Ten years ago I bought my first boat. Take your time and understand your boat and your entire transom. <> It moves an outboard up and down to optimize performance and enable a boat to venture into shallower water than it might otherwise. 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. would be more accurate.) Kicker Motor Shaft Length - This Old Boat - Lake Ontario United - Lake How Low Should a Motor Set on a Pontoon Boat? (Explained) This alone can outweigh the negatives when deciding to adjust the mount upwards. 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 motor length corresponds to the transom height of the boat, measured from the keel to gunwale at the transom. Safely but briskly accelerate. Basically, there are three main ways to measure motor bracket forward with a straight edge to where you can then measure up Some outboards have a serial number that tells you which shaft length to go for. %PDF-1.7 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. 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. His works have appeared in regional newspapers in North Dakota and in "North Dakota Horizons" and "Cowboys and Indians" magazines. :$I>M W$h"%U_yzIb?]NHg_G|r@nX eTf."SQ If you have a question or need additional information. want to measure from the transom to the flat part of this bracket, What Types of Documents Can be Sent to your Kindle Library? 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. The center is the point where your outboard motor is (ideally) located. 2 0 obj The propellers will also have trouble reaching the water. Generally, the anti-ventilation plate on most engines is aligned with the bottom of the vessel. (function () { 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. All rights reserved. Top 10 Choices for Boaters, Mercury Introduces 600HP V12 Verado Outboard Engine, The Outboard Expert: Tohatsu Propane Outboard Engine. If you have a small boat with a 15 to 17 inch aft transom, youll most likely need a short shaft outboard. d.addEventListener("DOMContentLoaded", function (e) { As summer approaches there will be more boaters taking to the water. Any questions? 5/rC,aQhsK@Q. Its still smart to measure it yourself though, just in case, the design changed over the years. Boaters who consider going with a higher mount can see increased speeds. I would also recommend finding your maximum horsepower rating which is located on the yellow coast guard tag towards the back of your boat. Theyre also useful if the back of your boat has a non-standard measurement. All you need to do is measure how much to rise. As a yacht designer and boater, I prefer longer shafts. The height of the boat transom dictates the size of the outboard motor. He is a However, you will need an understanding of how the degrees will alter the boats usability. (function (d) { (In the case of the faster Adjusting the mounting height of an outboard on the boat transom can affect performance and every boat can be different, so actual on-water testing is best. And thats usually the case since the electric outboards are designed with larger and more efficient propeller that needs longer shaft. Take a long straight edge, (long carpenter's level or long |. The vertical distance between the interior of the clamp and the cavitation plate is the shaft length specified by the outboard manufacturer. How to Find Your Shaft Length | ePropulsion However, there may be times when a boater strays away from these recommendations. Problems with getting the ventilation plate too low include slower hole-shot and lower top-end speeds. Many boat transoms are modified to use a different length of outboard by using a bracket. Then finally test your outboard, if the mount is perfect. I show you how to consistently measure your prop to pad height. This could also affect your travelling capabilities on the boat trailer. Installing a Kicker Motor Bracket - Gone Outdoors These cookies will be stored in your browser only with your consent. #2. 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. Trimming in, trimming down, and trimming out are all terms that a beginning boater should learn. Using your existing control box and gauges will save you quite a bit of money in the end. To break it down a bit more for you: Short shafts are 15-inches long. Engine Oil Type Genuine or Recommended 2str Engine Oil. The cookie is used to store the user consent for the cookies in the category "Other. For really big boats, the biggest and baddest six- or eight-cylinder outboards can have extra-extra long shafts up to 30 inches. So you should just measure the height of the boats transom from the center down to the lowest point of the hull, and compare transom height with the outboard shaft length numbers. The height of the boat transom dictates the size of the outboard motor. Chances are the boat was designed with a specific size of outboard in mind. Oftentimes you will want to adjust the outboard shaft length in order to improve the boat performance such as speed. 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. To measure the transom height, measure from the center on for transom (rear of the boat). It can also improve the experience of driving a faster boat. Then open up the clamp bucket. Most of the standard engined boats it takes shafts that are 15-30inches long. Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. Copyright 1999-2023 Boats Group. Which Navigation Lights Does Your Boat Need? A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. Your email address will not be published. He is also a certified marine technician and the author of a popular text on writing local history. Height Measurement: Recommended Shaft Length: 14" - 17.25" 15" Shaft (Short) 17.25" - 19.5" Varies by application 19.5" - 22.5" Or measure from the main engine prop up to the water line? <>/ExtGState<>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 595.2 841.8] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> The pressure behind your hand dropped as you slid your hand back and forth through the water. s = d.createElement("script"); It does not store any personal data. Place the point of a yardstick at the middle of the top of the boat transom. The transom angle is the vertical incline of the transom and is measured in degrees. I live for the weekends when I can go out on the water and escape the stress of life on land. Measure straight down to the lowest point on the hull. Typical motor lengths include the following. The pros and cons of properly . For slower boats, its less critical to. The transom angle is the vertical incline of the transom and is measured in degrees. There is a simple test to see if your outboard motor is set at the best height. 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. Beyond motorboats designed for large outboards, you will see outboards hanging on the sterns of everything from small canoes to large cruising sailboats. Boost Speed with Outboard Engine Height Adjustments A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. A yardstick will help you determine if your outboard engine is at the right height. For example, you can have the Mercury outboard shaft length by model code. If it measures anywhere from 17" to around 22", then your going to want to go with a long shaft motor. Later in the article is an image that shows you exactly where to measure. There The engine may be lifted one inch for every eight to ten inches of distance between the transom and the prop, according to a boat riggers rule of thumb. It also cuts into speed and fuel efficiency. since 1986. 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). 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. MPW eBay Store - Thousands of New OEM Old Stock Parts! Read the measurement on the transoms bottom. This was the height of my 225 Yamaha on my TR21 The motor is what powers the boat so the two go hand-in-hand. The point where these measurements intersect is your centerline. This would not be a good thing. Step 2 requires the propeller's radius (check the user manual and then the technical drawing). You will also risk hitting bottom or submerge objects more frequently such as rocks or logs. Bass boats, ski boats, or center cockpit vessels will want to double-check their measurements to get it just right. Boaters who consider going with a higher mount can see increased speeds. Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. It is extremely important that the boater understands the significance of the transoms height. For boats equipped with a bracket, calculate the same measurement but based on the bracket and not the transom.