[Goob13]

Previous owner let the ski sit in the Ohio river for awhile and it's got this river scum on it. Not quite barnacles, but a sandy, gritty substance. Flakes off when scratched by a fingernail but that is not very efficient.

Is there a solvent that is safe to use? Will something like CLR work or will that harm the components?

 

[Goob13]

another angle

another angle

 

[barmanvarn]

I'm going to totally take a shot in the dark here....and i'm sure someone will correct me if this is a bad idea...

Looking at the deposits they remind me of the buildups you get on shower heads at home.

I'm thinking maybe a solution of CLR (Calcium Lime remover) in a spray bottel? Spray it on, let it soak for a bit, then hose off?

Just an idea.

 

[Ernest T]

I'd say barmanvarn is right. It looks like lime deposits. The CLR would probably work. Do a search for Hull cleaners and you will find many similar products, that usually have some type of mild acid to dissolve it away.