Toboggans:

Two Grizzly toboggans (SM051 and SM053) were used by K042 primarily on the sea ice and generally gave few problems. SM051 and SM053 each travelled about 910 and 950 km respectively. The variator belts were changed once on SM053 and twice on SM051. The fuel filter was replaced on SM053 and had to be cleaned (only partly successful) on SM051. Only one new disposable filter was available from Scott Base. Two-stroke fuel was mixed at 35:1 in the field from bulk 44 and 12 gallon drums. Fuel was mixed in the field because some of our equipment required MOGAS only.

Toboggan SM051 was fitted with a precision odometer for surveying on the sea ice. We also installed a 12V plus via the back light to run the echosounder from the toboggan battery. We found this to be very convenient and saved carrying an extra battery specifically for the echosounder.

Daily maintenance of the toboggans included; checking gearbox oil, variator bolts and most importantly the running gear. The nyloc nuts on the running gear are liable to come loose with several days use. This can only be prevented by careful daily checks for which we used a ramp and snow pit at Butter Point.

The few mechanical problems we encountered with the toboggans are attributable to dirty fuel which appears to be a common problem for many field parties. Fuel contamination could be eliminated by:

1. Providing quality fuel containers which are less likely to rust internally. Plastic containers designed specifically for petrol would be a satisfactory alternative.
2. Providing drum pumps with fuel filters attached.
3. Providing sufficient new in line disposable filters for the toboggans. We estimate that these filters should be changed between 300 and 500 km. The dirty filters cannot be successfully cleaned in the field.

Routes and Sea Ice:

K042 followed bulldozed roads on the sea ice between Scott Base, Butter Pt and Marble Pt. We followed the surveyors inshore tracks between Marble Pt and Dunlop Island; deviating offshore to check sea ice conditions on the way to Cape Roberts and returned on the surveyors route which was quicker. Several seasons travel between Marble Pt and Cape Roberts have shown that the sea ice is generally better within 1 km page 20 of the coast. Some rough ice can be expected on the north side of Gneiss Pt around Dunlop Island, off the Debenham Glacier ice tongue and near Cape Roberts.

Ferrar Fjord this season contained about 30% rough ice up to 0.5 m high including multi-year sea ice plates and a snow cover about 100 mm thick. Travel was generally easy but slow. This is very different to the 1984-85 season when the Fjord contained very smooth ice, less than 10% rough ice without any "permanent" snow cover.

In New Harbour rough ice again occurred in the central harbour with much multi-year ice in Explorers Cove. The sea ice was generally smooth on the south side of the harbour near the Bowers Piedmont Glacier. We often travelled on the Piedmont between Butter Pt and Trig Herb when commuting into the Ferrar Fjord. This route was smooth, snow covered and without observed crevasses.

The sea ice offshore between Butter Pt and Cape Roberts was quite rough with ice block walls 3-4 m high in places. Several adjoining leads were found from Dunlop Island to Cape Roberts for travelling. However the route was circuitous in places.

The sea ice in Granite Harbour was very smooth on the south side and inner harbour. Low rough ice occurred in the central harbour and on the northern side.

Sea ice this season was about 3 m thick in Ferrar Fjord, New Harbour, 0.5 m thicker than in 1985. Sea ice in other parts of western McMurdo Sound seemed also to be thicker, and by a similar amount. The distribution of pressure ridges, rough and smooth ice, however, was similar to that observed previously.

Helo Operations:

No helo time was allocated to K042 however three flights involved K042 personnel which were charged to separate events. These flights were well coordinated by Peter Cresswell at Scott Base and enabled the planned tasks to be carried out successfully.

1. Scott Base → Butter Pt → Scott Base.

   (Pyne and Dawkings retrieve equipment from Butter Pt. Afternoon operation only).

2. Butter Pt → Seismic Drill site → Butter Pt (Pyne to photograph granite core at drill site, return with surveyors to Butter Pt. Full day operation).

3. Butter Pt → Cape Roberts

   (MacPherson and Kelly assist survey party helo operation).