Moving from fresh to salt water
There''s likely to be a bit more electrolysis potential in salt water, so check your zincs. Electrical connections that have worked fine may suddenly go bad because of salt getting into things and causing corrosion of connections and contacts. Leather chafing gear will also absorb the salt, and the crystals will speed its deterioration and that of other cloth or canvas items like dodgers and sailcovers.
That said, people do still enjoy sailing on salt water.