Question about how a repair would be done

[ironmike]

Greetings all. I have a situation on my 1987 Cruisers Avante Vee that I have discovered a couple of weeks ago. I have set a goal this year to make the cabin 100% moisture free. So far, its been a challenge. It seems that I find a new leak every couple of weeks. At any rate, it appears that a shelf compartment under the captain's bench seat is the source a leak in the cabin. After further investigation, it appears that the shelving material inside the compartment has rotted. The compartment is a fiberglass enclosure which contains a shelf made out of plywood with a Formica overlay. Although the wood has not rotted completely, the wood is saturated and has started to peel in layers. I guess water is leaking somewhere in the area where the wood meets up against the fiberglass. I will post a picture so you can get a better idea of what I am attempting to describe. See the picture.

The area I am referring to is under the seat. Above the double windows is the shelving compartment. It is has two sliding smoked plexiglas panes.
My question is how would something like this be repaired? I realize the wood would be replaced but I was thinking that the fiberglass compartment would have to be cut in order to allow access to replace the wood shelf. If this is the case, where would be the best location to cut the compartment? Once it was cut, would the cut piece be used to fabricate the compartment back together or would it be rebuilt using new fiberglass? Thanks in advance for you response.

 

[Shadowcruzr]

Go in thru the overhead in the space under the shelf. Pull down the headliner and remove the shelf

 

[Goat Locker]

Without a picture it is hard to tell but if this is not a structural piece could it be two smaller pieces either length wise or front to back put in then covered with formica? I cannot believe that anyone would build a shelf that you cannot remove without cutting open the enclosure.