Buying a Sailboat from the Great Lakes
Freeze thaw period can be tought on a fresh water boat; when water enters areas that were not designed to be wet.
ie.: under deck fittings which have loosen, under normal use over time. This allows a little water to enter during the summer and then expanding over the winters. If gone un-notice, which is fairly normal, this cycle repeats it self year after year until it is to late.
When walking on a deck and one notices deflection or see brown water stains on the under side of the deck this boat is in need of a deck repair.
as for other areas of the boat on the plus side for "fresh water", I would think the be.
rigging, standing and running.
negitive side of fresh water,
poorly supported hull''s while in cradle,
hope this helps