Bronze is an alloy of copper, with tin typically as the main additive. Other elements such as phosphorus, manganese, aluminium or silicon can also be added.

Bronze is stronger and harder than any other common alloy except steel, but resists corrosion (especially seawater corrosion) and metal fatigue better.

Propellers and IPS drives can be made in bronze, but also other equipment such as compass housings, (where non-magnetic materials are required) and fittings where hard wear and corrosion free performance is required.

Painting propellers can slightly degrade the performance.  Barnacles on the other hand will degrade the performance considerably more than properly applied paint, so an antifouling paint is, on the whole, beneficial.

Many pleasure crafts are anchored for a large part of their time and therefore need some form of fouling deterrent.

The very high cavitation forces and turbulence that can be developed with propellers make them extremely difficult to paint effectively.