The Shetland Oil Disaster: Anchor system 'went unused'
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Your support makes all the difference.Braking systems for anchors of large tankers like the Braer, developed five years ago in Manchester, have not been fitted to a single vessel, the inventor claimed yesterday.
Keith Ridgway was paid by Shell to design an anchoring system to stop and manoeuvre bulk carriers following the grounding of Amoco Cadiz in France in 1978.
By 1987, Dr Ridgway's computer simulations had devised a hydraulic system of controlling the anchor chain. The Institute of Marine Engineers, Royal Institution of Naval Architects, Nautical Institute, and Lloyd's List of Shipping greeted the project as a plausible method of enabling a crippled ship to stop and moor.
Shell patented the design, but shipowners and marine legislators have baulked at fitting the system. Shell's own fleet has since been dispersed because of the commercial advantages of using ships sailing under flags of convenience.
'The Braer could have been stopped using the system,' Dr Ridgway, lecturer in mechanical engineering at Sheffield University, said. 'At the very least, she would have been slowed and manoeuvred so that tugs could take her in tow. As it was, she didn't even try dropping her anchor.'
The Braer's captain is expected to draw criticism for failing to obey the adage 'never run aground with an anchor in the pipe'. But modern tankers carry anchor handling equipment familiar to Victorian engineers. Under the huge pressures of a drifting tanker, either the anchor would break, or the chain snap at its last link with the ship - the derivation of the term 'the bitter end'.
Dr Ridgway's system increases the length of the anchor chain and controls tension on the chain by sensitive hydraulic motors.
Instead of the entire chain length being dropped, the hydraulics keep playing the chain out, then pulling it back as the vessel swings from having its beam (side) to the current. As the ship's bows turn to face the current, reducing the strain, the chain can be pulled in. The system can be likened to flying a kite, or reeling a fish.
'The system could be supplied by a specialist builder and simply bolted into place on the ship,' Dr Ridgway said. 'The cost for retro- fitting a super tanker with two anchors would be about pounds 280,000.'
'The simulation proved the system would work on supertankers like the Amoco Cadiz, which was three times bigger than the Braer.
'There has been absolutely no interest in the system. I thought insurance companies would be keen on the system, and offer reduced premiums to ships fitted with the system. If it had cut costs by reducing the number of crew, it would have been taken up.'
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