Long shaft outboard motors are ideal for sailboats that tend to have high transoms.
It’s also your go-to solution if you need to venture into rough open water where swamping is a distinct possibility and want a higher level of safety and efficiency at the same time.
However, how long is a long shaft outboard engine? How high should a transom be for a long shaft motor?
In this post, I will explain everything you need to know about long shaft outboard motors in detail.
Still indecisive about whether to go with a long shaft outboard motor or short shaft?
You’ve got to the right place. You will also find tips to help you make the decision easier.
Some of you might have already got a long shaft outboard motor and found it too long.
No worries. You can still make it right with some smart tools and accessories.
Table of content:
- Long Shaft Outboard Motor vs Short Shaft
- Best Long Shaft Outboard Motors
- Using Long Shaft Outboard Motor on Shorter Transom
Short Shaft vs. Long Shaft Outboard Motor
Before confirming your order or purchase, you will be asked whether you want a short or long shaft.
So what’s the difference between short and long shaft outboard motors?
Apparently, shaft length is the major difference between short and long shaft outboard motors, and it’s measured from the top of the clamp bracket to the bottom of the cavitation plate (for combustion outboards) or central of the propeller (for electric outboards), as the figure shows below.
This leads us to some further questions: How long is a short/long shaft outboard motor?
Generally speaking, 15” is a short shaft and 20” is a long shaft for combustion outboards. The measurement is a bit different for electric outboards with 25” being a short shaft and 30” being a long shaft.
Some manufacturers also offer extra short shafts (such as the 20” extra short shaft from ePropulsion Spirit 1.0 Plus) and extra/ultra-long shaft options for some special models to fit your various boating applications.
The table below gives you a quick reference on how many inches a long shaft outboard motor is for electric and combustion outboards, taking ePropulsion and Yamaha as examples.
| Comparison | Electric Outboards | Combustion Outboards |
| Extra Short Shaft Length | 20.7” (52.5 cm) | x |
| Short Shaft Length | 24.6” (62.5 cm) | 15” (38 cm) |
| Long Shaft Length | 29.5” (75 cm) | 20” (51 cm) |
| Extra Long Shaft Length | x | 25” (64 cm) |
| Ultra Long Shaft Length | x | 30” (76 cm) |
With this knowledge, you may wonder: Do I need a short or long outboard motor? How high should a transom be for a long shaft motor?
In fact, whether to get a short or long shaft outboard motor essentially depends on the length of your transom. Having a longer or shorter shaft length than needed will both cause potential problems:
- Too long of a shaft will make it hard to navigate in shallow water, cause extra drag, and even make the bow rise that creates an upward thrust that loses efficiency;
- Too short of a shaft might get the motor out of the water, especially in choppy waters, which produces the risk of overheating problems (due to the lack of water) and losing power thru water cavitation at the prop.
Therefore, be sure to measure your outboard shaft length correctly to get the ideal outboard motor for your boat.
Further Reading: How to Find Your Shaft Length
Best Long Shaft Outboard Motors
Settled your mind on a long shaft outboard motor? Check out our top 3 long shaft outboard motor recommendations for sailboats, Jon boats, and small fishing boats to make your next trip more enjoyable and fruitful.
#1. 3 HP Spirit 1.0 Plus
This best-selling 3 HP electric outboard motor offers various shaft length options (20.7” extra short, 24.6” short, and 29.5” long shaft) to fit sailboats, dinghies, fishing boats, tenders, etc.
The long shaft outboard motor is portable with a 1276Wh integrated battery. It’s super easy to pack and install with no worries about heavy batteries and extra wiring or setup.
In terms of performance, you can go 22 miles at 4.5 mph or go fishing all day long at trolling speed (with one charge, tested on a 12-foot aluminum boat with one person onboard). If you slow down the speed, the range will be greatly extended and can reach 80 miles at 2.2 mph.
Some other intelligent features with this long shaft outboard motor include a digital display that keeps you informed of the battery level all the time, a magnetic kill switch that keeps you safe onboard, and max power output adjustment that keeps your kids safe with a smaller full-throttle power.
If you are considering buying a small long shaft outboard motor for your sailboat or Jon boat, don’t miss it out. You will be impressed by the quietness and premium experience it provides, just like thousands of existing Spirit owners worldwide.
“I bought a ePropulsion spirit as an outboard to propel our yacht on windlass days. 1000 watt charged by solar will give us about 2.5 knots of speed on windless days and a flat sea. Loving it!”
#2. Navy Series Outboard Motor
The Navy Series electric outboard motor includes the 6 HP and 9.9 HP model for your selection, both coming with a long shaft at 24.6” (62.5 cm) and a shorter shaft at 29.5” (75 cm).
The long shaft electric outboard motor provides efficient and clean power for your best experience on the boat. It’s ideal for aluminum fishing boats, dinghies, daysailers, and cruising sailboats, and can be used in both freshwater and saltwater.
Thanks to direct-drive technology, the Navy Series long shaft outboard boat motor is quiet, low maintenance, and reliable in all kinds of water conditions.
Compared with the Spirit 1.0 Plus, you can go 45 miles with Navy 6.0 Evo at the speed of 5 mph (with one charge using one ePropulsion E175 battery, tested on a 12-foot aluminum boat with one person onboard). That’s three trips from the New York Aquarium to the Statue of Liberty.
If you are looking for a long shaft outboard motor for your sailboat, you will love Navy more because it features an innovative hydrogeneration function that allows you to collect electricity from wind and water.
That way, you can have more fun on the water with less worry about the battery and runtime. See what customers say about this long shaft outboard motor and its hydrogeneration capability in real-world use:
“Just spent 3 days in my small sailboat with a new Evo onboard. It was a great trip. I didn’t count on the dynamic generation because I didn’t know how much I would get from it. There were 2 times in the trip where I noted the battery percentage going up because of the dynamic generation.”
Using Long Shaft Outboard Motor on Short Transom
Sometimes you may find a good bargain on an outboard motor that has a longer shaft than needed.
Can I use a long shaft outboard motor on a short shaft boat?
The simple answer is YES and it can be easily done with a riser – a big benefit for the long shaft outboard motor.
The riser can be self-made with some decent wood or aluminum square tubing.
There are a lot of YouTube tutorials on how to make different styles of transom elevators. Click to see how Dylan uses the long shaft outboard motor on his Jon boat with a homemade riser.
Or you can simply purchase a Jack plate to raise the transom to your desired height.
Follow this video to see how to install the Jack plate outboard riser and successfully use the long Shaft outboard motor on a short transom Jon boat.
However, can a short shaft be converted to a long shaft?
You will very possibly be out of luck with a short outboard motor on a longer transom. Even with the conversion kit available, the process is very complicated and technically demanding.
Some might choose to cut down their transom to accommodate a short shaft motor. Otherwise, you will need to trade your short shaft motor for a longer one, which can take a lot of time and effort.
It’s always easier to find a transom extender for outboards than otherwise. That’s why you will hear suggestions to always go for longer instead of shorter if you are torn between a short or long shaft outboard motor.
Editor’s Note: Although a longer shaft outboard motor can be used on a shorter transom with the Jack plate, you will experience more efficiency with a motor that matches your boat without making modifications to make one work with the other.
If you need any more help finding the right long shaft outboard motor for your boat, leave a comment below and I will reply to you asap.
