 Ancient mariners, realizing that shipworms were imprisoned in the wood of their ships, would sail far up river and remain in fresh water for a number of months to kill the shipworms.Experienced divers look for siphons that project from the wood or use sonic devices to estimate the extent of internal damage.Shipworm and gribble attacks can also be detected
by immersing untreated wood panels and destructively sampling them at monthly intervals.