Re: Just curious about "wood" or "no wood"
another place you may find wood in a non-wooden boat is backing under the fiberglass (or aluminum, I'm guessing) surfaces such as the dash board or the deck (floor). This might not be structural but it's important.
Water can also get to the stringers if the glass encasing them gets stress cracks.
Fresh water rots wood far worse than salt water--we just don't see much of the rot problem except for a neglected boat with accumulated rain water. So if your boat drains, you can leave it out in the rain no problem. If it has a lot of upholstery, carpet or other water-trapping features, you can have issues. Boats can get wet; they just can't stay wet.
freezing adds to the dynamic--if the boat is dry, whether covered or draining properly, there's nothing to freeze. But the accumulated water, even in cracks and old screw holes, makes the holes/cracks bigger with freezing.
The floatation foam is not as bad as a sponge but it's not sealed cell either. I wish I knew why not. So it becomes a problem not if it gets wet, but if it's left in standing water. Picture a boat on a trailer with the plug left in, or one at a mooring without a bilge pump. That's the problem; not water from ordinary use that drains out like a little bilge water sloshing around during a day's skiiing. Along these lines, if there is a screw hole in the deck that constantly drips water onto the top of the foam, that won't drain and will become a problem
Don't forget that most transoms, like stringers, are wood enclosed in glass. Fresh water that gets in through a crack, loose fitting, unsealed screw hole will become a problem.