[wrectec]

I have had these deposits for several seasons. I wire brush them before put in and by hual out they are back. Senaca Lake N.Y. home port. CC alum Roamer. Any ideas??

[Garry Hartshorn]

Not familular with your area but would suggest it is calcium deposits from marine organisims not a big problem but can usually be resolved with antifouling which depending on usage wears of propeller tips quite quickly but will usually stay on the shaft and the hub of the prop.

[alloyed2sea]

Hmmm,..., could also be very slight electrical current differences generated by props vs. rudders vs. hulls - all connected to your shaft bones. Some folks use circular wire brushes on the shafts on the inside of the hull to "bond" them to the hull bone.
Anybody else got the details?