Measure from the top of the transom to the bottom of the hull. Save my name, email, and website in this browser for the next time I comment. Raising an outboard higher on the transom can reduce drag and raise top speed. If you have a fast boat, getting the outboards cavitation plate at the same level of the hull will ensure quick hole shot and fast top-end speeds. The standard shaft length for most outboard engines less than 125 horsepower is 20 inches. #2. Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. 1 0 obj There are instances where a lower mount may be okay. The first step is to determine the height of your boat's transom. The cookie is used to store the user consent for the cookies in the category "Other. Owners of bass boats, RIBs, or offshore fishing boats need to get this right. High powered boats usually only come in long and extra-long variants. 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. By clicking Accept, you consent to the use of ALL the cookies. addyd53b59933f6c3f2e8b59f1b4a6d41fa5 = addyd53b59933f6c3f2e8b59f1b4a6d41fa5 + 'vanssports' + '.' + 'com'; When trimming your motor, they provide you a greater bow response. Some may call it a standard length while others may call it a short or a long shaft. 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. If measuring an existing outboard: Measure from the inside top of mounting bracket down to anti-cavitation plate above propeller (this is the largest plate/fin directly above the propeller). If so, send me an They operate as a planing surface, allowing your boat to climb to the top more quickly. 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. This restriction includes most fishing boats and longer sailboats. (Putting a Smaller 12-14 foot boats can require either a short or long shaft outboard depending on the style of the boat and the brand. A reverse transom that sits too high can impact the propellers of the motor and motor bracket. August 9/08). will be to the flat part; if you measure to the bottom of the brackets Use the mounting bracket on the motor to know where it will sit on the boat. Many single-engine boats mount a smaller auxiliary motor for emergency use. 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. The correct shaft length for your boat depends on a few factors. 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. When the jet drive is on the motor, set the height so that the leading edge of the intake is flush with the boat bottom. Propshaft in This cookie is set by GDPR Cookie Consent plugin. This would not be a good thing. It is extremely important that the boater understands the significance of the transoms height. An outboard motor can drive just about any sort of boat with proper mounting. 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). Pretty easy to figure out but like I said its crucial to pairing a motor with a boat. The propellers will also have trouble reaching the water. 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. The transom is the flat vertical section at the rear of the boat. Attention: Remember to measure the outboard shaft length straight up and down instead of measuring along the transom. Your email address will not be published. The transom angle is the vertical incline of the transom and is measured in degrees. The distance between the ends of a transom is measured in inches. minAmount: 300.0, What Kind of Fuel Does Your Marine Engine Need? 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. When mounting the engine, you want the cavitation plate to be 1 above the boat bottom for every 12 away from the transom. Other boats that need long shafts are. Some boats are equipped with transom-hung outboards while others have a bracket. Measure the area of the transom directly where the engine will be mounted. straight edge on the top of the transom to "extend" it out 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. Then finally test your outboard, if the mount is perfect. You reply, "Im not sure, I think its a long". It also cuts into speed and fuel efficiency. Then adjust the motor in a higher hole with a flat head screwdriver. Beginning boaters should be aware of the boats measurements. Gear Oil Quantity 195ml(6.6 Fl.oz.) var h = d.getElementsByTagName("head"), 5/rC,aQhsK@Q. The transom in a boat today is a place to hang your outboard motor. However, the shaft length for smaller boats could be long or short depending on its style, speed requirement, etc. d.addEventListener("DOMContentLoaded", function (e) { This distance is very important to the performance of you boat. Outboards designed for saltwater applications usually have longer shafts. The same is true for the newest, high-powered offshore fishing boats, where triple or quadruple motor setups are becoming more and more common. Variables to consider when determining the mounting height include the size and style of the boat and the length of the outboard motor's shaft. 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. 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. Check out the Westshore Marine & Leisure Youtube page! When the boat transom is too low, the motor could end up underwater. Smaller boats may use adjustable jack plates that can be changed to fit any outboard. Later in the article is an image that shows you exactly where to measure. For really big boats, the biggest and baddest six- or eight-cylinder outboards can have extra-extra long shafts up to 30 inches. Upstream Securitys Disruptive Telematics Technology, The challenges of scaling a cloud-based security system, OneStreams unified platform streamlines financial data management, OneStreams impact on the financial software market. Mounting the motor lower on the boat transom can create excessive spray, increase case drag, reduce underwater clearance, and negatively impact faster boats. Bass boats, ski boats, or center cockpit vessels will want to double-check their measurements to get it just right. How to Buy a Boat: Tips for a First Time Buyer, Top 10 New Fishing Boats for Under $20,000, What Type is Right for You? The pressure behind your hand dropped as you slid your hand back and forth through the water. 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. Your goal is to measure how the outboard will sit, so start from the clamping plate and follow the centerline of the hull. A reversetransom that sits too high can impact the propellers of the motor and motor bracket. 2019s List of the Best Recreational Pontoon Boats for Sale. Beginning boaters should be aware of the boats measurements. Before we get started lets see what a boat transom is and what it does. Follow Westshore Marine & Leisure on Wordpress! Other uncategorized cookies are those that are being analyzed and have not been classified into a category as yet. 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). s = d.createElement("script"); As summer approaches there will be more boaters taking to the water. To achieve 35 mph with a 6 hp engine, the total weight is 135 lbs (boat motor fuel passengers). want to measure from the transom to the flat part of this bracket, 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. Well, raising the outboard motor can be an easy task for you. The shaft length for outboard motors has nothing to do with the water line. Here we look at the effects of standard, lower and higher mounting. 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. If your boat is newer and the manufacturer is still in business, you might also want to try to give them a call. 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. (We wont go into name-calling here, but the actual term for the cavitation plate is an anti-ventilation plate.) The Effects of Standard, Lower and Higher Mounting. displayPrimeOffers: true, Generally, the anti-ventilation plate on most engines is aligned with the bottom of the vessel. The boat transom can be flat with zero degree angles. <> "brackets". endobj Now that you have a better understanding of boat transom heights its time to take out the ruler and get the perfect measurements. It is possible that the motor could hang low while transporting on the boat trailer causing future boat repairs. One of the great things about an outboard motor is how versatile it is. When fighting waves from the stern, a 20-inch transom is considerably safer. Raising the motor increases the speed of the boat while decreasing the effort needed to turn the boat. However, you will need an understanding of how the degrees will alter the boats usability. If it measures between 17 and 22, you'll want to go with a long shaft motor. It doesnt matter if you have a fiberglass boat, bay boat, big or small boat. 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. up to the bottom of the motor brackets, (as in #1). How Transom Height Is Measured 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. 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. } As mentioned above, the operation of the propeller relies on the transom height. Check out some hot FAQs to help you get the proper outboard shaft lengths. Check the literature about your model boat online, and you may be surprised to find that the number is published for you. Re: Dinghy with a long shaft motor? It can also improve the experience of driving a faster boat. and I'll explain it better, (or point you to someone that can help. The collapsing bubbles are loaded with extremely low-pressure water vapor, which causes damage to a variety of surfaces as they collapse. This alone can outweigh the negatives when deciding to adjust the mount upwards. This could also affect your travelling capabilities on the boat trailer. Simply start with the engine in idle, followed bytrimming the motor out by one-half to full trim.