Beefier jack plates can be fitted should a boater be looking to mount an outboard with a shorter shaft than their transom demands. The transom is the flat vertical section at the rear of the boat. In lower mounting, the engine is set lower than the recommended standard. When the boat transom is too low, the motor could end up underwater. Happy boating! Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. Repowering your boat is one of the most expensive upgrades you can make. It is where the outboard is mounted, and some boat owners place the name of the boat. For example, you can have the Mercury outboard shaft length by model code. Actual shaft length is 21.5" on those. Its important to note that manufacturers call their models different things. It can also improve the experience of driving a faster boat. 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. <>/ExtGState<>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 595.2 841.8] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> var interval = setInterval(function () { There are also specialty motor shaft lengths. Other factors to consider when determining the mounting height of an outboard are related to performance. His works have appeared in regional newspapers in North Dakota and in "North Dakota Horizons" and "Cowboys and Indians" magazines. The cavitation plate is the horizontal surface of the lower unit immediately above the propeller. Brackets are also handy for boats that do not have flat transoms, like canoe-stern sailboats or fan-tailed motor vessels. The lowest point will likely be directly under your drain plug if youve got one. If the propeller fails to ventilate, the motor is mounted to low. However, there may be times when a boater strays away from these recommendations. The height is approximately six inches higher than with a propeller. Is my outboard long or short shaft? It is possible that the motor could hang low while transporting on the boat trailer causing future boat repairs. }) } }); })(document); Cutting the transom down is the only legal method to utilize a short shaft engine on a tall transom. Tightening Torque for Engine. You must be still in the blue about that matter. To break it down a bit more for you: Short shafts are 15-inches long. Read the following to get the optimal shaft length for outboard motors! #1: Height Thats a fairly simple list of symptoms, but if your motor is too low, youll probably notice at least one of them. On the downside, a higher mount can interfere with the boaters steering capabilities. I mean, who wants to purchase something as expensive as an outboard to only realize you bought the wrong one. Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. You also have the option to opt-out of these cookies. This also means it can affect the safety of the boat. Cavitation plates are used on the bottom components of boats to help them operate better. This measurement is primarily designed for single motor propulsion. bracket forward with a straight edge to where you can then measure up If it measures between 17 and 22, youll want to go with a long shaft motor. 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. (616) 364-0666, On all contiguous US part orders over $100. motor brackets Tilt your motor until the bullet of the gearcase is The average transom angle is around 14 degrees. *The Factors indicates the adjustment affected by on your boat type, the outboard working environment, and the transom distance as discussed above. Also, the boat will be more likely to hit bottom or submerge objects such as rocks or logs. Actually there is no designated letter for short shaft. 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. Remember, if you use a longer outboard shaft than you need you will be increasing your draft. 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. Industry standards dictate that for short shaft engines the transom height should be 15. (In the case of the faster Simply start with the engine in idle, followed by, If you decide to make some custom adjustments we have the. To sum up, there is a simple calculator of the shaft length for outboard motors: Outboard Shaft Length = Transom Height +/- Factors. 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. Your email address will not be published. Having the cavitation plate too low will cause excess drag and reduced performance at high speeds. The how to measure the shaft length of an outboard motor is a question that many people have asked. Each one has a totally different effect on the boats performance. 4 0 obj 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. The transom angle is the vertical incline of the transom and is measured in degrees. Commonly, the transom angle ranges from 0-30 degrees, with the average transom angle set at 14 degrees. 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? Outboards designed for saltwater applications usually have longer shafts. function mpeInit() { Measure from the top of the transom to the bottom of the hull. This will be the As with anything, there are exceptions to the rule. s.setAttribute("type", "text/javascript"); Your email address will not be published. The motor is what powers the boat so the two go hand-in-hand. For vessels with transom-mounted outboards, you can easily figure out which type of outboard you need to get. The prop will be in cleaner, harder water as it advances farther aft, making it more efficient. This website uses cookies to improve your experience while you navigate through the website. While this is the case there is certain saltwater motors that are extra extra long at 30. 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. Generally, short shaft outboards are 15 inches, long shaft outboards are 20 inches, and extra-long outboards are 25 inches. publicId: "32bf3437d1346295e03ebcf545f9c839", 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. The general guideline for longer shaft outboards is that the transom height should be at least 20 inches (50,8cm) above the waterline. You'll need a short shaft outboard if it's 15 or less than an inch shorter. document.getElementById('cloakd53b59933f6c3f2e8b59f1b4a6d41fa5').innerHTML = ''; Buying a boat can be an exciting purchase. How Transom Height Is Measured This cookie is set by GDPR Cookie Consent plugin. Generally, the anti-ventilation plate on most engines is aligned with the bottom of the vessel. 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. 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. Doing this can have adverse effects. What types of boat need an extra long shaft? When mounting the engine, you want the cavitation plate to be 1 above the boat bottom for every 12 away from the transom. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. Add the two measurements and you get 6 1/2". The propellers will also have trouble reaching the water. 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. Triton. You reply, "Im not sure, I think its a long". The cookie is used to store the user consent for the cookies in the category "Other. The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional". Raising an outboard higher on the transom can reduce drag and raise top speed. Basically, there are three main ways to measure motor Step 2 requires the propeller's radius (check the user manual and then the technical drawing). If your boat planes, pay extra attention to getting the shaft length as close to perfect as possible. One of the main concerns is causing the engine to overheat if not enough water reaches the engine to keep it cool. To do so, you will want to measure at the exact center of the transom from the very top to the very bottom. As with anything, there are exceptions to the rule. A yardstick will help you determine if your outboard engine is at the right height. 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. Allowing the propeller to pull water from underneath and push it out behind the boat. For really big boats, the biggest and baddest six- or eight-cylinder outboards can have extra-extra long shafts up to 30 inches. The transom in a boat today is a place to hang your outboard motor. and I'll explain it better, (or point you to someone that can help. Measure straight down to the lowest point on the hull. If it measures 15" or with in a inch of that you will need a short shaft outboard. Step 2: Three Variables to Consider Expectedly, when the transom angle is zero, it means it is flat. 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. Pretty easy to figure out but like I said its crucial to pairing a motor with a boat. Like Westshore Marine & Leisure on Facebook! You may wonder how deep your prop should be in the water. C Cheaptoon Cadet Joined Aug 4, 2010 Messages 28 Aug 24, 2010 #4 Re: Motor height on pontoon? enableMoreInfoLink: true, e-mail The faster your boat, the more critical it is to get the sizing just right. This cookie is set by GDPR Cookie Consent plugin. This alone can outweigh the negatives when deciding to adjust the mount upwards. Measure from the top of the straight edge to the center of the front There is a simple test to see if your outboard motor is set at the best height. There is a simple test to see if your outboard motor is set at the best height. var xmlHttp = new XMLHttpRequest(); To do so, take a measurement from the very top to the very bottom of the transom in the precise center. 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. If it measures 15" or with in a inch of that you will need a short shaft outboard. displayMicroOffers: false, Youll also want to pay attention when youre in shallow water because your prop will be lower than normal. Lastly, knowing the year of your motor and what style of controls you have (side mount, concealed side mount, or binnacle) is also a plus because it will tell the dealer if your current controls are compatible with the motor you are purchasing. Take a long straight edge, (long carpenter's level or long % Pad to bottom of Boat Transom Heights The Beginners Guide, Buying a boat can be an exciting purchase. To do so, measure from the stern (back) of the boat to the midpoint of the hull on both sides. Should I take the raft onto the water and measure the exact distance from the top of the transom to the water line? Required fields are marked *. There are 2 steps to help get a relatively accurate figure. 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. Knowing how this can affect the overall operation of the boat is a factor to be considered. var path = 'hr' + 'ef' + '='; 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). August 9/08). 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. 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? To achieve this, the motor itself has to be attached at the correct height. Necessary cookies are absolutely essential for the website to function properly. 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. Depending on the manufacturer, size names might change. Take your time and understand your boat and your entire transom. It will ensure that the outboards trim will be effective, and it will save you gas too. Gear Oil Quantity 195ml(6.6 Fl.oz.) If you are running a twin-engine setup, then measure the same distance from each clamping plate to the bottom of the hull. The motor length corresponds to the transom height of the boat, measured from the keel to gunwale at the transom. The transom is the "back wall" of your boat, the most rearward part of your hull. In the past, though, it housed the officers and captain of 17th, 18th and 19th century sailing ships. It does not store any personal data. your motor will be higher.) The mounting height of an outboard motor can impact the speed and handling characteristics of the boat. 7. 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. This, however, is not recommended for the beginning boater. 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. var BCData = {"csrf_token":"d7ecb6b56891bb66aee12dbc01a80162b3ed582c1acbe30f16fc9f1b2abc362f"}; var h = d.getElementsByTagName("head"), When fighting waves from the stern, a 20-inch transom is considerably safer. The pressure behind your hand dropped as you slid your hand back and forth through the water. Not to measure boat speed, but to gauge the mounting height of the outboard motor on the boat transom. Engine Oil Type Genuine or Recommended 2str Engine Oil. This would not be a good thing. Most transom savers can support up to a 150HP motor, which is sufficient for most regular boats. Then adjust the motor in a higher hole with a flat head screwdriver. You need JavaScript enabled to view it. I would ask you to go back and measure the transom of your boat. Doing this can have adverse effects. In the case of a dinghy or johnboat, this point may be the top of the transom. No one wants to have issues with a new transom or boat repairs. 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. Get the latest updates on new products and upcoming sales, 2023 Marine Parts Warehouse Incorporated I run a 9.9 Mercury Bigfoot 20" shaft off the swim platform of my 89 Trophy 2160. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. ), and place it on the bottom of the pad in the center. 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. With a jack plate, you can mount it exactly where you want it. 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. Lubrication System Engine Oil Mixed Gasoline. What is the Virtual Sundance Film Festival? With such an important, long-term, and expensive upgrade, its never a bad idea to double-check. Then test the boat and adjust the height, if necessary . Outboard motors can be fitted to a variety of boats, so manufacturers have standardized their engines to go on virtually anything. This placement is not only recommended but it will give you the best performance compared to something that is too long or too short. 2 0 obj } would be more accurate.) The first order of business is to measure your boat for the ideal fit. 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 transom is the back of the boat where the motor is hung. This will ensure the best performance. A big NO. MPW eBay Store - Thousands of New OEM Old Stock Parts! For most boaters this is a no brainer, but for the novice or inexperienced boater it may be a tougher question. Well, raising the outboard motor can be an easy task for you. You can use a longer shaft than recommended and your boat will work fine. Boat hulls are designed in three basic types that range from slow displacement and semi-displacement hulls to the fastest planing hulls. However, youll notice a little increase in drag and a decrease in top-end performance. Another important measurement is the transom angle. To measure your outboard motor shaft length, measure from the bottom of the mounting bracket where it rests on the transom to the top of the cavitation plate, this is the horizontal surface of the lower unit immediately above the propeller. He is a jackplate to a point level with the top of the transom. A transom saver, which can change the spacing between the lower unit and the trailer, negates some of the support. The propellers will also have trouble reaching the water. It is extremely important that the boater understands the significance of the transoms height. All things considered, sticking with the industry standard is best for the beginner. It varies between different motors and boats. boats.com is part of the Boats Group Network. And thats usually the case since the electric outboards are designed with larger and more efficient propeller that needs longer shaft. Amazon has plate extensions to allow adjustments without buying a new motor: T-H Marine Jack Plate Extension. endobj 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. Add yours in the comment and Ill get back to you asap. out the confusion. Height Measurement: Recommended Shaft Length: 14" - 17.25" 15" Shaft (Short) 17.25" - 19.5" Varies by application 19.5" - 22.5" logoColor: "original", Having the cavitation plate a bit lower than the transom is preferable to having it too high. 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. If you are looking to repower, they may be able to offer some sage advice. Measuring the shaft length can be done in various ways, but the most common way is by using a tape measure. of the "bullet" on your lower unit. Buying a boat can be an exciting purchase. 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. Thats it. They operate as a planing surface, allowing your boat to climb to the top more quickly. 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. Whether you already own a boat or looking for your first watercraft we are here to service your needs. 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. 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. But, how do you measure it? The center is the point where your outboard motor is (ideally) located. If mounting directly to a boat transom: Measure from the top of the transom down to the bottom of the hull or keel (lowest point). At least if its too long you can raise the motor or "build up" your transom. want to measure from the transom to the flat part of this bracket, 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. 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. All rights reserved. |. MarinePartsMan.com also says that V6 bass-boat engines have a 20-inch shaft. Here we look at the effects of standard, lower and higher mounting. 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. 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. The brackets can add 1 inch to the overall mounting height of the outboard. Assistant Measuring tape Grease pencil 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. } It doesnt matter if you have a fiberglass boat, bay boat, big or small boat. Doing so, will put the propeller right below the boat. 1 0 obj Follow Westshore Marine & Leisure on Twitter! You also might not be able to lift the outboard out of the water entirely for storage. It is possible that the motor could hang low while transporting on the boat trailer causing future boat repairs. 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. I hope this helps someone out in their search for a new or newer outboard this season. This will keep the prop in the water when the boat pitches in waves, or hobby-horses. <> bassboat can be a bit confusing at times; hopefully this will help sort Trimming in, trimming down, and trimming out are all terms that a beginning boater should learn. What the relationship to the pontoons is, I couldn't say. 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}'); manufacturer will recommend the outboard height according to the bracket shape and length. Other boats that need extra long shafts are: Read my other articles on outboard motors. Owners of bass boats, RIBs, or offshore fishing boats need to get this right. Beginning boaters should be aware of the boats measurements. 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. On the downside, a higher mount can interfere with the boaters steering capabilities. xmlHttp.setRequestHeader('Content-Type', 'application/json'); (We wont go into name-calling here, but the actual term for the cavitation plate is an anti-ventilation plate.) The outboard comes with mounting holes and brackets. Measure the area of the transom directly where the engine will be mounted. Outboard Motor Shaft Length: How do I measure? Simply start with the engine in idle, followed by trimming the motor out by one-half to full trim. Use the mounting bracket on the motor to know where it will sit on the boat. Its where the outboard motor is attached, and its also where some boat owners put the boats name. Youll need a short shaft outboard if its 15 or less than an inch shorter. 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. 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). This restriction includes most fishing boats and longer sailboats. relation to pad since 1986. This is probably the worst case scenario out of the two. These cookies ensure basic functionalities and security features of the website, anonymously. 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). Many single-engine boats mount a smaller auxiliary motor for emergency use. As a dealer I don't really like hearing this because there is a chance it could go either way and you have to get it right. In the case of a larger offshore boat, it may be to the top of a cutout on the . primeApr: 12.99, The engine must be linked to the transom at the proper height for a propeller to best meet specific boating demands. See diagram below. To do so, you will want to measure at the exact center of the transom from the very top to the very bottom.
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