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. The height is approximately six inches higher than with a propeller. <>/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 Factors indicates the adjustment affected by on your boat type, the outboard working environment, and the transom distance as discussed above. (Putting a The propellers will also have trouble reaching the water. The transom is the flat vertical section at the rear of the boat. 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. It is extremely important that the boater understands the significance of the transoms height. 5/rC,aQhsK@Q. Other boats that need extra long shafts are: Read my other articles on outboard motors. 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. } Knowing how this can affect the overall operation of the boat is a factor to be considered. Once you know what will fit on your hull, you can fine-tune your choice based on the performance youre looking for and how you use the boat. Other uncategorized cookies are those that are being analyzed and have not been classified into a category as yet. Use the mounting bracket on the motor to know where it will sit on the boat. Another important measurement is the transom angle. 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. My family and I used it to fish, ski (yes, you can ski behind a pontoon boat), and cruise the lakes near our home. It is where the outboard is mounted, and some boat owners place the name of the boat. Boaters who consider going with a higher mount can see increased speeds. a Detwiler manual jackplate. minAmount: 300.0, When the right length motor is hung on the transom of a boat, the cavitation plate (the large plate that extends out over the propeller) should be even with the very bottom of the boat. On this type of boat, if you are in doubt, default to the longer-shafted outboard. The boater must also consider if the boat transomsupport is designed to bear the weight of a higher mount. Analytical cookies are used to understand how visitors interact with the website. This, however, is not recommended for the beginning boater. The motor is what powers the boat so the two go hand-in-hand. 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. To do so, measure from the stern (back) of the boat to the midpoint of the hull on both sides. since 1986. With such an important, long-term, and expensive upgrade, its never a bad idea to double-check. Commonly, the transom angle ranges from 0-30 degrees, with the average transom angle set at 14 degrees. One of the main concerns is causing the engine to overheat if not enough water reaches the engine to keep it cool. 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. 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. Cavitation plates are used on the bottom components of boats to help them operate better. If it measures 15" or with in a inch of that you will need a short shaft outboard. Actually there is no designated letter for short shaft. Outboard shaft length plays a crucial role in the performance of your boat. As mentioned above, the operation of the propeller relies on the transom height. These cookies will be stored in your browser only with your consent. want to measure from the transom to the flat part of this bracket, Two years ago, I bought a Boston Whaler to fish off the coast. Add the two measurements and you get 6 1/2". former editor at Boating Magazine and contributor to many national publications Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. 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. and I'll explain it better, (or point you to someone that can help. #3. You will also risk hitting bottom or submerge objects more frequently such as rocks or logs. The height of the boat transom dictates the size of the outboard motor. If you go too short your more than likely going to cavitate and loose power. 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. Recommended Engine Oil 2-Stroke Outboard Motor Oil. The mounting height of the outboard engine is the equivalent of the distance between the base of the motor and the top of the propeller. If it measures 15" or with in a inch of that you will need a short shaft outboard. 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. Doing so, will put the propeller right below the boat. Since the ventilation plate & foil are burried under water it is obviously too low. clearInterval(interval); To break it down a bit more for you: Short shafts are 15-inches long. s.setAttribute("type", "text/javascript"); Take your time and understand your boat and your entire transom. How do you measure a transom on an outboard motor? ), Al Shields 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. would be more accurate.) The vertical distance between the interior of the clamp and the cavitation plate is the shaft length specified by the outboard manufacturer. Will Charpentier is a writer who specializes in boating and maritime subjects. All boats are different, and the motor manufacturers produce a variety of standard lengths. logoColor: "original", The transom angle is the vertical incline of the transom and is measured in degrees. This would not be a good thing. 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. What matters is the actual measurement in the specifications, not the name. Step 3: Add another 10 cm (4'') to the previous calculation for the final ideal shaft length. Each one has a totally different effect on the boats performance. jackplate to a point level with the top of the transom. var prefix = 'ma' + 'il' + 'to'; By clicking Accept, you consent to the use of ALL the cookies. 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. Then test the boat and adjust the height, if necessary . This is handy if youre shopping for second-hand outboards or looking to sell the one that came with your boat. Or it can have an angle degree as high as 30. What's the best height for my boat motor? Owners of bass boats, RIBs, or offshore fishing boats need to get this right. For most boaters this is a no brainer, but for the novice or inexperienced boater it may be a tougher question. This will keep the prop in the water when the boat pitches in waves, or hobby-horses. With it comes a lot of responsibility and new things to learn includingboat maintenanceand boat basics. However, there may be times when a boater strays away from these recommendations. Wherever the outboard clamping bracket is, use this as the basis for measurement. Follow Westshore Marine & Leisure on Wordpress! Some may call it a standard length while others may call it a short or a long shaft. xmlHttp.send('{"store_id":"369079","timezone_offset":"-5","timestamp":"2023-03-04T05:39:31.71020200Z","visit_id":"e2642be3-34e5-4a48-b89d-639d139834e0","channel_id":1}'); This allows the engine to idle without the flow of the exhaust being restricted. var interval = setInterval(function () { It also includes attaching the right engine. 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. As summer approaches there will be more boaters taking to the water. If you have a small boat with a 15 to 17 inch aft transom, youll most likely need a short shaft outboard. In lower mounting, the engine is set lower than the recommended standard. The flat part of the bracket that rests on the transom when mounted will give you the same point of reference as the transom does on the boat. parallel with the straight edge. The boater must also consider if the boat transom support is designed to bear the weight of a higher mount. Beginning boaters should be aware of the boats measurements. Of course, its always best to go with standard practices when choosing thebest boat engine. This is also known as the shaft length. All rights reserved. Mounting the motor lower on the boat transom can create excessive spray, increase case drag, reduce underwater clearance, and negatively impact faster boats. 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. For really big boats, the biggest and baddest six- or eight-cylinder outboards can have extra-extra long shafts up to 30 inches. It doesnt matter if you have a fiberglass boat, bay boat, big or small boat. You need JavaScript enabled to view it. Be sure to measure carefully and research thoroughly before diving in. The standard installation of an outboard has the top of the transom of the boat at the same level as the bottom of the motor portion of the outboard. If the height of the boat transom is off it can cause major issues. 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. Then, you can pick the right engine. relation to pad If the propeller fails to ventilate, the motor is mounted to low. With some boats I have a pretty good idea as to what length motor should be hung on them. Its where the outboard motor is attached, and its also where some boat owners put the boats name. Required fields are marked *. A long shaft engine requires a height of 20 and extra-long shaft engines will need a transom height of 25. maxAmount: 6500.0, Now that you have a better understanding of boat transom heights its time to take out the ruler and get the perfect measurements. If you are running a slower boat, the exact location of the ventilation plate is less important. Measure the area of the transom directly where the engine will be mounted. ), and place it on the bottom of the pad in the center. It also cuts into speed and fuel efficiency. 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. Boat transom angles play a pivotal role in the flexibility of the boats trimming abilities. A transom saver, which can change the spacing between the lower unit and the trailer, negates some of the support. Triton. The height of the boat transom dictates the size of the outboard motor. brackets. Boat hulls are designed in three basic types that range from slow displacement and semi-displacement hulls to the fastest planing hulls. It is possible that the motor could hang low while transporting on the boat trailer causing future boat repairs. These allow the mounting of a standard length outboard behind the transom. Attention: Remember to measure the outboard shaft length straight up and down instead of measuring along the transom. A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. AztH ^zv_ cT,E1K/rAB54| With the long side (22 1/2), place a carpenters square ) in opposition to the keel. | Sitemap, The Marine Parts Warehouse Outboard Museum, OBR Powerhead / Shortblock Warranty Claim Form, Remanufactured vs. No one wants to have issues with a new transom or boat repairs. There are a series of four to six holes at the top of the bracket, and the lower bolts actually fit into slots. While this is the case there is certain saltwater motors that are extra extra long at 30. 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. trimming the motor out by one-half to full trim. addyd53b59933f6c3f2e8b59f1b4a6d41fa5 = addyd53b59933f6c3f2e8b59f1b4a6d41fa5 + 'vanssports' + '.' + 'com'; Then open up the clamp bucket. This is somewhat similar to #2, in that you are again measuring with a Measure from the top of the transom to the bottom of the hull. Well, raising the outboard motor can be an easy task for you. I hope this helps someone out in their search for a new or newer outboard this season. Charles Plueddeman is Boats.com's outboard, trailer, and PWC expert. This is the dimension you'll need when selecting a width for your outboard motor's mounting bracket. The outboard comes with mounting holes and brackets. The standard shaft length for most outboard engines less than 125 horsepower is 20 inches. How can you figure out what your transom angle is? It varies between different motors and boats. Measuring the shaft length can be done in various ways, but the most common way is by using a tape measure. The transom is the back of the boat where the motor is hung. Measure from the top of the transom to the bottom of the hull. Safely but briskly accelerate. The performance of these boats depends on quite a lot of factors, but getting the outboard length just right is an essential first step. xmlHttp.setRequestHeader('Content-Type', 'application/json'); resting on the transom if you had the motor all the way down on the boat This, however, is not recommended for the beginning boater. Take the center measurement from the top to the bottom of the hull. Simply start with the engine in idle, followed by trimming the motor out by one-half to full trim. 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. your motor will be higher.) Next, measure from your centerline to where the outboard will be mounted on each side. As a dealer I don't really like hearing this because there is a chance it could go either way and you have to get it right. Check the literature about your model boat online, and you may be surprised to find that the number is published for you. Simply start with the engine in idle, followed by, If you decide to make some custom adjustments we have the. He is a bracket. Make sure that you are measuring straight up, at a 90 degree angle to For over five years he has worked as a newspaper reporter and historic researcher. The clamp bracket on the latest Mercury Four-Stoke-model outboards has five mounting bolt holes spaced .75 inches apart. A: The short answer is Yes. s = d.createElement("script"); Keep these numbers in mind if you ever have a need for a new outboard motor for your boat.