Sealed flotation tanks and compartments should be ventilated with drain plugs.  Simply loosen the plugs whenever you store the boat to equalize air pressure in the tanks and to prevent moisture from condensing out of the trapped air.

These 1" drain plugs are very quick to install with one drilled hole. Drive in the screws (sold separately) with a dab of silicone beneath the flange to seal the plug.

Drain plugs are used to ventilate sealed compartments in the Annapolis Wherry, Chester Yawl, Eastport Pram, Skerry, Jimmy Skiff, Northeaster Dory, Passagemaker Dinghy, Oxford Shell, and Mill Creek kayaks, among other CLC designs.