Faulty automatic pilot results in grounding

Lookout! Issue 35, June 2016

Repairs to the automatic pilot did not save a fisherman and his crew from grounding their trawler on a spit off a South Island coastline.

The skipper had conducted sea trials with the over-hauled automatic pilot, which had a new head unit, rudder sender unit, heading sensor, and remote control. Satisfied with the performance of the repaired system, the skipper and his crew headed out trawling off the West Coast.

They had been fishing for a few days when one night, after the trawl net had been hauled, the skipper decided to go to bed around midnight. Two crew were left in charge of stowing the remaining catch and navigating the vessel.

The 23-metre trawler was steaming at about three knots, broadly west-north-west, heading slightly away from land, with a spit to port. The weather was clear and calm with only light winds, and the tide was flowing in from the starboard side.

In the two hours between the skipper going to bed and the grounding, the leading hand left the deck to go to the wheelhouse three times – the last was 40–50 minutes before the incident. On the last of his three visits the vessel was still going about three knots and tracking away from land, which was about three nautical miles away.

When the vessel grounded, both crew members ran to the wheelhouse, waking the skipper on the way. The pilot alarm was sounding and an error message was displayed.

Powering the engine full astern was not enough to dislodge the hull. The skipper contacted authorities and the owner, and awaited a tow off the beach at high tide about 12 hours later.

It was established that the automatic pilot altered course by 90 degrees to port, after displaying an error message. The skipper and crew were already aware that the automatic pilot still routinely displayed error messages, even after the repairs.

They had been turning the system off and on to correct the issue. Crew had also experienced the automatic pilot altering course if they were slow in turning the unit off, but the skipper had not been made aware of this.

LOOKOUT! Points

  • This incident clearly demonstrates the importance of keeping a proper look out at all times.
  • All relevant factors must be considered when assessing what constitutes a proper lookout including: the weather and visibility, traffic density, proximity of any dangers to navigation, and the reliability of any important equipment or machinery used.
  • All essential equipment should be serviced by people with the right skills and experience. Alarms should always be taken seriously, and false alarms fixed properly.
  • Steps should be taken to ensure all crew are aware of any problems, or other information, that could affect the safety of the ship.

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