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.
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 centre of the propeller. For gas outboards, it’s measured from the top of the clamp bracket to the anti-ventilation plate.
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.
After that, you could choose the recommended shaft length based according to the transom height.
For most small dinghies and aluminium 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.
For boats with the transom height higher than 50 cm / 19.7 inches, a long shaft version is more suitable.