Yea, greases or lanolin keep the prop nice and clean, as long as you
don't use it. Get underway once and it's all gone. OTOH, I've heard
nothiing but good about Propspeed. One other thing that seems to
work... color your prop with a black Marks-A-Lot. Can't explain why,
but every time the local boat yard writes something on a hull with one,
it's totally free of growth when they pull the boat again!