This could also effect your travelling capabilities on the boat trailer. 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. This could also affect your travelling capabilities on the boat trailer. 1855 Alpine Avenue NWGrand Rapids, MI 49504This email address is being protected from spambots. #1: Height The mounting height of an outboard motor can impact the speed and handling characteristics of the boat. If you have a question or need additional information. These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc. 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. Plus, a low transom cut is an invitation for the water to flood the boat. It is possible that the motor could hang low while transporting on the boat trailer causing future boat repairs. Add the two measurements and you get 6 1/2". Each one has a totally different effect on the boats performance. (127 mm). What the relationship to the pontoons is, I couldn't say. d.addEventListener("DOMContentLoaded", function (e) { See diagram below. Tilt your motor until the bullet of the gearcase is Place the clubs bottom on the ground as though it were going to be used to strike a golf ball. resting on the transom if you had the motor all the way down on the boat motor brackets your motor will be higher.) (function (d) { Buying a boat can be an exciting purchase. What Types of Documents Can be Sent to your Kindle Library? var interval = setInterval(function () { The height of the boat transom dictates the size of the outboard motor. Place the bracket on the transom to the left of the main outboard or rudder. Boat hulls are designed in three basic types that range from slow displacement and semi-displacement hulls to the fastest planing hulls. The boat transom can be flat with zero degree angles. Analytical cookies are used to understand how visitors interact with the website. The average transom angle is around 14 degrees. One of the factors in determining the height of the outboard is the placement of the exhaust port on the lower unit of the outboard engine. In the photo above, we've measured from the motor bracket to the top of You'll need a short shaft outboard if it's 15 or less than an inch shorter. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. 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). 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). Small motors built for sailboats might come in a unique configuration with an extremely long shaft since these are mounted higher off the water. Actual shaft length is 21.5" on those. The standard shaft length for most outboard engines less than 125 horsepower is 20 inches. 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! This alone can outweigh the negatives when deciding to adjust the mount upwards. This email address is being protected from spambots. Here we will guide you in how to get the right boat transom height. 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. Check out the full chart of the Mercury outboard model code and its features. AztH ^zv_ cT,E1K/rAB54| Many single-engine boats mount a smaller auxiliary motor for emergency use. It does not store any personal data. Boaters who consider going with a higher mount can see increased speeds. There are also specialty motor shaft lengths. mpeSelector: ".pt-mpe", 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. Before we start measuring the outboard shaft length, lets get it clear about whats referring to when we talk about the outboard shaft length. Ten years ago I bought my first boat. Finding the right size is a matter of looking at what youve got and taking out the measuring tape. So its easier and safer to communicate with the dealer with the exact measurement of outboard shaft length in order to get the right model. The same is true for the newest, high-powered offshore fishing boats, where triple or quadruple motor setups are becoming more and more common. 5/rC,aQhsK@Q. Triton. If you are running a twin-engine setup, then measure the same distance from each clamping plate to the bottom of the hull. It also includes attaching the right engine. 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. The cavitation plate is the horizontal surface of the lower unit immediately above the propeller. 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. Hold the tape on the top, center of the taffrail and measure straight down to the point, usually a sharp angle, where the transom joins the bottom of the boat. Safely but briskly accelerate. To do so, take a measurement from the very top to the very bottom of the transom in the precise center. Whether you already own a boat or looking for your first watercraft we are here to service your needs. It also cuts into speed and fuel efficiency. (Putting a What matters is the actual measurement in the specifications, not the name. However, the motor should not be raised more than 5 inches above the standard position. You reply, "Im not sure, I think its a long". You can find your Mercury outboard model code on an ID plate or sticker. As summer approaches there will be more boaters taking to the water. These are vertically aligned so the boater can make adjustments. If it measures anywhere from 17" to around 22", then your going to want to go with a long shaft motor. Whats the best height for my boat motor? If the propeller fails to ventilate, the motor is mounted to low. Outboard Motor Shaft Length: How do I measure? out the confusion. So how to determine the outboard shaft length? s.setAttribute("href", "https://cdn.paytomorrow.com/css/pt-mpe.min.css"); Mounting the outboard motor in accordance with the industry standards is important. 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. Higher mounting decisions should be left to the professionals. Safely but briskly accelerate. e-mail The distance between the ends of a transom is measured in inches. maxTerm: 36, If you go too short your more than likely going to cavitate and loose power. When the boattransom is too low, the motor could end up underwater. 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. Before we get started lets see what a boat transom is and what it does. As you can see, the measurement is about 2 1/2". If so, send me an 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. For most boaters this is a no brainer, but for the novice or inexperienced boater it may be a tougher question. As a result, the issue is whether my boat need a short shaft or long shaft motor. Boat transom angles play a pivotal role in the flexibility of the boats trimming abilities. If the height of the boat transom is off it can cause major issues. If you have already measured you transom tip to bottom to be 20", then if you place aux sdieways to central engine your available transom height will be probably 1"-1.5" " higher and work perfecty. With it comes a lot of responsibility and new things to learn includingboat maintenanceand boat basics. All rights reserved. Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. What types of boat need an extra long shaft? The motor is what powers the boat so the two go hand-in-hand. Engine Oil Type Genuine or Recommended 2str Engine Oil. Beyond motorboats designed for large outboards, you will see outboards hanging on the sterns of everything from small canoes to large cruising sailboats. I live for the weekends when I can go out on the water and escape the stress of life on land. 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. A reversetransom that sits too high can impact the propellers of the motor and motor bracket. Any owner seeking the last bit of speed from an outboard-powered boat should grab a yard stick. On most newer center consoles and offshoreboat transoms might include a rear door leading to a swim platform as well as a molded setback bracket. The first order of business is to measure your boat for the ideal fit. 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. Here we look at the effects of standard, lower and higher mounting. These cookies track visitors across websites and collect information to provide customized ads. Two years ago, I bought a Boston Whaler to fish off the coast. jackplate to a point level with the top of the transom. 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. The amount of degrees the transom leans back from vertical is known as the transom angle. In addition, motor totes will not harm the finish of the lower unit. I hope this helps someone out in their search for a new or newer outboard this season. Another important measurement is the transom angle. It is where the outboard is mounted, and some boat owners place the name of the boat. When mounting the engine, you want the cavitation plate to be 1 above the boat bottom for every 12 away from the transom. Some may call it a standard length while others may call it a short or a long shaft. 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. An inch or two probably wont make a big difference, but any more than that will lead to trouble. On the downside, a higher mount can interfere with the boaters steering capabilities. As a yacht designer and boater, I prefer longer shafts. This is somewhat similar to #2, in that you are again measuring with a Trimming in, trimming down, and trimming out are all terms that a beginning boater should learn. 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. a Detwiler manual jackplate. Anything bigger than that your obviously going to need an extra long shaft. 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.