While this is the case there is certain saltwater motors that are extra extra long at 30. Cavitation is when the propeller is out of the water due to the boat forming a wake of "air bubbles" or "vapor cavities" around the prop. 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. 7. Before we start measuring the outboard shaft length, lets get it clear about whats referring to when we talk about the outboard shaft length. Basically, there are three main ways to measure motor Raising the motor increases the speed of the boat while decreasing the effort needed to turn the boat. Your at your local outboard dealer shopping for a new motor and the salesman hits you with the question, "short or long shaft?". For example, you can have the Mercury outboard shaft length by model code. If you decide to make adjustments, please consult a marine engine dealer about the boat design. This email address is being protected from spambots. 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. Commonly, the transom angle ranges from 0-30 degrees, with the average transom angle set at 14 degrees. 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. What the relationship to the pontoons is, I couldn't say. Make sure that you are measuring straight up, at a 90 degree angle to The prop will be in cleaner, harder water as it advances farther aft, making it more efficient. So how to determine the outboard shaft length? Doing this can have adverse effects. There is a simple test to see if your outboard motor is set at the best height. You also have the option to opt-out of these cookies. 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. Attention: Remember to measure the outboard shaft length straight up and down instead of measuring along the transom. Beginning boaters should be aware of the boats measurements. 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. What's the best height for my boat motor? It is possible that the motor could hang low while transporting on the boat trailer causing future boat repairs. Mounting the motor lower on the boat transom can create excessive spray, increase case drag, reduce underwater clearance, and negatively impact faster boats. Whether you already own a boat or looking for your first watercraft we are here to service your needs. This alone can outweigh the negatives when deciding to adjust the mount upwards. You The height is approximately six inches higher than with a propeller. (function () { It also includes attaching the right engine. out the confusion. Step 4. The lowest point will likely be directly under your drain plug if youve got one. Owners of bass boats, RIBs, or offshore fishing boats need to get this right. })(); (Putting a Figuring out how to measure motor height on a Your email address will not be published. Buying a boat can be an exciting purchase. Safely but briskly accelerate. This alone can outweigh the negatives when deciding to adjust the mount upwards. Other boats that need long shafts are. Other factors to consider when determining the mounting height of an outboard are related to performance. Trimming in, trimming down, and trimming out are all terms that a beginning boater should learn. Measure straight down to the lowest point on the hull. d.addEventListener("DOMContentLoaded", function (e) { If your boat is newer and the manufacturer is still in business, you might also want to try to give them a call. With it comes a lot of responsibility and new things to learn including boat maintenance and boat basics. 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. Outboard Motor Shaft Length: How do I measure? 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. Since the ventilation plate & foil are burried under water it is obviously too low. Measure from the top of the transom to the bottom of the hull. 3 0 obj It also cuts into speed and fuel efficiency. The anti-cavitation plate above the prop needs to be within an inch of the bottom of the transom, therefore, the prop should be well below the transom. bracket. motor brackets 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. Most transom savers can support up to a 150HP motor, which is sufficient for most regular boats. MarinePartsMan.com also says that V6 bass-boat engines have a 20-inch shaft. It is where the outboard is mounted, and some boat owners place the name of the boat. To achieve 35 mph with a 6 hp engine, the total weight is 135 lbs (boat motor fuel passengers). Whether you already own a boat or looking for your first watercraft we are here to service your needs. Step 2: Three Variables to Consider 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). This placement is not only recommended but it will give you the best performance compared to something that is too long or too short. Most of the time, adding a hydrofoil to an outboard improves performance. A reversetransom that sits too high can impact the propellers of the motor and motor bracket. Its still smart to measure it yourself though, just in case, the design changed over the years. s.setAttribute("type", "text/javascript"); Safely but briskly accelerate. They operate as a planing surface, allowing your boat to climb to the top more quickly. s.setAttribute("src", script); #3. Save my name, email, and website in this browser for the next time I comment. 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. I also love helping others, which is why I created this website. This allows the engine to idle without the flow of the exhaust being restricted. Increased RPM and additional horsepower feed the need for speed. 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. Plus, a low transom cut is an invitation for the water to flood the boat. Cavitation plates are used on the bottom components of boats to help them operate better. August 9/08). ensure that your measurement is accurate. Higher mounting decisions should be left to the professionals. If the height of the boat transom is off it can cause major issues. The performance of these boats depends on quite a lot of factors, but getting the outboard length just right is an essential first step. Necessary cookies are absolutely essential for the website to function properly. Setting Height of Outboard Motor - YouTube 0:00 / 0:46 Setting Height of Outboard Motor nates90 71 subscribers Subscribe 83 Share 63K views 7 years ago #boatservice #outboardmotor. With the long side (22 1/2), place a carpenters square ) in opposition to the keel. These cookies will be stored in your browser only with your consent. Yes, if there is adequate space while the engine is tilted in the up position, a larger shaft length than what is specified may be used. 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. Boaters who consider going with a higher mount can see increased speeds. However, you will need an understanding of how the degrees will alter the boats usability. A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. Industry standards dictate that for short shaft engines the transom height should be 15. The Effects of Standard, Lower and Higher Mounting. Outboards designed for saltwater applications usually have longer shafts. It also cuts into speed and fuel efficiency. The transom angle is the vertical incline of the transom and is measured in degrees. Boats with more engine power and weight require longer shaft outboards for better balance. For vessels with transom-mounted outboards, you can easily figure out which type of outboard you need to get. the aluminum plate on top of the transom), to the bottom of the motor The cookie is used to store the user consent for the cookies in the category "Analytics". Be sure to measure carefully and research thoroughly before diving in. Gear Oil Quantity 195ml(6.6 Fl.oz.) Place the rulers end on the ground behind the club and let the club to rest on top of it. 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. 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. https://www.bornagainboating.com/Get Your Born Again Boating Clothing! PayTomorrow.mpeInit({ endobj Ill also explain the difference between short and long shafts and how they vary by type of boat. With some boats I have a pretty good idea as to what length motor should be hung on them. Check out the Westshore Marine & Leisure Youtube page! You need JavaScript enabled to view it. addyd53b59933f6c3f2e8b59f1b4a6d41fa5 = addyd53b59933f6c3f2e8b59f1b4a6d41fa5 + 'vanssports' + '.' + 'com'; primeApr: 12.99, It can also improve the experience of driving a faster boat. (We wont go into name-calling here, but the actual term for the cavitation plate is an anti-ventilation plate.) Youll need a short shaft outboard if its 15 or less than an inch shorter. See diagram below. With it comes a lot of responsibility and new things to learn including, Why your boat transom needs to be the right height, The pros and cons of properly mounting the outboard motor to the transom, Standard mounting is always best for the beginner, Of course, its always best to go with standard practices when choosing the, Lower mounting is not for the beginning boater, Mounting the motor lower on the boat transom, There is a simple test to see if your outboard motor is set at the best height. These are vertically aligned so the boater can make adjustments. Happy boating! And the rule of thumb is that you should keep the cavitation plate level with the bottom or keel of the boat. Sluggish speeds, poor handling, heavy spray, porpoising, or even water pushing up into the cowling are all signs that an outboard is set too low. The pros and cons of properly . They keep water out of your prop and increase water pressure in the system. When fighting waves from the stern, a 20-inch transom is considerably safer. Outboard motors can be fitted to a variety of boats, so manufacturers have standardized their engines to go on virtually anything. brackets. (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. 4 0 obj Theyre also useful if the back of your boat has a non-standard measurement. mpeInit(); It was a 23-foot Crestliner Grand Cayman pontoon boat. The motor is what powers the boat so the two go hand-in-hand. Amazon has plate extensions to allow adjustments without buying a new motor: T-H Marine Jack Plate Extension. Recommended Engine Oil 2-Stroke Outboard Motor Oil. He is also a certified marine technician and the author of a popular text on writing local history. Some fishing boats can handle the motor being underwater. Boats that use longer outboard shafts include: It is possible that the motor could hang low while transporting on the boat trailer causing future boat repairs. Measure the area of the transom directly where the engine will be mounted. It can also improve the experience of driving a faster boat. The propellers will also have trouble reaching the water. This is probably the worst case scenario out of the two. Or measure from the main engine prop up to the water line? Cutting the transom down is the only legal method to utilize a short shaft engine on a tall transom. As mentioned above, the operation of the propeller relies on the transom height. On the downside, a higher mount can interfere with the boaters steering capabilities. Of course, its always best to go with standard practices when choosing thebest boat engine. You may wonder how deep your prop should be in the water. Allowing the propeller to pull water from underneath and push it out behind the boat. The pressure behind your hand dropped as you slid your hand back and forth through the water. The brackets can add 1 inch to the overall mounting height of the outboard. This exhaust port should be about 1 inch above the water line when the boat is idling. 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.

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