You should look at the USS Lucid in the US it's an old mine sweeping ship made entirely of wood, it was held together by brass screws and had aluminum ladders because it faced the same issue. It is currently being restored in California,(reply>), Wood is the more common material for such ships, at least until recently. Japan, owner of the world's largest minesweeper fleet, just started switching over a few years ago. With the decommissioning of the Osprey class, all of the United States minesweepers are wood (with GRP coating). Britain was a pioneer in using GRP in ships.