Short, Long or Extra-Long Shaft? Getting Outboard Shaft Length Right

Shaft length is the single most common thing buyers get wrong when ordering an outboard online — and the good news is it takes two minutes with a tape measure to get it right.

Measure your transom

With the boat on the trailer, measure straight down from the top of the transom (where the motor clamps or bolts on) to the bottom of the hull. That measurement tells you which shaft you need:

• Short shaft (15") — transoms around 38–40 cm. Common on small tinnies, dinghies and inflatables.
• Long shaft (20") — transoms around 50 cm. The most common fit for Australian trailer boats.
• Extra-long shaft (25") — transoms around 63 cm, typical of larger offshore hulls and sailboats.

Why it matters

Too short and the propeller sits high, ventilating in chop and losing thrust. Too long and the lower unit drags in the water, costing speed and fuel and exposing the gearcase to strikes. The right length puts the cavitation plate roughly level with the bottom of the hull.

Check the model code

Manufacturers bake the shaft length into the model name — that is what letters like S, L, XL or UL in our product titles mean. Every motor in our range lists its shaft length clearly in the product name and specifications table.

If you are unsure, text a photo of your transom and its measurement to 0480 009 809 and we will confirm the right fit before you order.