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. Raising the motor increases the speed of the boat while decreasing the effort needed to turn the boat. Check out the full chart of the Mercury outboard model code and its features. 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. Gear case sits just below or at the hull depth due to the deep v. Happy boating! A transom saver, which can change the spacing between the lower unit and the trailer, negates some of the support. You also might not be able to lift the outboard out of the water entirely for storage. The outboard shaft length is the vertical distance between the top of the mounting clamp bracket and the bottom of the cavitation plate (aka the ventilation plate). Bass boats, ski boats, or center cockpit vessels will want to double-check their measurements to get it just right. maxMicroAmount: 0.0, up to the bottom of the motor brackets, (as in #1). Smaller inflatables and dinghies needshort shaft motors, whilst bigger boats require long or, in some circumstances, extreme long shaft versions. Shaft lengths are available in increments of 5. 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. Follow Westshore Marine & Leisure on Twitter! Using your existing control box and gauges will save you quite a bit of money in the end. (We wont go into name-calling here, but the actual term for the cavitation plate is an anti-ventilation plate.) var interval = setInterval(function () {
How do you measure a transom on an outboard motor? 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. You dont have to be a mathematician to determine the correct boat transom angle. 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. Smaller 12-14 foot boats can require either a short or long shaft outboard depending on the style of the boat and the brand. The distance between the ends of a transom is measured in inches. For example, you can have the Mercury outboard shaft length by model code. Repowering your boat is one of the most expensive upgrades you can make. 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. A deep Vee hull will result in a different measurement than a flatter . The greater the number, the more the drive may sway (also called tuck under or negative trim). Save my name, email, and website in this browser for the next time I comment. A: Any boat that has a 21 to 27 inch aft transom will need an extra long shaft outboard. Its where the outboard motor is attached, and its also where some boat owners put the boats name. }, 100); They keep water out of your prop and increase water pressure in the system. This is somewhat similar to #2, in that you are again measuring with a
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. If it measures between 17 and 22, you'll want to go with a long shaft motor. If the height of the boat transom is off it can cause major issues. center of the propshaft. C Cheaptoon Cadet Joined Aug 4, 2010 Messages 28 Aug 24, 2010 #4 Re: Motor height on pontoon? Actual shaft length is 21.5" on those. out the confusion. Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. 7. Take your time and understand your boat and your entire transom. hulls, such as Allisons, Bullets, Strokers, etc., this measurement could
Keep these numbers in mind if you ever have a need for a new outboard motor for your boat. AztH
^zv_ cT,E1K/rAB54| Whether you already own a boat or looking for your first watercraft we are here to service your needs. 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. var xmlHttp = new XMLHttpRequest(); Charles Plueddeman is Boats.com's outboard, trailer, and PWC expert. So how to measure outboard shaft length? The faster your boat, the more critical it is to get the sizing just right. publicId: "32bf3437d1346295e03ebcf545f9c839", Buying a boat can be an exciting purchase. 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. <>
In lower mounting, the engine is set lower than the recommended standard. 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. You reply, "Im not sure, I think its a long". %PDF-1.7
As with anything, there are exceptions to the rule. Rest the yard stick or another suitable straight edge along the keel on the bottom of the boat so that it makes a straight line aft to the outboard. document.getElementById('cloakd53b59933f6c3f2e8b59f1b4a6d41fa5').innerHTML = ''; Measure straight down to the lowest point on the hull. The lowest point will likely be directly under your drain plug if youve got one. This alone can outweigh the negatives when deciding to adjust the mount upwards. The propellers will also have trouble reaching the water. These cookies will be stored in your browser only with your consent. Extra-long shafts are 25-inches long. At least if its too long you can raise the motor or "build up" your transom. It can also improve the experience of driving a faster boat. This could also affect your travelling capabilities on the boat trailer. Among them will be first-timers or those who have recently purchased their boats. The height is approximately six inches higher than with a propeller. If you went too long it would still work but it may lack in performance. It also cuts into speed and fuel efficiency. To achieve this, the motor itself has to be attached at the correct height. It is where the outboard is mounted, and some boat owners place the name of the boat. Anything bigger than that your obviously going to need an extra long shaft. The average transom angle is around 14 degrees. This is a measurement that has been used for BassCats, I'm
Trimming in, trimming down, and trimming out are all terms that a beginning boater should learn. However, there may be times when a boater strays away from these recommendations. The pressure behind your hand dropped as you slid your hand back and forth through the water. The vertical distance between the interior of the clamp and the cavitation plate is the shaft length specified by the outboard manufacturer. brackets. Knowing how this can affect the overall operation of the boat is a factor to be considered. How can you figure out what your transom angle is?
Engine height with stepped hull at transom - before I screw things up I also love helping others, which is why I created this website. It also includes attaching the right engine. Boaters who consider going with a higher mount can see increased speeds. var h = d.getElementsByTagName("head"), measuring; you may have to "extend" the flat part of the
This would not be a good thing. However, the shaft length for smaller boats could be long or short depending on its style, speed requirement, etc. Height Measurement: Recommended Shaft Length: 14" - 17.25" 15" Shaft (Short) 17.25" - 19.5" Varies by application 19.5" - 22.5" However, there may be times when a boater strays away from these recommendations. Then adjust the motor in a higher hole with a flat head screwdriver. Beginning boaters should be aware of the boats measurements. debugMode: false, Displacement hulled vessels like sailboats and workboats can benefit from a little more space between the hull and cavitation plate, but not much. disregard the "hooks" at the front of the
It also cuts into speed and fuel efficiency. Boat Transom Heights The Beginners Guide, Buying a boat can be an exciting purchase. However, your boat will have slightly more drag which will reduce your maximum speed. Generally, the anti-ventilation plate on most engines is aligned with the bottom of the vessel. bassboat can be a bit confusing at times; hopefully this will help sort
You may wonder how deep your prop should be in the water. function mpeInit() { 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). 2 0 obj
In the case of a dinghy or johnboat, this point may be the top of the transom. The outboard comes with mounting holes and brackets. The mounting height of an outboard motor can impact the speed and handling characteristics of the boat.
The Best Way to Measure Prop to Pad | How to measure Outboard Motor Height When mounting the engine, you want the cavitation plate to be 1 above the boat bottom for every 12 away from the transom. Engine Oil Mixing Ratio Fuel 50: Engine Oil 1. Thats it. What types of boat need an extra long shaft? If it measures 15" or with in a inch of that you will need a short shaft outboard. ensure that your measurement is accurate. No one wants to have issues with a new transom or boat repairs. If you have a small boat with a 15 to 17 inch aft transom, youll most likely need a short shaft outboard. What is the Virtual Sundance Film Festival? Well, raising the outboard motor can be an easy task for you. Before we get started lets see what a boat transom is and what it does. When fighting waves from the stern, a 20-inch transom is considerably safer. Attention: Remember to measure the outboard shaft length straight up and down instead of measuring along the transom. What Kind of Fuel Does Your Marine Engine Need? The transom angle is the vertical incline of the transom and is measured in degrees. Step 2 requires the propeller's radius (check the user manual and then the technical drawing). The transom is the rear wall of the boat where the outboard engine is mounted in the middle. Step 4. You need JavaScript enabled to view it.
Long Shaft vs. Short Shaft Outboard (What Are the Differences?) This email address is being protected from spambots. Some outboards have a serial number that tells you which shaft length to go for. Mounting the outboard motor in accordance with the industry standards is important. boats.com is part of the Boats Group Network. Re: Dinghy with a long shaft motor? Copyright 1999-2023 Boats Group. Then, you can pick the right engine. h[0].appendChild(s); A yardstick will help you determine if your outboard engine is at the right height.
With this in mind, how can I determine if my outboard has a short or long shaft? a Detwiler manual jackplate. The collapsing bubbles are loaded with extremely low-pressure water vapor, which causes damage to a variety of surfaces as they collapse. #3. The boat transom can be flat with zero degree angles. To do so, take a measurement from the very top to the very bottom of the transom in the precise center. Finding the right size is a matter of looking at what youve got and taking out the measuring tape. Look at the part of your motor that would be
If youd like to see this in video format, skip to 0:44 in the below YouTube Video: Is it OK to put a long shaft outboard on a boat thats rated for a short shaft? It is unsafe to have the engine block too close to the water on a low transom. Another important measurement is the transom angle. It is very versatile as it generally . relation to pad
Selecting the Correct Size Outboard Shaft, What is the Best Outboard Motor for Saltwater, Diagnosing Common Outboard Motor Problems, Best Beginner Boats Everything You Need to Know. 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. If the height of the boat transom is off it can cause major issues.
One of the main concerns is causing the engine to overheat if not enough water reaches the engine to keep it cool. So if you are measuring the outboard shaft length for smaller boats, inflatables, dinghies, sailboat or other low-speed work boats, the cavitation plate is often about 2 below the bottom.
How to Measure a Boat Transom - Gone Outdoors He is also a certified marine technician and the author of a popular text on writing local history. 4 0 obj
Since the length of the shaft of your outboard is associated with the size boat, smaller engines will generally have shorter shafts. (Putting a
This, however, is not recommended for the beginning boater. Always weigh the risks of making adjustments. function loadScript(script) { Ten years ago I bought my first boat. Boat hulls are designed in three basic types that range from slow displacement and semi-displacement hulls to the fastest planing hulls. Because of the increased friction, cavitation reduces efficiency. 12 Small Fishing Boat Accessories to Buy Today. Buying a boat can be an exciting purchase. Most of the standard engined boats it takes shafts that are 15-30inches long. Required fields are marked *. It was a 23-foot Crestliner Grand Cayman pontoon boat. Tilt your motor until the bullet of the gearcase is
Amazon has plate extensions to allow adjustments without buying a new motor: T-H Marine Jack Plate Extension. I show you how to consistently measure your prop to pad height. :$I>M W$h"%U_yzIb?]NHg_G|r@nX eTf."SQ I would also recommend finding your maximum horsepower rating which is located on the yellow coast guard tag towards the back of your boat. Check the literature about your model boat online, and you may be surprised to find that the number is published for you. Some fishing boats can handle the motor being underwater.
How to Raise Outboard Motor on Transom? - Raising the Outboard Motor Thats a fairly simple list of symptoms, but if your motor is too low, youll probably notice at least one of them. Like Westshore Marine & Leisure on Facebook! 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. A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. This is measured by the propeller shaft being parallel to the vessels bottom. So in hopes that this will help out some new boaters this spring, here's a little rundown on outboard shaft sizes and how to figure out which one you actually need. mpeSelector: ".pt-mpe", Check out some hot FAQs to help you get the proper outboard shaft lengths. your motor will be higher.) 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. There What matters is the actual measurement in the specifications, not the name. Other factors to consider when determining the mounting height of an outboard are related to performance. This exhaust port should be about 1 inch above the water line when the boat is idling. The center is the point where your outboard motor is (ideally) located. Pretty easy to figure out but like I said its crucial to pairing a motor with a boat. How the outboard will sit on the back of the boat depends on how the transom is designed. Most of the time, adding a hydrofoil to an outboard improves performance. var path = 'hr' + 'ef' + '='; Set the end of the tape on the outside edge of the taffrail at the center and measure inward to the inside edge of the taffrail. The boat transom can be flat with zero degree angles. This is also known as the shaft length. The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. How do you measure a transom on an outboard motor? In addition, motor totes will not harm the finish of the lower unit. With it comes a lot of responsibility and new things to learn includingboat maintenanceand boat basics. If you have an outboard motor, the distance from one end to another will be found on the side or on a label near its bottom. An inch or two probably wont make a big difference, but any more than that will lead to trouble. The cookie is used to store the user consent for the cookies in the category "Analytics". Whether you already own a boat or looking for your first watercraft we are here to service your needs. Step 3: Add another 10 cm (4'') to the previous calculation for the final ideal shaft length. <>/ExtGState<>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 595.2 841.8] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>>
Beefier jack plates can be fitted should a boater be looking to mount an outboard with a shorter shaft than their transom demands. Or measure from the main engine prop up to the water line?
Setting Height of Outboard Motor - YouTube In the past, though, it housed the officers and captain of 17th, 18th and 19th century sailing ships. To make the yard stick long enough to measure the length of all the clubs, tape the ruler to the top.
Boats with more engine power and weight require longer shaft outboards for better balance. Simply start with the engine in idle, followed by, If you decide to make some custom adjustments we have the. An outboard motor can drive just about any sort of boat with proper mounting. Again, make sure that you are measuring to the flat part of the brackets;
With more than a decade of experience cruising the lakes in my Crestliner Grand Cayman pontoon boat and my Boston Whaler, I now want to share everything I've learned with my community here at Boating Hub.
Guide to Boat Transom Heights - Marine Parts Warehouse The engine must be linked to the transom at the proper height for a propeller to best meet specific boating demands. 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. Outboards designed for saltwater applications usually have longer shafts. Allowing the propeller to pull water from underneath and push it out behind the boat. 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. Small portable outboards ranging from 2 to 20 horsepower are usually sold only in short or long shaft versions. This is the dimension you'll need to know when deciding between a short shaft, long shaft or extra long shaft for your outboard motor. Place the point of a yardstick at the middle of the top of the boat transom. When you measure the width of the stern, mark the center with a grease pencil. 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 finally test your outboard, if the mount is perfect. However, the motor should not be raised more than 5 inches above the standard position. Analytical cookies are used to understand how visitors interact with the website. Now that you have a better understanding of boat transom heights its time to take out the ruler and get the perfect measurements.
Transom Outboard Engine Position - YouTube Having the cavitation plate a bit lower than the transom is preferable to having it too high. The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional". Having the cavitation plate too low will cause excess drag and reduced performance at high speeds. since 1986. priceSelector: ".price--withoutTax, span.price.price--withTax", Then open up the clamp bucket. So you should just measure the height of the boat's transom from the center down to the lowest point of the hull, and compare transom height with the outboard shaft length numbers. 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. It can also improve the experience of driving a faster boat. Safely but briskly accelerate. e-mail
Pad to bottom of
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. Each one has a totally different effect on the boats performance. Outboard Motor Shaft Length: How do I measure? 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. The boater must also consider if the boat transomsupport is designed to bear the weight of a higher mount. Take your time and understand your boat and your entire transom. Small motors built for sailboats might come in a unique configuration with an extremely long shaft since these are mounted higher off the water. Chances are the boat was designed with a specific size of outboard in mind. The transom is the flat vertical section at the rear of the boat. 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. loadScript(ptScript); Make sure that you are measuring straight up, at a 90 degree angle to
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. In lower mounting, the engine is set lower than the recommended standard. To do so, you will want to measure at the exact center of the transom from the very top to the very bottom. There are also specialty motor shaft lengths. 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. The motor is what powers the boat so the two go hand-in-hand. Before we start measuring the outboard shaft length, lets get it clear about whats referring to when we talk about the outboard shaft length.