Ferry’s thrust damages seabed

Press, 17 May 1984, Page 15

Ferry’s thrust damages seabed

PA Blenheim Propeller thrust from the newest Cook Strait ferry Arahura is causing severe slumping of the seabed below one of Picton’s ferry berths. Slumping around the boulders and concrete blocks at the rear of the berth was caused by the strong scouring forces from the ferry’s propellers, the Marlborough

Harbour Board committee was told. The harbour engineer, Mr Bob Taylor, said that about 100 tonnes of boulders would be placed on the seabed below the linkspan towers this month in an effort to alleviate the problem. The only real solution would be the installation of steel sheet piling. Slumping on the flanks was “very extensive due to the high water velocities at the level of the propellers,” he said. Mr Taylor said the propeller thrust from the Arahura was six times greater than that of the other ferries when the vessel was leaving the berth. The Harbourmaster, Captain Don Jamison, said the only other practical way of stopping the damage would be to tow the ferry away from the berth before allowing it to engage its propellers.

One board member, Mr Roy Johnson, said it was a wonder any part of the linkspan was still standing with so much damage being caused by the ferry.