MARS-Report: Paltry PPU position predictor


In darkness and with visibility further reduced to about 150m in fog, a container vessel was being brought to a tidal river berth under pilotage.

To monitor the vessel’s progress, the pilot had set up his portable pilotage unit (PPU). He had connected the rate-of-turn generator to the vessel’s pilot plug and had set a variable range marker on the radar with a radius of 0.5 nm. The PPU had a predictor that continually self-updated to display the vessel’s next six predicted positions at intervals of 30 seconds.

The pilot and the Master had exchanged their respective information; the passage plan, local traffic and berthing procedure (pilot) and the vessel’s condition and manoeuvring data (Master). The pilot increased the vessel’s speed in order to overcome cross-currents at the mouth of the river and then commenced a starboard turn to enter the river as normal. Soon, the vessel’s speed was about 16 knots. At this point, the Master was using the ECDIS located at the starboard conning position to monitor the vessel’s progress, while the OOW was using a paper chart.

At 2150, the pilot ordered half ahead. About two minutes later the pilot ordered 15 degrees of starboard helm to initiate the turn through the next bend in the river. He then used the predictor to assess the vessel’s rate of turn. Soon he ordered the rudder angle to be reduced to 10 degrees to starboard, then to 5 degrees and finally to midships.

At 2153:20 the vessel’s speed was near 14 knots and the rate of turn was about 25 degrees/minute to starboard. About a minute later, with the speed now 13 knots, the pilot cross-checked information from the PPU predictor with the radar. The radar information showed the vessel was not proceeding as indicated on the PPU so he ordered counter rudder to port and full ahead on the engine to stop the turn to starboard and correct the vessel’s position in the channel. This action was insufficient and the vessel grounded at 2156, within the navigable channel but in an area where silting had been reported and that the pilot knew was present. With the rising tide the team were able to re-float and dock the vessel about two hours later.

The official investigation found, among other things, that;