water, water everywhere...
A common problem I've heard when someone compromises with a coastal cruiser offshore is water intrusion. Less sturdy openning portlights weep and drip when pounded with boarding seas. Over time, the constant moisture on the interior trashes cabinetry and other vulnerable surfaces, besides detracting from the whole experience. Some people even silicone their portlights shut when they head offshore.
Something else to consider is condensation produced on interior hull surfaces from cooler seawater and air tempertures. That would seem to call for insulation of the hull in cooler latitudes.
I haven't been in offshore conditions so these items are only from what I've read or heard from those who have. Surely someone else in the forum can speak directly to wet interior issues when it comes to the original construction of the vessel.
For my headstone:
If I'd only listened to those guys about that wing keel...