The amount of degrees the transom leans back from vertical is known as the transom angle. Other factors to consider when determining the mounting height of an outboard are related to performance. Engine height with stepped hull at transom - before I screw things up (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. will be to the flat part; if you measure to the bottom of the brackets Take your time and understand your boat and your entire transom. 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. If you decide to make adjustments, please consult a marine engine dealer about the boat design. With some boats I have a pretty good idea as to what length motor should be hung on them. These cookies will be stored in your browser only with your consent. However, with the outboard shaft length too short, meaning the prop is too close to the surface, the engine is likely to ventilate and therefore slip on acceleration or lose power. 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. This measurement was approximately 4". your motor will be higher.) Step 2: After you get the transom height, add the radius of the propeller (check the user manual, and then technical drawing for the number) to calculate the minimum shaft length needed to make it work. 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 general guideline for longer shaft outboards is that the transom height should be at least 20 inches (50,8cm) above the waterline. 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. All rights reserved. not sure that it's still used. 2 0 obj function mpeInit() { Attention: Remember to measure the outboard shaft length straight up and down instead of measuring along the transom. However, the shaft length for smaller boats could be long or short depending on its style, speed requirement, etc. Check out the Westshore Marine & Leisure Youtube page! 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. up to the bottom of the motor brackets, (as in #1). It also cuts into speed and fuel efficiency. Take a long straight edge, (long carpenter's level or long Then test the boat and adjust the height, if necessary . For boats equipped with a bracket, calculate the same measurement but based on the bracket and not the transom. straight edge from the center of the pad, but this time you're measuring Be sure to measure carefully and research thoroughly before diving in. 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. How to Measure Shaft Length on Outboard Motor? - TrollinMotorsGuide Beyond motorboats designed for large outboards, you will see outboards hanging on the sterns of everything from small canoes to large cruising sailboats. These two measurements will give you the length of the shaft you need. Then adjust the motor in a higher hole with a flat head screwdriver. We also use third-party cookies that help us analyze and understand how you use this website. For really big boats, the biggest and baddest six- or eight-cylinder outboards can have extra-extra long shafts up to 30 inches. Safely but briskly accelerate. The transom is the boats flat vertical part at the back. Move the bracket as close to the center of the transom as possible while still maintaining clearance to allow the main outboard or rudder to reach its full range of motion without contacting the kicker motor. Mounting the outboard motor in accordance with the industry standards is important. There are instances where a lower mount may be okay. Always weigh the risks of making adjustments. While this is the case there is certain saltwater motors that are extra extra long at 30 and 35 shaft. straight edge on the top of the transom to "extend" it out Buying a boat can be an exciting purchase. C Cheaptoon Cadet Joined Aug 4, 2010 Messages 28 Aug 24, 2010 #4 Re: Motor height on pontoon? the aluminum plate on top of the transom), to the bottom of the motor What is Transom Height? The first order of business is to measure your boat for the ideal fit. })(); 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. Outboard Motor Shaft Length & HP to Boat Calculating boats.com, 1221 Brickell Avenue, 23rd Floor, Miami, FL 33131, USA. (We wont go into name-calling here, but the actual term for the cavitation plate is an anti-ventilation plate.) the propshaft below or above the pad. The boat transom can be flat with zero degree angles. Save my name, email, and website in this browser for the next time I comment. So how to measure outboard shaft length? How Low Should a Motor Set on a Pontoon Boat? (Explained) (3) Move horizontally across the chart until you hit the graph curve. (function (d) { In step 3, add another 10 cm (4") to the previous calculation in order to develop the ideal shaft length. There are a series of four to six holes at the top of the bracket, and the lower bolts actually fit into slots. If it measures anywhere from 17" to around 22", then your going to want to go with a long shaft motor. Other uncategorized cookies are those that are being analyzed and have not been classified into a category as yet. Pretty easy to figure out but like I said its crucial to pairing a motor with a boat. The standard shaft length for most outboard engines less than 125 horsepower is 20 inches. Necessary cookies are absolutely essential for the website to function properly. If your outboard motor height. Long shafts are 20-inches long. var addyd53b59933f6c3f2e8b59f1b4a6d41fa5 = 'info' + '@'; They operate as a planing surface, allowing your boat to climb to the top more quickly. This allows the engine to idle without the flow of the exhaust being restricted. Outboards designed for saltwater applications usually have longer shafts. Say the 20 shaft is a long shaft length for gas engines, but it is a short shaft length for electric outboard motors. He is also a certified marine technician and the author of a popular text on writing local history. maxMicroAmount: 0.0, At least if its too long you can raise the motor or "build up" your transom. Thats it. 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. The point where these measurements intersect is your centerline. 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. It is where the outboard is mounted, and some boat owners place the name of the boat. These are vertically aligned so the boater can make adjustments. Finding the right size is a matter of looking at what youve got and taking out the measuring tape. xmlHttp.setRequestHeader('Content-Type', 'application/json'); This would not be a good thing. debugMode: false, var h = d.getElementsByTagName("head"), 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. Since the length of the shaft of your outboard is associated with the size boat, smaller engines will generally have shorter shafts. (In the case of the faster A reverse transom that sits too high can impact the propellers of the motor and motor bracket. However, your boat will have slightly more drag which will reduce your maximum speed. boats.com is part of the Boats Group Network. enableMoreInfoLink: true, (616) 364-0666, On all contiguous US part orders over $100. Analytical cookies are used to understand how visitors interact with the website. Proper Mounting Height for an Outboard - Gone Outdoors 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. 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. You All things considered, sticking with the industry standard is best for the beginner. to where the brackets were actually resting on the transom. How high exactly do you have to raise the transom?-. s.setAttribute("rel", "stylesheet"); However, there may be times when a boater strays away from these recommendations. On the downside, a higher mount can interfere with the boaters steering capabilities. You also might not be able to lift the outboard out of the water entirely for storage. mpeInit(); 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. How do you measure a transom on an outboard motor? Ten years ago I bought my first boat. A2: Instead of changing to the short outboard shaft, you can try the Jack Plate first. Whether you already own a boat or looking for your first watercraft we are here to service your needs. This could also effect your travelling capabilities on the boat trailer. Happy boating! It was a 23-foot Crestliner Grand Cayman pontoon boat. Required fields are marked *. Basically, there are three main ways to measure motor height (that I'm aware of); probably the most common is: # 1: Height of the motor off the transom This is simply a measurement taken from the top of the transom (top of the aluminum plate on top of the transom), to the bottom of the motor "brackets". Place the clubs bottom on the ground as though it were going to be used to strike a golf ball. and I'll explain it better, (or point you to someone that can help. The average transom angle is around 14 degrees. The height of the boat transom dictates the size of the outboard motor. 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. #1: Height This was the height of my 225 Yamaha on my TR21 It also decreases the boats lift and increases the time it takes for the boat to reach plane. If the propeller fails to ventilate, the motor is mounted to low. bracket. 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? MarinePartsMan.com also says that V6 bass-boat engines have a 20-inch shaft. window.dataLayer = window.dataLayer || []; Small portable outboards ranging from 2 to 20 horsepower are usually sold only in short or long shaft versions. The cookie is used to store the user consent for the cookies in the category "Analytics". This is measured by the propeller shaft being parallel to the vessels bottom. However, you will need an understanding of how the degrees will alter the boats usability. The boater must also consider if the boat transom support is designed to bear the weight of a higher mount. If your boats transom height is 15-16, a short shaft engine is required, and if it is 20-21, a long shaft engine is required. Height Measurement: Recommended Shaft Length: 14" - 17.25" 15" Shaft (Short) 17.25" - 19.5" Varies by application 19.5" - 22.5" <>/ExtGState<>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 595.2 841.8] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> Learn More About Your Boats Systems By Joining The Born Again Boating Academy! https:/. Now that you have a better understanding of boat transom heights its time to take out the ruler and get the perfect measurements. How do you measure a transom on an outboard motor? To do so, you will want to measure at the exact center of the transom from the very top to the very bottom. This will keep the prop in the water when the boat pitches in waves, or hobby-horses. All rights reserved. These cookies ensure basic functionalities and security features of the website, anonymously. Also, how do you determine the length of an outboard transom? 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. A1: Broadly speaking, the outboard motor shaft length for pontoon boat, bass boat, or other larger boats should be long shaft. To do so, measure from the stern (back) of the boat to the midpoint of the hull on both sides. As mentioned above, the operation of the propeller relies on the transom height. You may wonder how deep your prop should be in the water. 7. How high exactly do you have to raise the transom?- - Outboard Jets 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. Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. } Its where the outboard motor is attached, and its also where some boat owners put the boats name. Check out the full chart of the Mercury outboard model code and its features. By clicking Accept, you consent to the use of ALL the cookies. If it measures 15" or with in a inch of that you will need a short shaft outboard. addyd53b59933f6c3f2e8b59f1b4a6d41fa5 = addyd53b59933f6c3f2e8b59f1b4a6d41fa5 + 'vanssports' + '.' + 'com'; As with anything, there are exceptions to the rule. help with shaft length for a kicker - iboats Boating Forums You must be still in the blue about that matter. If the height of the boat transom is off it can cause major issues. To break it down a bit more for you: Short shafts are 15-inches long. Like Westshore Marine & Leisure on Facebook! For most boaters this is a no brainer, but for the novice or inexperienced boater it may be a tougher question. storeDisplayName: "Marine Parts Warehouse", However, the motor should not be raised more than 5 inches above the standard position. This is a measurement that has been used for BassCats, I'm 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.