Nondestructive testing of wooden vessels

The Coast Guard is responsible for the safety of over 2000 wooden boats which are used as passenger vessels throughout the U.S. There is limited direction given to the Coast Guard inspectors within the Code of Federal Regulations and other documents so they must rely on their experience to assess the safety of the vessels. On December 5, 1993, the small passenger vessel El Toro II sank in the Chesapeake Bay with the loss of three people. As a result of the casualties, the National Transportation Safety Board made several recommendations to the Coast Guard and small passenger industry. One of these was that nondestructive inspection techniques for inspecting fasteners on wooden vessels should be investigated. This paper reports the results of a project at the Coast Guard R&D Center which has tested and identified some methods which may be utilized to improve the inspection of wooden vessels. In this project, previous work performed for inspection of wooden structures was reviewed and those which held the most promise were evaluated on a donated vessel. The test hull was then taken apart and the actual conditions compared to the test results. It appears that conventional and real-time X-rays can help inspectors determine the condition of vessels without causing damage. With some further development, two other techniques, SMARTHAMMER and CAPICIFLECTOR, have the potential of helping inspectors identify questionable areas.