TANKER SPILLS, COLLISIONS AND GROUNDINGS

The basic finding is that collisions are a communication and coordination problem rather than a detection problem. In nearly head-on encounters, with the ships displaced slightly to starboard, the Rules of the Road are ambiguous and the ships are maneuvering into a collision. Almost all past groundings occurred either entering harbor or bays within a very few miles offshore. The data indicates that conning or guidance errors are as important as navigational errors in causing groundings and many of the conning-related groundings are connected with pilot transfers. An estimate was made of the traffic pattern in U.S. continental shelf waters. A comparison of this traffic pattern with the collision and grounding data showed no correlation between the level of tanker traffic and tanker casualties. Simplistic arguments relating tanker traffic and tanker casualties are not supported by the casualty data which indicate that local factors appear to dominate. Therefore, whatever vessel traffic management scheme is adapted should recognize this fact.