Bathymetric survey helps Cook Strait shipping
Bathymetric survey helps Cook Strait shipping
Bathymetric survey showing the rock pile, which was 1.8 m high and at a seafloor depth of around 14.6 m.
When a barge carrying rocks from Picton to Wellington turned turtle at the entrance to Wellington Harbour at 3.00 a.m. one Saturday recently, the Wellington harbourmaster called in NIWA to help.
The barge dumped around 300 tonnes of rock into the shipping channel, raising concerns that the rock pile would be a hazard to other vessels, especially in times of heavy swell.
NIWA’s survey vessel Pelorus was launched the following morning, and scientists John Mitchell and Kevin Mackay undertook a bathymetric survey to locate the exact position and size of the rock dump. Shipping was diverted in the meantime, but by mid afternoon the harbourmaster was able to remove the diversion, as NIWA’s data showed that the rock pile was not an immediate threat.
John Mitchell comments: "Surveying the harbour entrance, in the shipping channel and at the tail end of a strong southerly, was interesting to say the least – 3 metre swells and numerous ferries to avoid. We had completed a survey in Cook Strait a few days earlier so Pelorus was still partially set up, and the normal 15 hour mobilisation only took 3 hours – fortunate for all concerned."
No one was injured when the barge turned over, and the upturned barge was towed to Miramar Wharf and righted by a salvage company.
