It's true, Jack. Wooden Minesweepers were non magnetic to avoid mines. Later, steel hulled ships had a degaussing ring around the waterline, to counteract magnetism. this is the same princple as erasing sound and video tapes. This is also why you don't lay your credit card on the rubber mat next to a cash register; it is magnetized to disarm those little plastic items attached to attractive items in stores. If you walk out and hear a beep at the door the clerk missed it. Nowadays they just clipp it off. Stan