A SINGLE screw may have caused the total write-off of a Scottish trawler, an official probe has revealed.
The Marine Accident Investigation Branch report said the 29-year-old Shalimar struck the quay wallat Scrabster in Caithness because the morse cable controlling the gearbox did not operate as intended.
This prevented the skipper from checking the vessel’s astern movement.
But the cable control did not work because a retaining bracket, which had been secured by only one screw, had detached from its supporting framework.
The report also said that the engines could not be stopped before the vessel struck the quay wall because they could only be halted from inside the engine room.
The vessel’s pumps could not cope with the flooding which spread quickly through the vessel as none of its internal bulkheads were watertight.
The wooden trawler sunk in just 23 minutes on April 30 and the MAIB said the evacuation of the vessel’s four crew to the quay was “timely.”
It made no recommendations over the accident which happened at 9.27pm and praised the actions of the 46-year-old skipper.
But it said: ”Changes to fishing vessel construction standards with regard to engine stops and watertight bulkheads should help to prevent new vessels from experiencing similar accidents in the future.”
There was no pollution and no injuries from the incident. The 23-metre vessel was re-floated 12 days later but it was beyond economical repair.
Shalimar sank after it made heavy contact with the quay wall when shifting berths in Scrabster.
The MAIB investigation determined that Shalimar’s skipper had been unable to stop the vessel’s movement astern because a morse cable, which controlled the main engine’s gearbox, had come away from its mounting in the wheelhouse.
“Factors contributing to the loss of control of the gearbox and the vessel’s foundering included: a retaining bracket used to secure the morse cable had been secured with only one screw, which had loosened over time,” said the report.
“In view of the difficulty in accessing the inner tapped hole due to the surrounding framework and cables, it is possible that only the outer screw had been fitted when the system was first installed.
The gearbox control cable had functioned correctly for many years, but it is evident that over time the single screw in the retaining bracket worked free from the supporting framework. As the screw was fitted without a locking washer, it had probably loosened due to vibration.
“It is also evident that the screw and bracket must have detached from the supporting framework immediately after the skipper put the engine ‘astern’ at 600rpm using the port control lever in the wheelhouse. Consequently, his subsequent movement of the control lever successfully increased the engine’s speed but did not alter the direction the gearbox was driving.
“When Shalimar’s skipper tried to check the vessel’s movement astern by moving the engine and control lever ‘ahead’, Shalimar’s stern was less than 30m from the quay wall. Therefore, at a speed of 4 knots, the skipper had approximately 15 seconds to identify that the vessel was not responding and take corrective action.
“In the circumstances, the skipper’s actions to try and secure a line ashore, increase the engine speed ahead, stop the engine and finally advise the port of the impending contact were positive and well-intended.
“If Shalimar had been built today, the current construction standards applicable to
wooden fishing vessels would have significantly increased the vessel’s survivability.
Consequently, no recommendations have been made.”
Shalimar’s skipper and the engineer, 48, were brothers and had been fishermen all their working lives. They had owned Shalimar since 1997.
The two deckhands were Filipino nationals and were employed on nine month contracts. Both deckhands were also experienced fishermen.
“In the circumstances, the early evacuation of the deckhands followed by the evacuation of the skipper and engineer after their unsuccessful attempt to control the flooding were appropriate. As the skipper and engineer had owned the vessel for 17 years, these were understandably difficult actions to take, but they possibly prevented serious injury or worse,” said the MAIB.