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Victoria University Antarctic Research Expedition Science and Logistics Reports 1982-83: VUWAE 27

McMURDO SOUND SEDIMENT STUDIES (K5) PART I. SEA ICE PROGRAMME - A. Pyne

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McMURDO SOUND SEDIMENT STUDIES (K5) PART I. SEA ICE PROGRAMME - A. Pyne.

Narrative:

Field preparation at Scott Base.

Pyne and McLeod arrived at Scott Base on October 11 to find that the seafloor sampling Wannigan had already been removed from its cantago sledge. The cantago sledge was required to move Vanda rebuilding materials to Marble Pt prior to its use by K5. This gave us the opportunity to properly repair the runners of the Wannigan which had been badly damaged by forklift during a previous season. Two new runners were bolted through the floor and wall plates, and the wall access holes patched afterwards. This work took Pyne and MacLeod two complete days and was one of many unanticipated jobs.

The Wannigan and sledge were again modified to suit new equipment and procedures. The winch required a new fastening system on the sledge, and enlarged wire access hole and new observation hole in the side of the Wannigan. This season we intended to sleep in tents while using the Wannigan to operate the coring, seismic and lab equipment and for water melting and cooking. The "range hood" was shifted from the side to the end of the Wannigan near the Colman heater and a new primus bench was built and installed underneath.

We were very pleased to find most of our cargo at Scott Base upon our arrival. The toboggans allocated to K5 arrived from Christchurch on October 16 together with our new winch. The next phase of our work programme which involved the testing and use of this equipment, included calibrating a special high accuracy "Halda twinmaster" odometer for the toboggan. The calibration was done over a one kilometre straight section of the ice runway access road which was considered an ideal surface. On this surface the odometer repeatedly measured within 5m of the taped one kilometre.

The tide gauge was set up off Scott Base for 13 days for testing prior to our departure to the field. The instrument worked well for five days until ice crystals which grew on the steel wire going to the seafloor froze the wire to the bottom of the DFA filled pipe and prevented accurate measurement. The wire line was later substituted for monofilament line which did not suffer the same freezing problem.

An ice reconnaissance flight by helo was arranged for October 21 (afternoon) for Pyne, McLeod (K5) and the two K26 surveyors. The helo flew to Butter Pt, mapping ice conditions enroute and circling Trig Herb to check that the drum beacon erected the previous season had survived the winter winds. On landing at the Butter Pt hut two further drum beacons stored from the previous season were filled with sea ice then underslung to Mt Coleman and Hjorth Hill where they were erected. This completed the beacon erection programme in the New Harbour area started late the previous season. While on Hjorth Hill the helo left to refuel at Marble Pt and returned as we completed the erection of that beacon.

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Sea ice conditions were mapped along the coast from Cape Bernacchi to Cape Roberts. At Granite Harbour aerial photography of the Mackay Glacier tongue was attempted. Due to timing and altitude miscalculations the photographs did not provide the 40-60% overlap anticipated but gave good coverage. These photographs became invaluable in the field to help locate our sampling sites and lay out the movement monitoring poles. We were grateful that the Scott Base Information Officer found time to process and print the film and hope that an official system to rapidly process scientific photography at Scott Base be available in future years. After checking a surveying point at Cape Roberts the helo returned to McMurdo.

The sea ice reconnaissance gave extremely good information enabling us to decide on a route to Granite Harbour and for setting out the Butter Pt. seismic lines. Regretfully if more time were available it would have been well spent checking the extent of the ice crack off Cape Roberts.

A total of 18 days were spent at Scott Base preparing for the field. This period could have been shortened by a day or two if Macpherson and Paintain had not been required to sit exams in Antarctica as we felt obliged to let them use the evenings for study.

The drawing of explosives from the McMurdo magazine delayed us a further day. Late in the evening of October 31 after receiving the explosives we finally left Scott Base for Butter Pt., only 3 days behind schedule.

Field Work.

The travelling conditions on the sea ice to Butter Pt. were very good with the first significant rough ice encountered east of Butter Pt. This leg of the journey took 11 hours by D4. On the Bowers Piedmont at Butter Pt. a cache of our seismic equipment, seismic explosives, 7 × 44 gal DFA and 2 × 44 gal Mogas was left for our return in mid-November. The east-west seismic line was located and bulldozed and three sea ice movement survey beacons established during the next three days. Pat Tinnely (K26 surveyor) joined K5 from Vanda during this period and was responsible for surveying.

The next leg from Butter Pt to Cape Roberts took a total of 16 hours and was broken into two days. Rough ice extending east of Butter Pt to Cape Bernacchi was avoided by travelling east along our seismic line then towards Marble Pt., along the American fuel train road. Travelling conditions from Marble Pt. to Cape Roberts were very good about three kilometres off the coast. Rough ice extended along the coast eastwards of our route coming in close to the coast at Cape Roberts but was easily negotiated.

Two days were spent camped at Cape Roberts while we began bulldozing a seismic road due east from Cape Roberts. An active ice crack was encountered 3km out which was impassable by D4 and caused the planned sea ice based seismic programme in this area to be abandoned. Ice thickness at the crack was measured page 36 and a monitoring survey begun. (Results of this survey are presented in Scientific Achievements). Macpherson and Paintin sat their final exam while at Cape Roberts. The tide gauge was established in about 20m of water before we left to camp at the Mackay Glacier tongue.

The sea ice conditions in Granite Harbour provided good travelling. Snow cover was minimal on the first year ice which penetrated to the front of the Mackay Glacier. Second year and multiyear ice was encountered westwards of the glacier snout. The second year ice was extremely hard with a scalloped surface except on the abundant frozen meltpools. This ice required a considerable reduction in travelling speed for comfortable riding.

The period 9-17 November was spent working in Granite Harbour with our base camp near the glacier tongue. The first part of our programme was to begin a movement survey of the tongue. Two sets of poles were put in on the tongue and surveying control was established on the Flatiron and on the ridge west of Cuff Cape. The New Glacier was used as a toboggan route to get people and surveying equipment to the Flatiron and Cuff Cape. Some difficulties were encountered on the bare ice at the snout of this glacier. Minor crevasses at the steeper top of the glacier were easily crossed. This part of the programme took longer than expected because new survey control was required and the initial difficulties of walking on the abundantly crevassed Mackay Glacier tongue. At the end of this part of the programme the surveyors (K26) left us by snotrac, checking the tide gauge at Cape Roberts for its continuing operation enroute to Butter Pt.

During the remainder of the time at Granite Harbour two good seafloor cores were taken within a large accessible sea ice filled crack in the tongue and at the front of the glacier. Current measurements were made and bathymetry measurements attempted. An electronic problem with the newly acquired echo sounder resulted in few successful measurements but this problem was fixed later in the season at the Blue Glacier. The weather was extremely good at Granite Harbour during this time and no days were lost due to adverse weather.

The seismic programme required us to leave for Butter Pt. on November 18 reluctantly bringing to an end the oceanographic work in Granite Harbour.

The journey from Cape Roberts to the Butter Pt. seismic line took 15.5 hours. Two days were spent awaiting the arrival of Ray Dibble and part of the seismic line was reflagged in poor weather during this time. K26 joined us to resurvey the sea ice beacons on November 27.

The seismic programme at Butter Pt. was completed on November 28 when we moved to the Dailey Islands, meeting the Geophysics Division party led by Tim Stern (K7) and continued a seismic programme in this area. The journey took 8 hours by D4 and of this about 1 hour was spent extracting an obstinate cantago sledge from a recently formed 1.5m wide ice crack trending east from Butter Pt. The sledge was extracted without much difficulty and was at no time in danger of losing its load. A further to wide crack trending eastwards from the Stranded Moraines was easily crossed.

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The seismic programme at the Dailey Islands was completed on December 3. K7 and Dibble/Paintin returned to Scott Base. The next day while the remainder of K5 moved to the front of the Blue Glacier. A good seafloor core was obtained about 200m off the glacier front. We were joined by the Scott Base mechanics/science technician for a night while they replaced the engine on one of the Snotric toboggans, and examined the echo sounder.

The period December 7-9 was spent making bathymetry measurements from the Blue Glacier to Cape Chocolate, Cape Chocolate to Dailey Islands. Bathymetry measurements were also made at the shot points along the Dailey Islands seismic lines and along the McMurdo Ice Shelf front. A coring attempt near the Dailey Islands was only partially successful because of the compact sandy bottom.

K5 returned with the D4 to Scott Base on December 10.

Repairs were made to the toboggans enabling Macpherson and McLeod to set out for Explorers Cove in New Harbour 2 days later. At Explorers Cove they met the K26 surveyors and then moved to Butter Pt. to complete the final surveying of the sea ice movement beacons for this season. 3 days were lost owing to adverse weather. The Dailey Islands seismic lines were also surveyed before returning to Scott Base.

The "clean up operation" and return of equipment took just over a week. The sampling equipment required for the "Glacier operation" was prepared in readiness for February and left at Scott Base. Some minor damaged parts were returned to New Zealand for repair. During this period Pyne and Brian Smith set a series of explosions at the ice runway for K11. The explosions were intended to produce gravity waves which were recorded by K11 on the ice runway monitoring strain network. Bathymetry measurements were also made off Scott Base on a line to Mt Heine. The line extended 3km until depths greater than 560m could not be resolved.

During the period on the sea ice garbage was burned and the cans crushed by D4, bagged and returned to Scott Base for disposal. Human waste was deposited in augered holes in the sea ice.

Explosives

Explosives were drawn by K5 from both U.S. and N.Z. stock held in the McMurdo Station magazines, and controlled by the U.S. Navy. The explosives were used mainly for seismic shooting although a small quantity was required to remove a large pressure ridge on the west/east trending Butter Pt. seismic line and for Robin Holdsworth at the ice runway.

Drawn from McMurdo

17 cases "Vibrogel" (50 lb/case) )
)
3,000 ft Detonating cord ) U.S. Stock
100 Seismic detonators (100 ft leads) ) page 38
3 cases "Plastergel 75%" (25 kg/case) )
) N.Z. Stock
50 plain detonators )

Returned to Magazine as "N.Z. stock"

  • 3 cases "Vibrogel"
  • 1 2/3 cases "Plastergel 75%"
  • 1,000 ft Detonating cord (1 roll)
  • 40 plain detonators

Transport:

This season for the sea ice work K5 was allocated the D4 bulldozer which towed 2 "cantago" sledges (carrying Wannigan, equipment and fuel). 2 Snotric toboggans 037 and 036 (later replaced by 039) and two Tamworth sledges.

D4 Bulldozer.

The D4 was initially used this season for the fuel train and Vanda resupply to Marble Pt, and developed a fuel tank leak during this time. After returning to Scott Base the fuel tank was repaired, and the D4 given a general check and oil change by the Army Plant Operators and Malcolm McLeod before it was used by K5.

The only major problem with the D4 was the recurrence of the fuel tank leak in Granite Harbour. An attempt to replace the tank with a 44 gallon drum was not completely successful as vibration eventually sheared off the drum fittings and we reverted to the original tank. Over 4 gal/8 hours of DFA was collected from the leaking tank, while the D4 was stationary and idling. This contaminated fuel was used in the Wannigan heater.

The D4 was kept idling overnight and was only turned off intermittently during seismic recording. Average fuel and oil consumption for the field period is listed below:
DFA Machine under load 30 gal (Full tank) per 13-14 hours
Machine idling 5 gal per 12 hours
OIL Most oil used while idling 1 litre per 2 days
Hydraulic oil is used when operating the blade at about 1 litre every 8 hours. The leaks appear to be caused by scouring on the hydraulic rams.
Snotric Toboggans.

SM 037. This toboggan gave few problems in the field. Four bogey springs were replaced during normal use. A complete bogey assembly was damaged when the allen cap screw came out of the bogey axle. This was attributed to a page 39 faulty star washer and the bogey assembly was replaced. The Halda Twinmaster odometer was eadily fitted to the toboggan but was occasionally knocked because it could only be mounted in an exposed position.

The toboggan had a partial dunking in a frozen tide crack near the Mackay Glacier Tongue. Salt water entered the gear-box but was quickly removed by three successive oil changes and no starting problems occurred.

SM 036 was used for 3.5 weeks during which time only 4 bogey springs were replaced. While returning to camp down the New Glacier, the steering shaft sheared off where it attaches to the front ski. The remaining 7km to camp was negotiated with a person sitting on the front and steering with a length of rope and his feet. This toboggan was airlifted to Scott Base and replaced by SM 039.

SM 039 was airlifted from the lower Victoria Glacier, where it had been used by K1, to our camp in Granite Harbour. When it arrived we found the rubber sprockets on the right rear axle to be badly damaged and replaced the complete axle with our only spare. This machine was burning over 1/2 litre of oil per day unlike SM 037 and SM 036 which required only a small top up each week.

The engine on this machine "blew up" while carrying out critical seismic shots off Butter Pt. Piston, con rod and bearing were fragmented into several pieces. The engine was replaced with a new engine by the Scott Base mechanics while at the Blue Glacier five days later. The steering shaft also broke on 039 in the same manner as 036. On this occasion it occurred at a less critical time on flat sea ice one day before our scheduled return to Scott Base.

The distances travelled with each toboggan are listed below:

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Sledges.

This is the second season that Cantago sledges have been used on sea ice. On hard multiyear ice and bare firstyear ice the sledges tended to crab sideways which was partly due to a bent and therefore off-centre draw bar. The absence of any chain tensioning devices meant that this could not be corrected in the field. It became evident that loading is crucial to the sledges' performance because of the flexible deck but unfortunately it is not always possible to redistribute the loads daily. Modification of the skis to increase the surface area and rocker forward and aft is still necessary for rough ice and soft snow. Without these sledges however it would not have been possible to carry out our successful sea ice programme of the last two seasons.

The Tamworth sledges towed by toboggans were used to ferry our heavy sampling equipment on the sea ice near the Mackay Glacier Tongue and people on New Glacier. The older sledge fitted with keels was easily controlled and used on New Glacier requiring rope brakes only on parts of the downward journey. A new sledge without keels was extremely difficult to control fishtailing badly on sea ice. All the laminated bridges along the left side were cracked after work in Granite Harbour although the sledge was never rolled with a load on. How this occurred is still puzzling but it is most likely that a sideswipe with a heavy load (800 lb) may have caused the cracks. A new type of longer keel should be considered for Tamworth sledges which permanently protrudes under the ski and does not require a slot cut in the ski like the present adjustable keels.

Helicopters.

All 7 allocated helo hours were used this season. The sea ice reconnaissance to Granite Harbour and erecting beacons in New Harbour used 4.5 hours flying time and 1.5 hours ground time. The remaining 2.5 hours was used transferring 036 and 039 toboggans and flying urgently needed parts and surveyor to Granite Harbour.

Weather:

Good weather conditions dominated our field season on the sea ice particularly in Granite Harbour which appears to be sheltered from the McMurdo Sound southerly winds and snow. Only 5 days in total were unworkable all in the vicinity of Butter Pt. strong winds and blowing snow disrupted seismic work on two separate days (late November) and three days were unsuitable for surveying in mid-December.

Communications:

The VUW seismic party had 3 Compak radios with spare aerials and 5 spare batteries. Communication along the seismic lines on 4703 kHz was excellent page 41 until the seismographs were switched on. Interference from their power supplies was so great that 3m high aerial poles and high transmitter power were needed, and even then the shot instant signals were sometimes not good enough to start the Nimbus reliably. The frequent use flattened batteries in three days, and in the absence of helo resupplies batteries had to be recharged (slowly) from the 24V battery on the D4. A solar panel and voltage converter/regulator would be infinitely preferable!

Communications with Scott Base were generally good although long scheds were sometimes a nuisance if we had messages to pass and were also awaiting seismic shots.

VHF Radios.

We were again unfortunate not to be allocated VHF radios for our scientific work especially when surveying on the Mackay Glacier tongue. Mirrors can be used for very simple messages but they just do not work on cloudy days.

Recommendations:

1.Photographic Developing and Printing Facilities.

A photographic service (person and facilities) at Scott Base could be of considerable use for some scientific field parties. If a person at Scott Base were available to develop and print photographs many scientists could take photographs by helo on field party put-ins expecting prints to be available to work from a few days later in the field. Such a service would be useful for geology field mapping (where available aerial photography is unsuitable), surveying especially in the case of mobile features which change each year, e.g. calving ice tongues, and biological studies, e.g. seal and penguin census. The information officer might be a suitable person to provide this service. However, it would have to be recognised as part of his duties.

2.Explosives and storing Magazines.
A Scott Base explosives facility is becoming important as more field parties require explosives for their work. Two distinct problems are obvious:
(a)Temporary storage is required by parties planning to leave or returning from the field. The U.S. system cannot always provide explosives the day you require, or be able to take back explosives the day a field party may return to Scott Base. Field parties in transit through base also cannot store explosives for a day or so.
(b)The second problem is related to the 2 years advanced notice that the U.S. Navy system requires of New Zealand explosive requirements. New Zealand scientific programmes are only approved a year and a half in advance at the most so informing Antarctic Division of accurate requirements 2 years prior to use is impossible. If New Zealand had control of its own explosives this problem need not occur. However, until such time perhaps a "standing order" should be placed with the U.S. authorities.
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3.Dehydrated Food.

This season it was very disappointing to find much of the packaged dehydrated meals to be of lower standard than normal. It would appear to have been a bad batch and often was only suitable to make soup. The only field situations where "dehy" is essential is mid-summer in the dry valleys where temperatures are well above 0°C and where weight is vital, such as backpacking. Even on the sea ice in mid-December frozen meat can be kept below 0°C by adding snow/ice to a food box (fridge). I would like to see a change from the present "dehy" meals to an easier access to frozen meat for field parties requiring it and modern N.Z. "freeze-dried" meals for the rarer special situations.

4.Sea ice camping.

In December, tents, mattresses and sleeping bags often get very wet and salty when camping on bare sea ice making life miserable. Low camp stretchers that fit in a polar tent would prevent this and would be less bulky than the present foam mattresses. Waterproofing the present foam mattresses and PVC groundsheets may be a cheaper alternative.