sealant

Hey everyone! I just bought the jetski mentioned in the heading with 118 hours. I took a look under the bucket compartment by the battery, and there was a crack exposing styrofoam through the fibre glass in the front. I suspect this damage was from the anchor in the front compartment banging up...

I'm in the process of replacing wear ring and possibly impeller. I'd appreciate any comments on sealing around ride plate to help with cavitation. Also, at what point should I consider replacing impeller? I can already see it's a bit nicked up.

On my 09 150 Speedster I just removed the intake grate. The big bolt was pretty hard to get off with whatever sealant was installed. What is the proper sealant to use when reinstalling the bolt? Thanks