TOPIC: Mckeecraft water in hull cavity?

Working on a 72 Mckee 19' (brothers) and replacing transom drain sleeve. Removed sleeve and a few gals. of water ran out from the large hull cavities. Assume there is some rot issue going on low in the transom. Seems solid though we did reseal the upper plies of transom with epoxy.
Question is, should we put some inspection hatches in the floor to dry it out? It has a foam core hull and 2-3-4 inches of foam ( I assume)in the cavity. I am thinking one 6" Beckson below the floor boards to vent it.
The boat had some cracking in the side floors and water would have got in there.
Kind of nervous about seeing rotten would stringers if we cut the 6" hatch in.......but the type of core constuction seems so solid. Overall boat seems decent for age. Deck cracks appear to be from hard use rather than structual but am unsure.

Found little searching this forum and very thankful for any help.
thanks,
Paul in NH

The boat had some cracking in the side floors

thats generally an indication that the stringers have rotted out and the deck is flexing, as it progresses those cracks will often be on the outside of the hull in the same area

If rot has set in,drying it out is not going to make it go away.I would put a couple inspection hatches in her.Or you could get stuck in some rough seas and watch the hull crack in half as your trying to get back to port.Option one is much better than just hoping that it is not rotted out, right? As far as the transom try tapping all over.If still questionable then drill a couple 1/8-3/8 holes on the inside and see if the wood is dry that comes out.Put a pick in the hole and try and feel around to see of its hard or mush.IF good the reseal with 3m5200/4200 or similiar caulk.