Dr. Bulman's paper (which is Crown copyright) was presented at an Institute meeting held in London on 19 February 1970 with the Hydrographer of the Navy, Rear Admiral G. S. Ritchie, C.B., D.S.C., in the Chair. The paper, which describes work undertaken by the Royal Radar Establishment on the measurement of ship movement for berthing very large vessels, was presented at the same time as the paper read by Mr. M. J. Tucker, National Institute of Oceanography, and the discussion relates to both.

When a 200,000-ton tanker hits a jetty at more than about 24 ft./min., that is, nearly a quarter of a knot, some damage is likely to be caused. However, the problem of measuring the speed of the ship starts much sooner than that. One could say that from the moment the log is retracted on entry to the estuary some other form of assistance ought to be made available. Traditionally pilots and masters have relied on visual estimation—on the appearance of the passing land and passing landmarks in order to judge the speed over the ground while travelling up an estuary. This has been adequate for smaller ships where the height of eye, length of ship, width of ship were all considerably less than they are now on the largest tankers, and where the critical velocities were higher. Now, however, it has proved very difficult to judge by eye the speed of a very large ship from a station some 80 ft.above the water to the accuracy required, the accuracy being of the order of ± 3 ft./min. It is in this spirit that the Esso Petroleum Company approached the Royal Radar Establishment (R.R.E.) some two years ago or so to tackle the problem.