Large ships do not typically use brass propellers- only small craft like speedboats. Major ships used to use bronze- not the same as brass- but more recently mfgs going to steel. This is an area where the kit mfgs get it wrong. Do not follow their instructions calling for brass or gold color.
I do bronze by laying down a coat of copper, then a thin overcoat of brown. If I want it weathered, I do that with a wash of medium green.