HODSU takes to ice in Antarctica

LSHSO Aaron Godwin (HODSU), LSHSO Jaime Looten (HODSU), LCDR Mick Rigby (OIC HODSU), LSMT Peter Brown (CDT4), POHSM Rob Campbell (RAN Hydro School - HMAS Penguin).

By POHSM Rob Campbell

The Wollongong based Hydrographic Office Deployable Survey Unit (HODSU) departed Hobart on Jan 14 for a 10-day passage to Antarctica on MV Polar Bird for their summer survey program.

HODSU have been tasked with charting some of the northern and western approaches to Mawson Station in the event that ice closes the existing route through Kista Strait.

The trip down had unusually calm seas for the entire voyage. After a week, the first of many icebergs were sighted and a day out of Mawson Station, the ship approached the pack ice boundary. Two to three metre thick ice plates quickly replaced the open sea.

The Polar Bird (an Australian Antarctic Division resupply vessel) made easy work of the ice, arriving at Mawson Station on Jan 24.

This trip was historic in that she was transporting sections and parts for the Wind Turbine Project, a revolutionary engineering feat to harness the ferocious katabatic winds experienced at Mawson and turn them into electrical energy.

HODSU initially assisted with boatwork for the resupply effort.They used Polar Birds’s workboat to drive around the ship breaking up the reforming pack ice and moving it out of the harbour into Kista Strait so that the barges could continue to work ferrying supplies ashore in dropping temperatures.

The problem of refreezing pack ice was alleviated overnight when a large blizzard driven by 65 knot winds came through and cleared not only the ice in the harbour, but the surrounding survey area as well.

The area being surveyed was spectacular. The seabed comprised steep rock formations normally associated with glaciated landscapes, except on this occasion it was the seafloor that had U-shaped valleys, arretes (wall of ice) and pingos (small conical hill of ice). HODSU witnessed changes in depth ranging from 600m deep to within 2m of the surface within a few boat lengths.

Icebergs and ‘bergy bits’ littered the seas and penguins and seals were seen feeding offshore.

The average temperature has been -8C, with 30 knots of wind making it the wind chill factor -26C.

When HODSU first arrived, the hours of daylight lasted almost right round the clock with the sun setting for just a couple of hours early in the morning, making it difficult to adjust. The temperature of the water is -2C on average, so erecting a tide pole was quite a painful experience. Fortunately, the day the tide pole was inserted it had warmed to -1C, not though you’d notice!

With plenty to see inland from the Station HODSU managed to take a break from sounding and head up Mount Henderson in a Hagglund, a tracked snow vehicle. The view from the top of the ice plateau was the icebound coastline and out to sea for miles.

The round trip took 4 hours, an experience none of the HODSU team will ever forget.

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