It's very important to make sure you have plenty of ventilation in all
areas under the seats and bunks etc. Make holes through each bulkhead
and have a few removable cover
plates somewhere handy to get at. Not only do these
removable cover plates allow you to use some extra space for storage but
when the boat is stored for any length of time the plates can be removed
to allow fresh air through the insides of all these dark places. Your
boat will breath better
and love you for it! ;-)