However, the motor should not be raised more than 5 inches above the standard position. Another important measurement is the transom angle. And the rule of thumb is that you should keep the cavitation plate level with the bottom or keel of the boat. primeApr: 12.99, Outboard motors can be fitted to a variety of boats, so manufacturers have standardized their engines to go on virtually anything. If you decide to make adjustments, please consult a marine engine dealer about the boatdesign. To measure the transom height, measure from the center on for transom (rear of the boat). 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. h[0].appendChild(s); 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. The boater must also consider if the boat transom support is designed to bear the weight of a higher mount. However, youll notice a little increase in drag and a decrease in top-end performance. There are instances where a lower mount may be okay. Height Measurement: Recommended Shaft Length: 14" - 17.25" 15" Shaft (Short) 17.25" - 19.5" Varies by application 19.5" - 22.5" function loadScript(script) { To do so, take a measurement from the very top to the very bottom of the transom in the precise center. 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. There are a series of four to six holes at the top of the bracket, and the lower bolts actually fit into slots. 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. The transom is the "back wall" of your boat, the most rearward part of your hull. It doesnt matter if you have a fiberglass boat, bay boat, big or small boat. })(); Before we start measuring the outboard shaft length, lets get it clear about whats referring to when we talk about the outboard shaft length. boats.com is part of the Boats Group Network. "brackets". You need JavaScript enabled to view it. Typical motor lengths include the following. 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. On the downside, a higher mount can interfere with the boaters steering capabilities. Some fishing boats can handle the motor being underwater. Then finally test your outboard, if the mount is perfect. Check out some hot FAQs to help you get the proper outboard shaft lengths. Will Charpentier is a writer who specializes in boating and maritime subjects. 12 Small Fishing Boat Accessories to Buy Today. The boat transom can be flat with zero degree angles. How do you measure a transom on an outboard motor? Whether you already own a boat or looking for your first watercraft we are here to service your needs. The general guideline for longer shaft outboards is that the transom height should be at least 20 inches (50,8cm) above the waterline. Measure the area of the transom directly where the engine will be mounted. 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 cavitation plate is the horizontal surface of the lower unit immediately above the propeller. My family and I used it to fish, ski (yes, you can ski behind a pontoon boat), and cruise the lakes near our home. 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. 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. You dont have to be a mathematician to determine the correct boat transom angle. from the transom. 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. The transom is the boats flat vertical part at the back. <>
It is where the outboard is mounted, and some boat owners place the name of the boat. center of the propshaft. Its still smart to measure it yourself though, just in case, the design changed over the years. Plus, a low transom cut is an invitation for the water to flood the boat. It varies between different motors and boats. var BCData = {"csrf_token":"d7ecb6b56891bb66aee12dbc01a80162b3ed582c1acbe30f16fc9f1b2abc362f"}; The correct shaft length for your boat depends on a few factors. your motor will be higher.) Cavitation plates are used on the bottom components of boats to help them operate better. All things considered, sticking with the industry standard is best for the beginner. actually have the propshaft above the pad.). The height is approximately six inches higher than with a propeller. You need JavaScript enabled to view it. Eq*^?6R83e+j}UY.(M7k]~4g)g ~wmS{ O7t/o(W|X? Other boats that need long shafts are. August 9/08). trimming the motor out by one-half to full trim. Higher mounting decisions should be left to the professionals. A2: Instead of changing to the short outboard shaft, you can try the Jack Plate first. Boaters who consider going with a higher mount can see increased speeds. If the height of the boat transom is off it can cause major issues. If it measures 15" or with in a inch of that you will need a short shaft outboard. endobj
However, your boat will have slightly more drag which will reduce your maximum speed. Smaller inflatables and dinghies needshort shaft motors, whilst bigger boats require long or, in some circumstances, extreme long shaft versions. The Effects of Standard, Lower and Higher Mounting. These are vertically aligned so the boater can make adjustments. It is extremely important that the boater understands the significance of the transoms height. endobj
Triton. A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. So how to determine the outboard shaft length? Two years ago, I bought a Boston Whaler to fish off the coast. loadScript(ptScript); straight edge on the top of the transom to "extend" it out
Copyright 2017 Dealer Spike All Rights Reserved. Buying a boat can be an exciting purchase. All boats are different, and the motor manufacturers produce a variety of standard lengths. Take your time and understand your boat and your entire transom. It is possible that the motor could hang low while transporting on the boat trailer causing future boat repairs. 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). Boat transom angles play a pivotal role in the flexibility of the boats trimming abilities. Take a long straight edge, (long carpenter's level or long
Owners of bass boats, RIBs, or offshore fishing boats need to get this right. How the outboard will sit on the back of the boat depends on how the transom is designed. The transom is the flat vertical section at the rear of the boat. Use the mounting bracket on the motor to know where it will sit on the boat. 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. former editor at Boating Magazine and contributor to many national publications function gtag(){dataLayer.push(arguments);} Then test the boat and adjust the height, if necessary . Knowing how this can affect the overall operation of the boat is a factor to be considered. 1855 Alpine Avenue NWGrand Rapids, MI 49504This email address is being protected from spambots. Your at your local outboard dealer shopping for a new motor and the salesman hits you with the question, "short or long shaft?". 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 also might not be able to lift the outboard out of the water entirely for storage. Most of the time, adding a hydrofoil to an outboard improves performance. Many single-engine boats mount a smaller auxiliary motor for emergency use. The lowest point will likely be directly under your drain plug if youve got one. 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. Again, make sure that you are measuring to the flat part of the brackets;
s.setAttribute("type", "text/javascript"); Beyond motorboats designed for large outboards, you will see outboards hanging on the sterns of everything from small canoes to large cruising sailboats. If the propeller fails to ventilate, the motor is mounted to low. 1 0 obj
Later in the article is an image that shows you exactly where to measure. All rights reserved. h[0].appendChild(s); Small motors built for sailboats might come in a unique configuration with an extremely long shaft since these are mounted higher off the water. Check the literature about your model boat online, and you may be surprised to find that the number is published for you. Boats with more engine power and weight require longer shaft outboards for better balance. Chances are the boat was designed with a specific size of outboard in mind. No one wants to have issues with a new transom or boat repairs. var addy_textd53b59933f6c3f2e8b59f1b4a6d41fa5 = 'info' + '@' + 'vanssports' + '.' + 'com';document.getElementById('cloakd53b59933f6c3f2e8b59f1b4a6d41fa5').innerHTML += '
'+addy_textd53b59933f6c3f2e8b59f1b4a6d41fa5+'<\/a>'; Your goal is to measure how the outboard will sit, so start from the clamping plate and follow the centerline of the hull. You
Expectedly, when the transom angle is zero, it means it is flat. var path = 'hr' + 'ef' + '='; Here we will guide you in how to get the right boat transom height. You may wonder how deep your prop should be in the water. You'll need a short shaft outboard if it's 15 or less than an inch shorter. The boater must also consider if the boat transomsupport is designed to bear the weight of a higher mount. Measuring the shaft length can be done in various ways, but the most common way is by using a tape measure. A1: Broadly speaking, the outboard motor shaft length for pontoon boat, bass boat, or other larger boats should be long shaft. We also use third-party cookies that help us analyze and understand how you use this website. Here we will guide you in how to get the right boat transom height. I would ask you to go back and measure the transom of your boat. Having the cavitation plate too low will cause excess drag and reduced performance at high speeds. He is a The motor is what powers the boat so the two go hand-in-hand. maxAmount: 6500.0, (function (d) { brackets. C Cheaptoon Cadet Joined Aug 4, 2010 Messages 28 Aug 24, 2010 #4 Re: Motor height on pontoon? Whether your on a pontoon boat, fishing boat, or speedboat boating is always one of the best times you can have. The height of the boat transom dictates the size of the outboard motor. Commonly, the transom angle ranges from 0-30 degrees, with the average transom angle set at 14 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. So how to measure outboard shaft length? It can also improve the experience of driving a faster boat. 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). | Sitemap, The Marine Parts Warehouse Outboard Museum, OBR Powerhead / Shortblock Warranty Claim Form, Remanufactured vs. Among them will be first-timers or those who have recently purchased their boats. If youre looking for a bracket that can handle motors of up to 10/15 horsepower, go no further. As a yacht designer and boater, I prefer longer shafts. height (that I'm aware of); probably the most common is:
An inch or two probably wont make a big difference, but any more than that will lead to trouble. All things considered, sticking with the industry standard is best for the beginner. Thats a fairly simple list of symptoms, but if your motor is too low, youll probably notice at least one of them. Another important measurement is the transom angle. The transom angle is the vertical incline of the transom and is measured in degrees. 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. The pressure behind your hand dropped as you slid your hand back and forth through the water. Required fields are marked *. (function () { This allows the engine to idle without the flow of the exhaust being restricted. If you have a jackplate, you may have to get a bit creative in your
It also decreases the boats lift and increases the time it takes for the boat to reach plane. Each one has a totally different effect on the boats performance. It will ensure that the outboards trim will be effective, and it will save you gas too. 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.