Under deck ventilation?

I picked up a 19' fiberglass skiff. The previous owner removed a "rotten" fiberglass deck and replaced it with plywood over new PT cross members. Other than the drain plug hole in the back, there is NO VENTILATION. I have kept the plug out over the winter. There is moisture collecting inside the hull that occasionally drips out the back. Should I be concerned? Should I add inspection plates that I can leave open under the tarp? Please advose.

 

Moisture, the proper temperatures and no ventilation are a death nails for wood. Ventilation is very important and yes, deck plates, open ended covers and the ability for air to move freely about the inside of the boat will help tremendously.

 

You get inspection ports in various sizes, not too expensive and the lid screws close. If you have one or two on the deck you could leave them open when out of the water.

Pity about the plywood though. Had it been an all glass or glass and foam you wouldn't have had a worry about it.

 

...so soon, but eventually yes..