Just out of interest: what would happen if there was something wrong with the hull and I sailed it? Would it slowly fill-up with sea water or fall to pieces?
how could I dry out the hull prior to test? the boat is stored outside without cover and the inspection cover on. Are we talking bucket and sponge?
Put the launching trolley about centre with the bows up in the air - then use a small container and then a sponge.
If the hulls seem solid, it is unlikely that anything is going to fall apart. There can be one very serious problem. There is a long foam block in the hulls running from the bows to the mainbeam. The hull skin must be bonded to this block or the hulls can split and fall apart. If you tap and press along the hulls between the bow and mainbeam, about half way between the keel and deck, it should feel very solid. If you feel the skin moving and stopping against something solid, then the bond is broken and the decks will have to come off and a new foam block fitted. It is a special block and con only be bought from the builders. Check out:
http://www.dart18.com/TechTalkBuyingUsed.htm