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Written by Helen Bostock (marine geologist, NIWA)

Date: 17/02/2013
Location: 65.627268°S, 144.277825°E
Weather: Cloudy, calm and very cold
Sea State: Calm

Over the last few days we have seen a lot of icebergs and have been skirting along the edge of the sea ice.

‘Patience….’ is the main advice of our Danish ice pilot, Arne Sorensen, when sailing the ship through areas with sea ice.

‘Slow and steady. The force of the impact if we hit the ice is related to the square of the speed that the ship is travelling at. So the faster you go, the more likely you will damage the ship.’

sea ice

Sea ice [Adrian Bass]

The RV Tangaroawas built in Bergen, Norway, in 1991. She is not an ice breaker. But she has an ice strengthened hull, and is an ice 1C class ship. This means that she can push her way through light ice floes of up to 0.4 m thick.Arne has been to Antarctica 20 times and the Arctic over a dozen times on a wide range of ships, with different missions. He has spent the last few years working specifically as an ice pilot, advising and training ship’s officers to negotiate icy conditions.Arne started going to sea when he was 16 years old as a cadet for a Danish shipping company. His father had been a sailor and then worked in the lighthouse, and his older brother was already working on ships. As a cadet he had to work on the deck, as well as learning how to be an officer. In Denmark they have compulsory national service: naturally, Arne spent his with the navy. After that he continued working on supply ships as a mate and then a Captain, and spent a couple of years working in eastern Greenland. Then he started coming down to Antarctica.

He says there are some differences between the sea ice in the Arctic and Antarctic. There is more multiyear ice in the Arctic (sea ice that hasn’t melted during the summer). First year ice has more salt in it and is “spongier”, while multiyear ice is harder and thicker.

Sea ice

Sea ice [Adrian Bass]

 In the Antarctic there are a lot more large icebergs, some of which get grounded on the shallow banks on the continental shelf. The icebergs affect the distribution of the sea ice. The east of an ice tongue, or ice berg, is usually iced up with “fast ice” (unlikely to break up and melt). This is due to the direction of the winds which transport ice from east to west. But you can’t assume that it will be the same every year, and the conditions can change very quickly.Arne is now retired. He chose to come on this voyage as he is interested in the science and still enjoys the challenge of navigating through the ice. “It is a balance between being cautious and trying to get the job done.”Evan Solly, the master, has been down to Antarctica 8 times, 7 times on the RV Tangaroa, while first mate Ian Popenhagen has been 6 times. So between them and the ice pilot they have 35 years of experience working in these icy conditions. Second mate Daniel Hayward, who is on his first trip to Antarctica, will benefit with expert training from them all.

Many of the crew have also been down to Antarctica before. Mike Steele, the bosun for the last 36 years, has been down many times. He is thankful for the improved clothing that they now have to cope with the extreme conditions, though he still isn’t completely satisfied with the gloves… Despite this, I feel we are in good hands.