Boat Propellers for Outboard Motors

Our Range of Boat Propellers

• • Yamaha. Aluminium props across Yamaha’s J, F, G, K and M series, from 9 1/4 x 9 3/4 for small tillers to 14 x 19 and 15 1/4 x 15 for V6 outboards. Props, shafts and spacers are also grouped in our Yamaha outboard propellers range.
  • Mercury and Mariner. Black Max aluminium props from 9 x 9 for small tillers, through 13 x 19 and 13 3/4 x 15 for 40 to 125hp, to 15 1/4 x 15 for bigger motors.
  • Johnson and Evinrude (OMC). Props from 9.9hp tillers through the 20 to 35hp and 40 to 75hp motors, V4s, and up to V6 and V8 motors, plus an OMC prop shaft while stocks last. With Evinrude production ended in 2020, these sit alongside the rest of our Johnson and Evinrude parts.
  • Suzuki, Honda and Tohatsu. Props for small and mid-range motors, including Honda’s BF35 to BF60 and Tohatsu’s 25 and 30hp outboards.

The props in this range are three-blade aluminium. Bushes, spacers, thrust washers and cotter pins are in propeller parts, and Mercury prop nuts are with our gear case parts.

Reading the Numbers on a Prop

Whatever the brand, a prop is sized diameter first, then pitch. A 14 x 19 prop has a 14 inch diameter and a 19 inch pitch. Diameter is the circle the blade tips trace. Pitch is the distance the prop would move forward in one revolution through a soft solid.

Water isn’t a soft solid, so the boat covers less ground than the pitch suggests. That gap is slip, and most setups run somewhere between 5 and 20 per cent. Our propeller pitch guide walks through the maths, with a calculator.

Choose Boat Motor Propellers by WOT RPM

Pitch sets where your engine runs at wide open throttle (WOT). More pitch lowers WOT RPM, less pitch raises it, and running outside the recommended WOT range can cause serious engine damage.

Each inch of pitch is worth roughly 150 to 200 RPM, and the right prop lets the engine reach the upper part of its WOT range. On a motor rated at 5,000 to 6,000 RPM, that’s about 5,700 to 6,000 RPM under an average to heavy load.

So test the boat loaded the way you normally run it: fuel, crew, gear and a full esky. If it tops out at 5,300 rpm on a 13 inch pitch, dropping to 11 inches should add roughly 300 to 400 rpm and put it around 5,600 to 5,700. If it hits the rev limiter, go up in pitch. Heavier loads call for lower pitch, so a prop that suits two people can leave a loaded boat struggling to plane.

Will It Fit? Spline, Gearcase and Hub

Matching diameter and pitch isn’t enough. The prop also has to suit the gearcase, the prop shaft spline and the hub system, which is why two props of the same size can be different part numbers.

• • Yamaha codes its aluminium props by series letter, matched to gearcase size: J for 9.9 to F20 tillers, F for the 3 inch gearcase on 20 to 30hp motors, G for the 3 1/2 inch gearcase on 25 to 60hp, K for the 4 1/4 inch gearcase on 50 to 130hp, and M for the V6 gearcase. The letter follows the size on the prop, so a 13 1/2 x 15 K only fits K-series motors.
  • Mercury Black Max props change spline count and hub with motor size: an 8-tooth spline on the 9 x 9 for 6 to 15hp motors, and a 15-tooth spline with a Flo-Torq II hub on the 40 to 125hp props.
  • OMC props for 20 to 35hp motors use a 14-spline shaft, while those for 40 to 75hp use 13 splines.

If you’re unsure, the part number on your old prop or your motor’s parts diagram settles it.

Aluminium or Stainless, Three Blades or Four

Aluminium is the low-cost, lightweight option. Stainless allows a thinner blade that’s more efficient and more durable. Performance drops as a prop wears, more so on aluminium props with light damage from bottom contact, so a dinged prop is costing you before it looks bad enough to replace.

Three-blade props are the most common. Four blades give more acceleration, at the cost of extra drag that can lower top speed. For heavy hulls that need to plane fully loaded, that trade is often worth it.

Hubs, Bushes and the Spun Hub

The hub is the link between the prop and the prop shaft, and it’s built to give way. When it does, you get a spun hub: you open the throttle, the engine revs hard and the boat barely moves, because the hub has let go inside the barrel.

Impact is the obvious cause. There are two others: older rubber hubs harden and slip, and exhaust heat breaks down the hub material. That heat can come from a worn water pump impeller or a clogged cooling system, so a hub that keeps failing is a reason to check the cooling side too.

Our prop bushes are listed by application, including Mercury and Mariner 35 to 225hp, Johnson and Evinrude 8 to 15hp and 150 to 250hp V6, and Yamaha 150 to 200hp. When you refit a prop, use a new cotter pin and refit the thrust washer and spacer in the order your parts diagram shows.

Matching Outboard Motor Propellers by Part Number

Start with the motor: model and serial number, then the parts diagram. Our Yamaha serial number lookup and Mercury serial number guide show where to find both.

Then search our range by the number on your old prop. Manufacturers revise props over the life of a motor and give the revised part a new number, and both Mercury and BRP have renumbered much of their range over the years. If your number doesn’t come up, send it to us and we’ll trace the current one.

Frequently Asked Questions

What size boat propeller do I need?

Start with the diameter and pitch stamped on your current prop, or the part number from your motor’s parts diagram. Then check it against the WOT RPM range in your owner’s manual with the boat normally loaded. If the engine can’t reach the upper part of that range, go down in pitch. If it over-revs, go up.

Why does my engine rev but the boat won’t move?

Usually a spun hub: the hub has let go inside the prop, so the shaft turns but the blades don’t push.

Do you stock props for older Johnson and Evinrude outboards?

Yes. OMC props from 9.9hp tillers up to V6 and V8 motors are listed by part number, along with OMC prop bushes and split pins.

How fast will my propeller ship?

Orders placed before 2pm Monday to Friday are dispatched the same day. Shipping is free on orders over $50, or you can collect from our Kunda Park warehouse on the Sunshine Coast, 9am to 3pm weekdays. Businesses can apply for a trade account.

Can’t find the boat motor propellers you need? Email online@victoryparts.com.au with your model and serial number, or call 07 5211 1675, and we’ll match the right prop.

This information is general in nature and doesn’t take your specific boat, motor or conditions into account. Always check your owner’s manual or the manufacturer’s specifications before fitting parts or doing maintenance, and talk to a qualified marine mechanic if you’re unsure. Not sure what fits? Email online@victoryparts.com.au with your engine model and we’ll help you find the right part.