the transom to the water line? What types of boat need an extra long shaft? stream 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. var prefix = 'ma' + 'il' + 'to'; Happy boating! Whats the best height for my boat motor? How the outboard will sit on the back of the boat depends on how the transom is designed. This provides seaworthiness and offers maximum protection from large seas. Cutting the transom down is the only legal method to utilize a short shaft engine on a tall transom. Why wont Touch ID be under the screen in the iPhone 15 and iPhone 16? Ill also explain the difference between short and long shafts and how they vary by type of boat. The clamp bracket is designed so that the engine's mounting height on the transom can be adjusted higher than standard. To achieve 35 mph with a 6 hp engine, the total weight is 135 lbs (boat motor fuel passengers). If the propeller fails to ventilate, the motor is mounted to low. These allow the mounting of a standard length outboard behind the transom. Higher mounting decisions should be left to the professionals. All rights reserved. If it measures anywhere from 17" to around 22", then your going to want to go with a long shaft motor. You dont have to be a mathematician to determine the correct boat transomangle. If you are looking to repower, they may be able to offer some sage advice. These cookies track visitors across websites and collect information to provide customized ads. 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. This cookie is set by GDPR Cookie Consent plugin. center of the propshaft. The transom in a boat today is a place to hang your outboard motor. Hold the tape on the top, center of the taffrail and measure straight down to the point, usually a sharp angle, where the transom joins the bottom of the boat. As mentioned above, the operation of the propeller relies on the transom height. We also use third-party cookies that help us analyze and understand how you use this website. if (PayTomorrow) { https://www.bornagainboating.com/Get Your Born Again Boating Clothing!
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how to measure transom height for outboard motor