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Short Shaft Outboard Vs Long Shaft

If you constantly struggle with accuracy off the tee, a shorter driver shaft can be a better option for your game. Hitting more fairways is the quickest way to a more enjoyable round of golf, and a shorter length driver shaft is a quick and easy fix that helps many beginners hit the sweet spot more often. The best driver to have in the bag is the one you can consistently hit on the center of the clubface, not the one you can hit the farthest.The length of today’s average driver shaft measures between 45 and 45.75 inches. Callaway’s new Rogue ST drivers come equipped with 45.5 inch shafts, and Taylormade’s Stealth drivers measure even longer, at 45.75 inches.

How do I know if I need a long shaft or short shaft?
Running. It up here stretching. It down we could see that it stops at exactly 20 inches so we knew that for this boat. We would need to use our long shaft model. If we took this measurement.
To understand why the stock shafts in drivers have lengthened so much over time, it is important to understand how golf clubs are marketed and sold. While other golf clubs are marketed based on different traits – spin, launch, feel, etc. – drivers and woods are almost exclusively advertised and sold based on their distance.

Our team of experts at Tell Me More Golf encourage you to speak with your local PGA professional, club fitter, or pro shop employee to see if a shorter driver shaft would benefit your swing. is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to large golf equipment retailers provide access to an in store launch monitor and will let you compare different drivers they have available free of charge.

What is the most common outboard shaft length?
Standard shaft lengths are 15, 20 and 25″ (38, 50 and 63 cm). Those shaft lengths are an industry standard but there are exceptions. For mid-range engines, the most common shaft length is 20″ (508 mm).
A club with high forgiveness will not deviate as far from the original target line, while a club with low forgiveness will end up much further from the intended target. For this reason, more forgiveness = more accuracy.The longer driver usually ends up on an “out to in” club path, leading to the dreaded distance killing slice. A squarely hit ball by a shorter driver with the correct club path will fly further than a poorly struck ball with a longer one.

Does shaft length matter on outboard motor?
If you are looking for an ePropulsion electric outboard for your boat, choosing the correct shaft length is important. If you go too long it would still work but it may lack performance. You will also risk hitting bottom or submerged objects more frequently such as rocks.
While golf club manufacturers today offer longer than ever stock driver shafts in their latest models, the vast majority of golfers will be more accurate and play better with a shorter driver shaft.While the shaft length is usually provided by the manufacturer, or easily obtainable by simply measuring the disconnected shaft from end to end, there is a specific process required to determine playing length.

The team of experts at Tell Me More Golf recommend comparing a shorter shafted driver and a standard length one head to head on a launch monitor, and see the results for yourself.
There are two different ways to measure driver shaft, by shaft length and by playing length. The shaft length only refers to the shaft itself, while the playing length takes the whole club into account, and is the measurement used by the USGA to determine if a club conforms to maximum size specifications.

The same concept applies to a longer shafted driver. While a longer shaft produces more power, it can also make a club harder to control and more prone to mishits.
Many manufacturers also produce drivers in a “draw biased” model, where the clubface is angled slightly shut instead of square to the target. There are a few different clubhead and shaft configurations available that produce different ball flights, and some unbiased launch monitor testing can help set a player up with the perfect equipment.A shorter driver shaft makes the club more manageable, comfortable, and easier to control. Unless you are a taller golfer, it is unlikely that the standard shaft length is optimal for your swing. PGA Tour players are the best golfers in the world, and they have even learned to put their egos aside and use whichever driver length lets them hit the most fairways possible. As a recreational golfer, you should definitely not be more concerned with chasing distance than the professionals, and a shorter shaft will likely lead to an increase in distance if you struggle with a slice.

While distance and accuracy are not mutually exclusive, many golfers sacrifice accuracy when chasing more distance off the tee. This is mostly due to the tendency to swing harder and faster, causing less consistent swings and more mishits.
The most common mistake beginner golfers make when shopping for a new driver is choosing the driver that produces the highest launch monitor yardage, even if they only reach that number on one perfect swing. Club manufacturers understand this tendency, and know that extra long shafts will produce that one booming drive with peak distance, regardless of consistency.

Can you change a short shaft outboard to a long shaft?
Your short shaft motor can also be sold as a long shaft with a Bay Kit. A long shaft motor can be sold as an extra long with a Bay Kit. Motors can be easily converted back to fit any customers need. Bay Kits come complete with all parts needed to make the conversion.
Rickie Fowler famously shortened his driver down to 43.5 inches back in 2017, finding it gave him better control and made it easier to hit fairways. He would use the extra boost to go on and win the Honda Classic, leading many recreational golfers to speculate about the length of their own drivers.If you walk into any golf supply retailer today, you’ll see many different brands of drivers in various models and variations. What they will all have in common is the significant length of the stock shafts that come standard. First, lay your driver down on a flat surface. A beach towel or carpeted surface is best to avoid scratches or other damage. Next, find the point where the club head comes into contact with the flat surface at a 60 degree angle. This area is referred to as the “heel” of the club head. Once you have located this area, known as the “heel” of the club, measure from there to the butt of the club – and you have your playing length.

What is the advantage of a short shaft?
A shorter shaft can not only increase fairway percentage, it can also help straighten out the ball flight of slicers compared to the standard length off the shelf. It is easier for the vast majority of golfers to keep a shorter club in “the slot” and on the correct club plane compared to a longer one.
Some golfers have trouble getting the ball up in the air, while others hit their driver far too high. Both of these can be addressed with the correct clubhead and loft combination.

What shaft length should I use outboard?
Measure from the top of your transom to the bottom of your keel. If it is from 15″ to 17″ long you’ll need to get a Tohatsu outboard with a “short” shaft. If it is from 20″ to 22″ long you’ll need our “long” shaft outboard.
Many golfers will notice much better accuracy and control with the shorter driver, as well as a much tighter shot dispersion. Even if the longer driver produces a slightly higher yardage, it’s only worth it if it has the accuracy to match. It is much better to hit the ball 250 yards in the fairway compared to 275 deep in the woods.A shorter shaft can not only increase fairway percentage, it can also help straighten out the ball flight of slicers compared to the standard length off the shelf. It is easier for the vast majority of golfers to keep a shorter club in “the slot” and on the correct club plane compared to a longer one.

With the gradual leap in average driver length over the years, many average golfers have had a tough time maintaining accuracy, and have found the longer club to be awkward and tougher to control.It is very important to understand how these all important distance numbers are measured. To determine how far today’s driver will launch a ball, the golf club being tested is placed in the mechanical “hands” of a swing robot. A swing robot can repeat the exact same swing motion over and over, and be adjusted to different swing speeds. Golf club testers pair these high tech robotic golfers with the latest launch monitor technology to test clubs and gather data.

The saying “distance is king” thoroughly applies when it comes to the way modern drivers are designed today. A longer shaft leads to a longer swing arc, giving the clubhead more distance and time to generate speed.
Greater forgiveness in a golf club leads to greater accuracy. The term forgiveness refers to how far the ball lands from its original target line on a mishit shot.

If you are having trouble dropping the club into “the slot,” a shorter shaft can be more manageable and easier to keep on the correct club plane. A shorter shaft also makes it easier for many players to properly rotate their hands and wrists through the ball at impact, leading to a square clubface. A straight shot or a slight draw will fly and roll out much farther than a slice, leading to significantly more manageable second shots into the green.
While swing robots are helpful to test golf equipment and gather raw data, they do not represent the golf swings seen on most golf courses. In reality, the average golfer’s swing is far from repeatable, and many golfers struggle to hit the center of the clubface on a consistent basis. Most golfers also struggle to keep the longer club on the correct plane throughout the swing, leading to hooks and slices that fly farther out of bounds than ever previously possible.No two golf swings are exactly alike, and using a launch monitor when testing out new drivers is the best way to compare the hard data and see which is best suited for your game.

Long shafts offer improved performance, maneuverability, and safety features compared to short shaft outboards but may require a longer transom height and a larger fuel tank, raising costs. Short is more budget-friendly, compact, and easily transported but provides lower performance levels. Extra-long shafts cater to boats with higher transoms offering additional advantages in specific situations.Adjustable mounting brackets can help boaters find the optimal balance and stability for their boats by allowing them to fine-tune the position of the outboard. By adjusting the height and angle of the engine, you can ensure that the boat remains level and stable, providing the best possible performance and handling in various water conditions.

Underpowered boats will struggle to reach top speeds and may have difficulty handling rough water conditions. On the other hand, overpowered boats can be hard to control and may exceed the manufacturer’s recommended limits, compromising safety and stability.

Deciding between a short, long, or extra-long shaft outboard can be challenging. Carefully considering factors such as your boat’s size, intended use, environment, and transom height is essential for making the right decision. Moreover, it’s crucial to evaluate the compatibility of an outboard with your boat and determine if upgrades or extra features are necessary.A: To find the correct shaft length, measure the vertical distance from the top of the transom to the bottom of the hull, also known as the transom height. Match this measurement with the manufacturer’s specifications for each shaft length.

How to tell the difference between a long shaft and short shaft outboard?
It’s about 20 inches but the best way to know which size outboard to put on your boat measure your transom. If it’s approximately. 15 inches then it will use a short shaft outboard motor.
A: The shaft length can impact the outboard motor’s performance depending on the boat size and transom height. Choosing the correct shaft length ensures optimal boat performance, stability, and fuel efficiency.When choosing the right outboard, there are several factors to consider, such as your boat’s size, intended use, and the environment in which it will operate. Among these factors, the shaft length of the outboard motor plays a significant role.

Short shafts are typically more suitable for navigating shallow water, as they have a higher propeller position, reducing the risk of hitting underwater obstacles or the bottom.
The three main outboard shaft lengths available are short, long, and extra-long shafts. Each type has advantages and limitations, depending on your boat and specific needs. This article aims to comprehensively compare these different shaft lengths, helping you make an informed decision.Please note that ePropulsion has a different shaft length measurement from gas-powered outboards. For electric outboards, the shaft length is measured from the top of the clamp bracket to the center of the propeller. For gas outboards, it’s measured from the top of the clamp bracket to the anti-ventilation plate.

For most small dinghies and aluminum boats under 15ft or 4.5m, extra short shaft and short will work, depending on the transom height, some over 40 cm / 15.7 inches, some not.If you are looking for an ePropulsion electric outboard for your boat, choosing the correct shaft length is important. If you go too long it would still work but it may lack performance. You will also risk hitting bottom or submerged objects more frequently such as rocks. If you go too short, that’s the worst scenario as you‘re more than likely going to cavitate.To find the suitable shaft length, the principle is to make sure the top of the propeller is matched to the lowest point of the transom. Hard to put it into practice? Well, in order to get the right shaft length, first, measure the transom height, the length from the top of the boat transom to the bottom of the boat.

It’s always worth checking with your local dealer on which shaft length they recommend for your boat and local conditions. If you still have any questions regarding the shaft length, don’t hesitate to contact us. You can also download the technical drawings of ePropulsion outboards via our download centre.
For daysailers and short one-design racing sailboats, it depends on the position of the outboard mount. If you choose Spirit 1.0, we suggest you keep the outboard mount at a lower position so XS will work. That’s because XS takes less space to store inside the cabin.I’m the founder and chief editor here at Kite Ship. The electrification of boating is the most exciting thing to happen to the marine industry in a generation! Welcome, and I hope that we can provide the portal you need to dive into the world of electric propulsion and power.

If the balance is changed, the flow pattern over the propellor blades is disturbed (called cavitation), which causes an immediate loss of thrust, and over time this can cause pitting damage to the back of the blade.
Based on the example’s 28.5 inches (72.4 cm) shaft length, the only compatible long-shaft electric outboard motor would be the EPropulsion Spirit One Plus.The shaft length of an outboard motor needs to be carefully calculated. Once the boat’s dimensions have been measured and the optimal shaft length is known, the model motor can be selected.

Do I need a long or short shaft outboard?
If it measures 15″ or with in a inch of that you will need a short shaft outboard. If it measures anywhere from 17″ to around 22″, then your going to want to go with a long shaft motor. Anything bigger than that your obviously going to need an extra long shaft.
To ensure that the propellor is in free water and not shielded by the boat’s hull, and add an additional 4 inches (10cm) to the shaft length. This will help ensure it is outside the hull’s water turbulence and prevent the propellor from cavitating.These are precisely sized, and if the shaft were to be reduced, it would involve a completely new shaft assembly and replacement of the relevant components. A propellor generates a positive (high pressure) water pressure in the front of the blade and a negative (low pressure) on the back of the blade. The pressure differential is what drives the boat forward. This article discusses the difference between long and short-shaft outboard motors and the effects of the wrong shaft being installed. We also demonstrate how to measure the correct size shaft and match some brands based on their shaft length.Electric outboard motors generally have the motor mounted on the lower unit; The only connections are the electric power cables. Depending on the motor model, the new shaft may be installed and the wiring shortened to match.

If long shaft outboards are installed on a boat with a “short shaft” transom height, and dependent on the boat’s draft, there will be a danger of the prop striking the lake or river floor.The shaft length protruding below the boat’s keel may also cause additional drag. This can affect top-end speed and fuel economy (or battery endurance.) Once you have measured the transom and calculated the required shaft length, we recommend you investigate which manufacturers have the optimal electric propulsion systems for your needs. A short shaft outboard engine is a type of marine propulsion system commonly used for small boats, such as inflatable dinghies, tenders, and small fishing boats. As the name suggests, the lower unit of the outboard motor has a shorter vertical length compared to a standard or long shaft outboard.For over 30 years we’ve been supplying a leading range of marine engines and equipment, including the short shaft outboards in this category. If you have any questions about outboard engines, our highly experienced team are on hand to provide honest, unbiased advice. Call us on 01634 295 233, email [email protected] or visit us in-store!

We ship all our orders via our quick and secure, fully-tracked courier service, ensuring that your order is shipped promptly and with the high standards that we strive for from point of purchase all the way through to delivery at your door.

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As well as Mariner Outboards, we also stock a leading range of Electric Outboard Motors, including ePropulsion Outboard Motors which are lightweight, nimble and perfect for dinghies, fishing boats and sailboats. In addition, we also stock trolling motors which are extremely popular with those who own fishing boats.The short shaft outboard is designed to work best on boats with a transom height of 15 to 17 inches, which is lower than the height required for standard or long shaft outboards. One advantage of a short shaft outboard is that it is more manoeuvrable in shallow waters, which can be beneficial for anglers and boaters who frequently navigate through shallow streams or inlets. Additionally, these engines tend to be more affordable and lighter in weight than other types of Mariner outboards, which can be a significant factor for boaters who need to transport their boat and engine on a regular basis.

Let’s assume you have just purchased a new dinghy and you don’t know what size motor to pair with it. In order to choose the correct size gas outboard or trolling motor, you will need to make two different measurements on your boat. Here we will go over the two different measurements needed.
The most important information is figuring out what size shaft you need for your inflatable boat. This is a quick and easy measurement that anyone can do with a ruler. Simply measure from the top of the transom to the bottom of the hull. On most inflatable dinghies and Newport Vessels inflatable boats, this will measure to be between the range of 15-17”. This measurement dictates that your boat requires a “short” shaft gas outboard motor. If the measurement is 20-22”, you will need to consider a “long” shaft motor. It is very unlikely, but any transom to hull measurement larger than 22” will require an “ultra long” shaft for optimal performance.

Knowing how to correctly measure motor shaft length and how to measure the correct length for your inflatable boat is extremely useful information. Not only is it important for new dinghy owners, but also current owners that are looking to upgrade.To measure the shaft length on a trolling motor, you will need to measure from the bottom of the motor head to the top of the propeller housing. This length may vary by an inch or two, but round to the nearest even number to get the motor’s rated shaft length.

To measure the shaft length on an outboard, you will need to measure from the top of the mounting clamp bracket on the outboard, down to the anti-ventilation plate (commonly referred to as the cavitation plate). This measurement will vary between 15-17” for a short shaft motor, 20-22” for a long shaft motor and 25-27” for ultra long shafts. While these sizes may vary, you will want to check that the anti-ventilation plate lines up with the hull of the inflatable boat to achieve optimal performance.
You will still need to start your measurement at the top of the transom like earlier, but you only have to measure down to the waterline. This measurement will vary depending on weight, sea conditions and the type of boat. Add 10”, that is needed below the water, to this measurement to get the recommended minimum shaft length. Add 12” to the waterline measurement to get a more comfortable fit. If the length is in between sizes or equal to your measurement, move to the larger length.If you own a motor and you are looking for an inflatable boat to mount it onto, it is important to know the specifications of your motor, especially the length. Getting the wrong size motor could lead to underperformance or worse, damage to the motor.

Trolling motors are slightly different in the measurements required to make a correct purchase. Trolling motors do not need to line up with the bottom of the hull to operate at top performance. In order for a trolling motor to perform properly, the motor compartment needs to be submerged 10”-12” below the surface of the water. This measurement will come in handy later. If you own an inflatable boat or are looking to purchase one, getting an outboard motor or trolling motor for your boat has crossed your mind. Gas outboards are ideal for most dinghy owners that are looking for speed and power. Trolling motors are also a great alternative for owners looking for more green solutions with less of a price tag. If you are new to boating, it can be tough to know which one will best fit your inflatable dinghy. Getting the right shaft length is vital to the performance of the inflatable and ensuring your motor doesn’t bottom out. In this article, we will discuss the best sizing options for inflatable boats and how to measure a motor to ensure it will work for your setup. The shaft length is then chosen so that it is longer than the table, but not too long. With an engine too short, the propeller will not be enough in the water, with an engine too long, it will be too submerged (CQFD !). Indeed, for the engine to be correctly installed, the propeller must be positioned under the hull and the anti cavitation plate (the metal plate horizontally above the propeller is more or less – we will see the exact settings in another subject – at the bottom of the hull. It is a good idea to check these measurements – as well as the denominations – with the engine vendor. Indeed certain brands allow themselves small deviations – often insignificant – but which can pose problem.

If you go to an outboard engine dealer to buy a model, they will necessarily ask you for the length of the tree you need. This length depends on the height of your boat’s transom.
To measure a transom, measure the distance between the tip of the V at the center of the hull and the top of the transom at the center (not on the sides!).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.

For proper mounting height the Spirit 1.0 instruction manual Does Not add 4″ to the transom height (top of transom to bottom of boat), so the top of the propeller is 4″ below the boat bottom. Why does the manual advise the minimum length rather than the ideal length?
Hi, I would also like clarification please – your manual states the top of the propeller should sit between 100 and 150mm below the lowest point of the hull, but this page suggests 0mm below – could you clarify? For reference, my boat has a 400mm deep transomIt’s always worth checking with your local dealer on which shaft length they recommend for your boat and local conditions. If you still have any questions regarding the shaft length, don’t hesitate to leave a message to our official Facebook.

Hi Solar, you can contact our sales manager Alvin([email protected]) for further informations about the anti-cavitation plate for spirit series, thanks!
I have a Gemini 3400 sailing catamaran. We are interesting in mounting the ePropulsion Evo 6.0 on the central transom. This transom would require a mounting brack. We have 17″ if vertical space on the transom to mount a jack for the motor. The bottom of the central transom is 15″ above the water level. Do you think the long shaft would work well? Would the propeller be submerged? Do you have a mounting jack you would recommend?

To find the suitable shaft length, the principle is to make sure the top of the propeller is matched to the lowest point of the transom with at least an extra 10 cm (4’’) space to ensure good water flow underneath the boat.
Let’s take the Spirit 1.0 Evo Remote, radius of whose propeller is 5.5’’ as shown in the technical drawing, for an example. To match the 1964 16′ Starcraft aluminum boat with 21’’ transom height, the shaft length is supposed to be calculated as the following: This site uses cookies to personalize your experience and analyze site traffic. By clicking accept or continuing browsing the site, you are agreeing to our use of cookies. See our Privacy Policy here. Hi, the transom height of my boat is 38cm. According to your shaft lenght recommendation I should use an extra short shaft. But when i make the calculation transom height (38cm) + extra 10cm + prop radius (14cm), the result is 62cm. Only 0,5 cm less than the short shaft lenght of 62,5 cm. So, should I use the XS or S shaft?Considering ordering the Spirit 1.0 Plus. My transom height is 14″ which meets the 15.7″ max transom height criteria of the Xtra Short Shaft. I have heard complaints that the props is too close to the surface of the water. Looking for any feedback or recommendation as to the shaft length? We do go into the shallows from time to time, so I am trying to avoid the extra 4″ of depth with the Short shaft if possible.

Hi, I have googled the Waterbay boat and found this measurement. It shows the transom height is around 53cm, which is suitable for the Spirit Long shaft. But it’s better to have your boat measured as well, just in case.
I have a new Sea Eagle PaddleSki 437 pontoon type boat. It is in my garage, from the top of the transom to the concrete floor is approx. 20 inches, with my weight in the back it may sink lower into the water. What shaft do you recommend S Shaft or L Shaft?This article suggests lining up the top of the propeller to the lowest point of the transom. However, in every photo and video on your website that shows the propeller under water, it appears that the top of the propeller is at least 4-5 inches below the lowest point of the transom. Why?

Can I use a long shaft outboard on a dinghy?
On most inflatable dinghies and Newport Vessels inflatable boats, this will measure to be between the range of 15-17”. This measurement dictates that your boat requires a “short” shaft gas outboard motor. If the measurement is 20-22”, you will need to consider a “long” shaft motor.
Hello Jeff, the mounting height of the outboard affects the running speed seriously.When the mounting height is too high, ventilation may occur to waste power.When the mounting height is too low, the water resistance will increase and it will lead to efficiency and running speed reducing.Thanks!

Hey Jim, we have the same boat. What did you end up with? Does the PaddleSki 437 transom actually sit 20 above the water or more like 17” once it’s loaded on the water?
Hey, my transom height is 37cm, so i should take the XS shaft according to your shaft length recommendation. But when i calculate tramsom high (37cm) + extra 10cm + prop radius (14cm), the result is 61 cm. That’s very close to the S shaft lenghth of 62cm. So, which shaft should I use?

Hello, I have a 2022 Gala F360 with a 21″ Linear measurement taken tight to the transom in a straight line. The transom angles back about 10ºish. The Gala website calls for a 20″ shaft length gas motor. What would you recommend for Spirit 1.0 shaft length if I will be boating in a mix of shallow and deep water? Thanks!
Hi David, to find the suitable shaft length, the principle is to make sure the top of the propeller is matched to the lowest point of the transom. Thank you.First of all, how to identifying a 15 inch engine from a 20 inch engine; This is fairly easy with OMC (Johnson, Evinrude, and Gale) engines, as the 20 inch versions from the 50’s and 60’s, of no more than 40 hp, always had an adapter piece added to the “leg” of the engine. Shown here are photos of two 1957 Johnson 18 hp outboard motors, identical except that one is a 15 inch engine, and the other is a 20 inch engine. It is fairly easy to pick out the adapter section added just above the lower unit of the 20 inch engine.Because of confusion caused by the introduction of the 25 inch engines, which are sometimes referred to as “long” shaft engines, leaving the 20 inchers to be called “short’ shafts, I suggest we dispense with all the “short” and “long” nomenclature, and instead refer to the particular engines by the “inch” measurements, and since I only discuss “old”engines, that will limit us to 15 inch and 20 inch engines. Through most of the 50’s and 60’s, nearly all outboards (there were exceptions) where available in either version, although as the engines become larger and larger, exceeding 100 hp in the early 60’s, and exceeding 150 hp in the mid 70’s, most of the bigger engines were only available in the 20 inch “long” shaft version. If, however one intends to use a 40 hp OMC outboard dating from, say 1962 until 1982, then you will probably find used engines split about 50:50 between 15 inch and 20 inch versions. And larger engines, say 60 hp and above, 1962 and newer, will almost always be 20 inch versions, say probably about 95% or so. Now, how does one identify which engine a particular boat is set-up to use? Again the yardstick or ruler will come in handy; one merely measures the height of the transom at the motor mounting point. If that measurement is 15 to 16 inches, then the transom is for a 15 inch outboard. A measurement of 20 to 21 inches indicates that a 20 inch engine is called for. Just one complication; the “height’ of the transom is the vertical measurement from the engine mounting point down to the plane of the boat’s bottom. Since the transom will have some “rake” to it, the yard stick will only touch the top of the transom, not the bottom. the measurement is NOT made by holding the yardstick directly on the transom. Note that few transoms will measure at exactly 15 or 20 inches, and that most motors have about an extra inch or so of length. It generally will not cause any harm to have the lower unit a little deeper in the water than what would be ideal, but an engine mounted too shallow may have problems with cooling water circulation and also with propeller ventilation (air getting into the prop, causing it to lose it’s “bite” on the water and causing the engine to “rev-up” while the boat slows down). Also, as a home-boat-builder you should be aware that how you build the boat can affect how “deep” the motor needs to be mounted. For example, If the boat has a large “keel” or “skid” on its bottom, this protrusion needs to be tapered or streamlined so as not to affect the water flowing into the propeller; otherwise, the motor needs to be mounted deeper so that the propeller is below the level of the offending item. For example, if one intends to power one’s boat with a used OMC-built outboard of under 20 hp, and older than 1970, then the 15 inch transom is the correct choice, as very few of these engines will be found in 20 inch versions; I would guess that about 98% of such engines that I have seen are 15 inchers.

A perusal of local boat dealers’ used motor displays will give one an idea of just what is available in one’s particular area. A little research will provide some guidance to those who wish to build their vessel before they have secured their “prime mover.”
The sharp-minded reader (and what Duckworks reader would not be sharp-minded?) will immediately ask, “can a 15 inch engine be converted to a 20 inch version, and also the other-way-around?” The short answer is “yes,” the engines can be converted back and forth, but there are several parts and pieces necessary to make the conversion. The vertical driveshaft comes in two lengths, as do the water tubes that conduct cooling water from the water pump in the lower unit to the powerhead, and one would need the appropriate parts. Also, the vertical “shift shaft” comes in two lengths as well; however, there was a five-inch-long coupler available to allow a 15 inch engine to be converted to a 20 inch version without disassembling the lower unit to install the 20 inch shift shaft. If your engine has this extended coupler, replacing it with a standard coupler will work, but you still need the other pieces. So it is probably best to try to buy the version of the engine that you need, rather than to count on a conversion.Considerations of the boat’s design aside, it is wise to keep in mind that, unless one is buying a new outboard, one must build one’s boats to accept those outboard motors that are going to be prevalent in the market; in other words, unless you already have your outboard, do not build your boat to specs. that require an engine that will be difficult to obtain in the used motor market in your locality.

Do I need long or short shaft outboard?
If it measures 15″ or with in a inch of that you will need a short shaft outboard. If it measures anywhere from 17″ to around 22″, then your going to want to go with a long shaft motor. Anything bigger than that your obviously going to need an extra long shaft.
As to whether you should build your boat with a 15 inch or a 20 inch transom, well that depends upon the design of the boat and also how you intend to obtain your outboard motor. A design that specifies a 15 inch transom can usually be modified to a 20 inch transom with few ill effects. but one must carefully consider freeboard concerns when modifying a design specifying a 20 inch transom, to a 15 inch transom. In either case, a dialogue with the craft’s designer is probably in order for those builders who are unsure as to the implications of such a design change.These percentages are my guesses, based on looking at an awful lot of outboards, and not based on any hard research. Also, local characteristics may affect those percentages; geographic areas containing large numbers of sailboats, for example, will offer more 20 inch versions of smaller outboards than geographic areas with few sailboats.

First, a little history; through some form of evolution, it evolved in the early days of outboard motors that they would , generally, be designed to be mounted on a boat transom measuring 15 inches in height. At a later point in time, when it become apparent that increased freeboard might be desirable on larger boats, a second “standard” of a 20-inch-high transom was established. The 15 inch engines were referred to as “standard” or “short” shaft engines, while the 20 inch engines were referred to as “long” shaft engines.
In the late 80’s, with the increased popularity of deep-V offshore boats, outboards designed for 25 inch transoms began to be available, although these are almost always engines in excess of 100 hp. Only the smallest of engines, say under 40 hp, are still available in the 15 inch “short” shaft version.I often hear asked how one can tell the difference between a “long shaft” and a “short shaft” outboard. Another frequent question is how one determines if an existing boat is set-up for a long shaft or short shaft engine. And finally, should a home-built boat be built to accept a long shaft or short shaft engine?.

Repowering your boat is one of the most expensive upgrades you can make. Be sure to measure carefully and research thoroughly before diving in. Happy boating!Smaller boats may use adjustable jack plates that can be changed to fit any outboard. 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. Brackets are also handy for boats that do not have flat transoms, like canoe-stern sailboats or fan-tailed motor vessels. Later in the article is an image that shows you exactly where to measure. I’ll also explain the difference between short and long shafts and how they vary by type of boat. Ideally, you want the outboard’s cavitation plate, also called the anti-ventilation plate, to be at the same level as the bottom of your hull. This will ensure the best performance. How the outboard will sit on the back of the boat depends on how the transom is designed. Some boats are equipped with transom-hung outboards while others have a bracket.If you are running a twin-engine setup, then measure the same distance from each clamping plate to the bottom of the hull. 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.

Many boat transoms are modified to use a different length of outboard by using a bracket. Offshore vessels are often equipped with a large mounting bracket so that the transom can be left at full height. This provides seaworthiness and offers maximum protection from large seas. These allow the mounting of a standard length outboard behind the transom.
Ten years ago I bought my first boat. It was a 23-foot Crestliner Grand Cayman pontoon boat. My family and I used it to fish, ski (yes, you can ski behind a pontoon boat), and cruise the lakes near our home. Two years ago, I bought a Boston Whaler to fish off the coast. I live for the weekends when I can go out on the water and escape the stress of life on land.I also love helping others, which is why I created this website. Over time, Boating Hub has grown into a resource for boating enthusiasts around world.

If you’re going the other way around and trying to figure out how long the shaft on your outboard is, measuring it is equally easy. This is handy if you’re shopping for second-hand outboards or looking to sell the one that came with your boat.
For boats equipped with a bracket, calculate the same measurement but based on the bracket and not the transom. Wherever the outboard clamping bracket is, use this as the basis for measurement.A: The answer varies by boat, but here are some rules of thumb for matching a short shaft outboard to your boat. If you have a small boat with a 15 to 17 inch aft transom, you’ll most likely need a short shaft outboard. Other boats that need short shafts are: Picking the right shaft length for your outboard is an essential step in getting the best performance from your boat. If you have a fast boat, getting the outboard’s cavitation plate at the same level of the hull will ensure quick hole shot and fast top-end speeds. Owners of bass boats, RIBs, or offshore fishing boats need to get this right. It will ensure that the outboard’s trim will be effective, and it will save you gas too. Since the length of the shaft of your outboard is associated with the size boat, smaller engines will generally have shorter shafts. Small portable outboards ranging from 2 to 20 horsepower are usually sold only in short or long shaft versions. High powered boats usually only come in long and extra-long variants. For really big boats, the biggest and baddest six- or eight-cylinder outboards can have “extra-extra long” shafts up to 30 inches.Beefier jack plates can be fitted should a boater be looking to mount an outboard with a shorter shaft than their transom demands. They’re also useful if the back of your boat has a non-standard measurement. With a jack plate, you can mount it exactly where you want it. Use the mounting bracket on the motor to know where it will sit on the boat. 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. Measure from there down to the top of the cavitation plate, also known as the anti-ventilation plate. The cavitation plate is the horizontal surface of the lower unit immediately above the propeller. There are also specialty motor shaft lengths. Small motors built for sailboats might come in a unique configuration with an extremely long shaft since these are mounted higher off the water. The same is true for the newest, high-powered offshore fishing boats, where triple or quadruple motor setups are becoming more and more common.A: The short answer is – Yes. You can use a longer shaft than recommended and your boat will work fine. However, your boat will have slightly more drag which will reduce your maximum speed. You’ll also want to pay attention when you’re in shallow water because your prop will be lower than normalNo 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. All boats are different, and the motor manufacturers produce a variety of standard lengths. Finding the right size is a matter of looking at what you’ve got and taking out the measuring tape. But, how do you measure it?

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.Displacement hulled vessels like sailboats and workboats can benefit from a little more space between the hull and cavitation plate, but not much. Remember, if you use a longer outboard shaft than you need you will be increasing your draft. You also might not be able to lift the outboard out of the water entirely for storage.

It’s important to note that manufacturers call their models different things. Some may call it a “standard” length while others may call it a short or a long shaft. What matters is the actual measurement in the specifications, not the name. For vessels with transom-mounted outboards, you can easily figure out which type of outboard you need to get. Measure from the top of the transom to the bottom of the hull. Your goal is to measure how the outboard will sit, so start from the clamping plate and follow the centerline of the hull. Measure straight down to the lowest point on the hull. For vee-shaped hulls, the lowest spot of the hull will come to point, while on flat-bottomed boats it will be more or less level. The lowest point will likely be directly under your drain plug if you’ve got one. The faster your boat, the more critical it is to get the sizing just right. If your boat planes, pay extra attention to getting the shaft length as close to perfect as possible. An inch or two probably won’t make a big difference, but any more than that will lead to trouble. Problems with getting the ventilation plate too low include slower hole-shot and lower top-end speeds. Bass boats, ski boats, or center cockpit vessels will want to double-check their measurements to get it just right. The performance of these boats depends on quite a lot of factors, but getting the outboard length just right is an essential first step.If your boat is newer and the manufacturer is still in business, you might also want to try to give them a call. Chances are the boat was designed with a specific size of outboard in mind. If you are looking to repower, they may be able to offer some sage advice. Check the literature about your model boat online, and you may be surprised to find that the number is published for you. It’s still smart to measure it yourself though, just in case, the design changed over the years. With such an important, long-term, and expensive upgrade, it’s never a bad idea to double-check.If you are running a slower boat, the exact location of the ventilation plate is less important. Having the cavitation plate a bit lower than the transom is preferable to having it too high. This will keep the prop in the water when the boat pitches in waves, or hobby-horses. Workboats, sailboats, and displacement-hulled boats fall into this category. On this type of boat, if you are in doubt, default to the longer-shafted outboard.

The correct shaft length for your boat depends on a few factors. The first order of business is to measure your boat for the ideal fit. Once you know what will fit on your hull, you can fine-tune your choice based on the performance you’re looking for and how you use the boat.
Picking the right shaft length is mostly a factor of the transom height or the back of the boat. But in many cases, it’s a little more complicated than that alone. Boat hulls are designed in three basic types that range from slow displacement and semi-displacement hulls to the fastest planing hulls.One of the great things about an outboard motor is how versatile it is. An outboard motor can drive just about any sort of boat with proper mounting. Beyond motorboats designed for large outboards, you will see outboards hanging on the sterns of everything from small canoes to large cruising sailboats. Many single-engine boats mount a smaller auxiliary motor for emergency use.