When the right propeller doesn't exist yet, we cast it.

What a custom job looks like

It starts the same way every Bruntons sizing does: engine power, rated RPM, gearbox reduction, shaft, and the boat's real numbers. Then the constraints that make it custom — aperture geometry, draft limits, nozzle or no nozzle, class rules, vibration history, whether the boat tows, trawls or just needs to be quiet.

Design happens in-house against blade-loading and cavitation limits; casting and machining happen in the same works that has cast propellers since 1908 — including a three-metre four-blade designed for quiet running on a fisheries research vessel, the largest wheel ever to leave the Sudbury foundry. You get a drawing before anything is poured.

Fixed props for working boats

For many motor vessels the honest answer is a well-designed fixed propeller — correctly sized, properly balanced, in the right material, built to classification-society standard where the survey demands it. Alloy choice is matched to the job: Nikalium and Superston, developed by the group's own metallurgists for maximum strength and corrosion resistance; high-tensile manganese bronze for general duty; stainless grades to order. We supply those too, and service or re-pitch existing wheels at the Queenscliff workshop.

For commercial operators the group also builds a controllable-pitch propeller (CPP) system that monitors vessel speed, load and sea state and sets pitch automatically — maximum power or maximum fuel efficiency, selected from the wheelhouse. Anything beyond 3 metres moves to sister company Stone Marine Propulsion, which designs up to the largest commercial vessels. And Bruntons' old habit of refusing orders it doesn't believe in applies here most of all.