How to Find Your Shaft Length
Updated: Feb 25
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.
The principle is to make sure the top of the propeller is lower than the lowest point of the transom, and ideally, it’s lower exactly for the length of the propeller blade. 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.
After that, you could choose the recommended shaft length based according to the transom height.
In most cases, small inflatable boats and RIBs, under 15ft or 4.5m, work with a short shaft Spirit 1.0 or Navy 3.0 / 6.0. Meanwhile, Spirit 1.0 is very popular with one-design racing sailboats under 26ft, like J70, Melges 24 and SB20. Sailors can make the decision according to the height of the outboard mount bracket.
Please note that Spirit 1.0 has an extra short shaft version (52.5cm or 20.7 in). It’s designed for shallow water areas and very small boats. The Navy series doesn’t have the extra short shaft version.
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 leave a message to our official Facebook.