The form of a boats transom varies depending on the manufacturer and model. Any owner seeking the last bit of speed from an outboard-powered boat should grab a yard stick. There is a simple test to see if your outboard motor is set at the best height. How high exactly do you have to raise the transom?-. Outboards designed for saltwater applications usually have longer shafts. As with anything, there are exceptions to the rule. Industry standards dictate that for short shaft engines the transom height should be 15. This, however, is not recommended for the beginning boater. You run the risk of possibly unsafe handling if you attempt to put a long shaft engine on a transom designed for a short shaft engine. If it measures 15" or with in a inch of that you will need a short shaft outboard. The height is approximately six inches higher than with a propeller. As summer approaches there will be more boaters taking to the water. I would also recommend finding your maximum horsepower rating which is located on the yellow coast guard tag towards the back of your boat. (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. Height Measurement: Recommended Shaft Length: 14" - 17.25" 15" Shaft (Short) 17.25" - 19.5" Varies by application 19.5" - 22.5" If the height of the boat transom is off it can cause major issues. 12 Small Fishing Boat Accessories to Buy Today. Some fishing boats can handle the motor being underwater. Raising the motor increases the speed of the boat while decreasing the effort needed to turn the boat. Make sure that you are measuring straight up, at a 90 degree angle to Picking the right shaft length for your outboard is an essential step in getting the best performance from your boat. Take your time and understand your boat and your entire transom. A2: Instead of changing to the short outboard shaft, you can try the Jack Plate first. If it measures between 17 and 22, you'll want to go with a long shaft motor. Smaller inflatables and dinghies needshort shaft motors, whilst bigger boats require long or, in some circumstances, extreme long shaft versions. It also cuts into speed and fuel efficiency. Well, raising the outboard motor can be an easy task for you. There is a simple test to see if your outboard motor is set at the best height. 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.) <> Ill also explain the difference between short and long shafts and how they vary by type of boat. Place the clubs bottom on the ground as though it were going to be used to strike a golf ball. In the photo above, we've measured from the motor bracket to the top of Your goal is to measure how the outboard will sit, so start from the clamping plate and follow the centerline of the hull. Cutting the transom down is the only legal method to utilize a short shaft engine on a tall transom. 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. 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. Then test the boat and adjust the height, if necessary . The shaft length for outboard motors has nothing to do with the water line. A transom saver, which can change the spacing between the lower unit and the trailer, negates some of the support. This could also effect your travelling capabilities on the boat trailer. 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. For most boaters this is a no brainer, but for the novice or inexperienced boater it may be a tougher question. Basically, there are three main ways to measure motor var BCData = {"csrf_token":"d7ecb6b56891bb66aee12dbc01a80162b3ed582c1acbe30f16fc9f1b2abc362f"}; However, there may be times when a boater strays away from these recommendations. And thats usually the case since the electric outboards are designed with larger and more efficient propeller that needs longer shaft. August 9/08). Typical motor lengths include the following. This is probably the worst case scenario out of the two. Here we will guide you in how to get the right boat transom height. Outboard shaft length plays a crucial role in the performance of your boat. For over five years he has worked as a newspaper reporter and historic researcher. var h = d.getElementsByTagName("head"), (In the case of the faster priceSelector: ".price--withoutTax, span.price.price--withTax", motor brackets The transom in a boat today is a place to hang your outboard motor. They operate as a planing surface, allowing your boat to climb to the top more quickly. All rights reserved. In addition, motor totes will not harm the finish of the lower unit. All you need to do is measure how much to rise. Higher mounting decisions should be left to the professionals. }, 100); Owners of bass boats, RIBs, or offshore fishing boats need to get this right. Here we will guide you in how to get the right boat transom height. Other uncategorized cookies are those that are being analyzed and have not been classified into a category as yet. Save my name, email, and website in this browser for the next time I comment. Also, the boat will be more likely to hit bottom or submerge objects such as rocks or logs. Long shafts are 20-inches long. Extra-long shafts are 25-inches long. straight edge from the center of the pad, but this time you're measuring Any questions? 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. Before we start measuring the outboard shaft length, lets get it clear about whats referring to when we talk about the outboard shaft length. As mentioned above, the operation of the propeller relies on the transom height. Simply start with the engine in idle, followed by, If you decide to make some custom adjustments we have the. You must be still in the blue about that matter. However, youll notice a little increase in drag and a decrease in top-end performance. 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. Increased RPM and additional horsepower feed the need for speed. The center is the point where your outboard motor is (ideally) located. Measure from there down to the top of the cavitation plate, also known as the anti-ventilation plate. It is possible that the motor could hang low while transporting on the boat trailer causing future boat repairs. The boat transom can be flat with zero degree angles. This will keep the prop in the water when the boat pitches in waves, or hobby-horses. The clamp bracket on the latest Mercury Four-Stoke-model outboards has five mounting bolt holes spaced .75 inches apart. It doesnt matter if you have a fiberglass boat, bay boat, big or small boat. Since the length of the shaft of your outboard is associated with the size boat, smaller engines will generally have shorter shafts. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. So you should just measure the height of the boat's transom from the center down to the lowest point of the hull, and compare transom height with the outboard shaft length numbers. Step 4. s.setAttribute("href", "https://cdn.paytomorrow.com/css/pt-mpe.min.css"); manufacturer will recommend the outboard height according to the bracket shape and length. of the motor off the transom function mpeInit() { Whether your on a pontoon boat, fishing boat, or speedboat boating is always one of the best times you can have. Now that you have a better understanding of boat transom heights its time to take out the ruler and get the perfect measurements. It is very versatile as it generally . A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. The transom angle is the vertical incline of the transom and is measured in degrees. Rebuilt - What You Need to Know, Lower Unit and Sterndrive Break-In Instructions. |. Mounting the outboard motor in accordance with the industry standards is important. So from there, I will try to help out by asking questions about your boat such as what type it is and the length. If you said you have a pontoon or a larger style boat such as a bass boat or speed boat, I would be pretty confident in saying it needs a long shaft. Outboard motors can be fitted to a variety of boats, so manufacturers have standardized their engines to go on virtually anything. The mounting height of an outboard motor can impact the speed and handling characteristics of the boat. It is extremely important that the boater understands the significance of the transom's height. Lubrication System Engine Oil Mixed Gasoline. If your outboard motor height. Transom Outboard Engine Position - YouTube 0:00 / 0:56 Transom Outboard Engine Position BOATING SCENE 763 subscribers 609 211K views 5 years ago www.boatingscene.com.au Sometimes when your. All rights reserved. Doing so, will put the propeller right below the boat. The prop will be in cleaner, harder water as it advances farther aft, making it more efficient. Boats that use longer outboard shafts include: 1 0 obj However, the shaft length for smaller boats could be long or short depending on its style, speed requirement, etc. function loadScript(script) { Using your existing control box and gauges will save you quite a bit of money in the end. All things considered, sticking with the industry standard is best for the beginner. gtag('js', new Date()); Mounting the outboard a little bit lower than the standard point could avoid the possible ventilation and slip on acceleration. What Types of Documents Can be Sent to your Kindle Library? center of the propshaft. 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. 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 transom is the rear wall of the boat where the outboard engine is mounted in the middle. If your boat planes, pay extra attention to getting the shaft length as close to perfect as possible. boats.com is part of the Boats Group Network. This was the height of my 225 Yamaha on my TR21 Mounting the motor lower on the boat transom can create excessive spray, increase case drag, reduce underwater clearance, and negatively impact faster boats. ), Al Shields With some boats I have a pretty good idea as to what length motor should be hung on them. If you decide to make some custom adjustments we have theexperience and know-howto make it happen. disregard the downward pointing "hooks" at the front of the The general guideline for longer shaft outboards is that the transom height should be at least 20 inches (50,8cm) above the waterline. If you have a question or need additional information,contact ustoday. To achieve this, the motor itself has to be attached at the correct height. I mean, who wants to purchase something as expensive as an outboard to only realize you bought the wrong one. To do so, you will want to measure at the exact center of the transom from the very top to the very bottom. 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). For slower boats, its less critical to. Always weigh the risks of making adjustments. To make the yard stick long enough to measure the length of all the clubs, tape the ruler to the top. He is a See When St. Peters Basketball Games Are Today! To measure the transom height, measure from the center on for transom (rear of the boat). AztH ^zv_ cT,E1K/rAB54| 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. Among them will be first-timers or those who have recently purchased their boats. The greater the number, the more the drive may sway (also called tuck under or negative trim). Some outboards have a serial number that tells you which shaft length to go for. straight edge on the top of the transom to "extend" it out primeApr: 12.99, See diagram below. 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. 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. maxAmount: 6500.0, 3 0 obj Your email address will not be published. One of the main concerns is causing the engine to overheat if not enough water reaches the engine to keep it cool. (Any measurement given as "off the transom" your motor will be higher.) 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. Also, how do you determine the length of an outboard transom? if (PayTomorrow) { Theyre also useful if the back of your boat has a non-standard measurement. 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. You'll need a short shaft outboard if it's 15 or less than an inch shorter. One of the main concerns is causing the engine to overheat if not enough water reaches the engine to keep it cool. As a result, the issue is whether my boat need a short shaft or long shaft motor. As summer approaches there will be more boaters taking to the water. 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. You 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. former editor at Boating Magazine and contributor to many national publications 7. 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). Or it can have an angle degree as high as 30. endobj 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). 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. No one wants to have issues with a new transom or boat repairs. Many boat transoms are modified to use a different length of outboard by using a bracket. to where the brackets were actually resting on the transom. relation to pad C Cheaptoon Cadet Joined Aug 4, 2010 Messages 28 Aug 24, 2010 #4 Re: Motor height on pontoon? If you are running a slower boat, the exact location of the ventilation plate is less important. Boaters who consider going with a higher mount can see increased speeds. Depending on the manufacturer, size names might change. Be sure to measure carefully and research thoroughly before diving in. 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). There are 2 steps to help get a relatively accurate figure. Tilt your motor until the bullet of the gearcase is Say the 20 shaft is a long shaft length for gas engines, but it is a short shaft length for electric outboard motors. s = d.createElement("link"); (function () { 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? Next, measure from your centerline to where the outboard will be mounted on each side. Smaller boats may use adjustable jack plates that can be changed to fit any 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. A: The answer varies by boat, but here are some rules of thumb for matching a short shaft outboard to your boat. of the "bullet" on your lower unit. For really big boats, the biggest and baddest six- or eight-cylinder outboards can have extra-extra long shafts up to 30 inches. Most transom savers can support up to a 150HP motor, which is sufficient for most regular boats. Propshaft in Engine Oil Type Genuine or Recommended 2str Engine Oil. Where Onboard a Boat is the Transom Located and More About Transom Heights A propeller operates based on the height of the transom. endobj MarinePartsMan.com also says that V6 bass-boat engines have a 20-inch shaft. I mean it is better to be safe than sorry, am I right? 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. This cookie is set by GDPR Cookie Consent plugin. #3. These cookies ensure basic functionalities and security features of the website, anonymously. You can use a longer shaft than recommended and your boat will work fine. Outboard Motor Shaft Length: How do I measure? 2 0 obj Knowing how this can affect the overall operation of the boat is a factor to be considered. Before we get started lets see what a boat transom is and what it does. Another important measurement is the transom angle. With a jack plate, you can mount it exactly where you want it. If we run into that scenario, I would still show you the different options of motors and go over pricing, but I would also ask you to hold off and do one thing before you pull the trigger. Increased RPM and additional horsepower feed the need for speed. It varies between different motors and boats. The first step is to determine the height of your boat's transom. 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). If the height of the boat transom is off it can cause major issues. Then, you can pick the right engine. Commonly, the transom angle ranges from 0-30 degrees, with the average transom angle set at 14 degrees. This is also known as the shaft length. % It can also improve the experience of driving a faster boat. s.setAttribute("src", script); s = d.createElement("script"); Other boats that need extra long shafts are: Read my other articles on outboard motors. If you went too long it would still work but it may lack in performance. 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? Remember, if you use a longer outboard shaft than you need you will be increasing your draft. Brackets are also handy for boats that do not have flat transoms, like canoe-stern sailboats or fan-tailed motor vessels. 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. The first order of business is to measure your boat for the ideal fit. Or measure from the main engine prop up to the water line? bassboat can be a bit confusing at times; hopefully this will help sort mpeSelector: ".pt-mpe", The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional". However, the motor should not be raised more than 5 inches above the standard position. A yardstick will help you determine if your outboard engine is at the right height. Take your time and understand your boat and your entire transom. 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. var addyd53b59933f6c3f2e8b59f1b4a6d41fa5 = 'info' + '@'; Place the point of a yardstick at the middle of the top of the boat transom. 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 transom to the bottom of the hull. So how to determine the outboard shaft length? You will also risk hitting bottom or submerge objects more frequently such as rocks or logs. The transom is the back of the boat where the motor is hung. displayPrimeOffers: true, 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. Again, make sure that you are measuring to the flat part of the brackets; <>/Metadata 127 0 R/ViewerPreferences 128 0 R>> Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. This cookie is set by GDPR Cookie Consent plugin. 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. %PDF-1.7 Beginning boaters should be aware of the boats measurements. MPW eBay Store - Thousands of New OEM Old Stock Parts! Read the following to get the optimal shaft length for outboard motors! Among them will be first-timers or those who have recently purchased their boats. Safely but briskly accelerate. I believe 20 to 21 inches is the optimum length for a lengthy shaft. 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. With it comes a lot of responsibility and new things to learn includingboat maintenanceand boat basics. The outboard comes with mounting holes and brackets. Measure straight down to the lowest point on the hull. This distance is very important to the performance of you boat. Check out the full chart of the Mercury outboard model code and its features. Here we look at the effects of standard, lower and higher mounting. Youll also want to pay attention when youre in shallow water because your prop will be lower than normal. It can also improve the experience of driving a faster boat. This will be the What are Apple Podcasts Subscriptions and Channels? 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.
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