材料： The 4，426gt Swedish vessel Skagern sailed for her next port，Strood，with a draught of 5.95m．The master soon realized，however，that he would not make the tide for berthing if he proceeded to the Medway as planned，to pick up the pilot at the North East Spit．He therefore decided to change the passage plan by shortening the distance and embarking his pilot at the Sunk light vessel．The officer on watch，2/O，was told to make the necessary adjustments and lay off the new courses． The 2/O made the original plan based on waypoints calculated and entered by another officer．These had been marked on the various charts and had already been entered into the GPS navigator．When he amended the passage plan he used the GPS to calculate a new course from a waypoint off Lowestoft direct to the Sunk pilot station．In doing so，he didn&39;t realize he had missed out a pre-programmed waypoint in the GPS for a position to the east of the East Shipwash buoy．He didn&39;t notice that his course line intersected the 5m depth contour to the west of the East Shipwash buoy． The master did not check the amended passage plan and Skagern continued with her passage．2/O came on watch again four hours before the vessel was due to arrive at the pilot station．One hour before arrival at the Sunk 2/O prepared to embark the pilot． He saw the North Shipwash buoy and passed about three cables to the east of it．Shortly afterwards he saw two more buoys ahead of him，the East Shipwash on his port bow and the North-West Shipwash on his starboard.It did not occur to him that anything might be wrong．Shortly afterwards，Skagern ran aground at a full speed of 14 knots．He had found the Shipwash Bank．