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 minum sleds and wannigans whimsically named Empress, Frontenac, and Royal York (after three grand railway hotels in Canada). Graeme Dennison designed a lightweight fabric shelter that was manufactured in the HMC Dockyard sail loft out of double-layered nylon with batts of Dacron be- tween for insulation. An insulated floor completed the four- person shelter that included a kitchen box, space heater, and snow melter. A smaller shelter carried for emergencies was called the “instant igloo”; its two floor segments unfolded with the tent between them (somewhat like a bellows), and it could be set up in under a minute, even in wind.
Ships used for field trials included the Canadian Coast Guard ship (CCGS) John A. Macdonald and CCGS Labra- dor, Canada’s first icebreaker and the first warship to tran- sit the Northwest Passage (coincidentally, with 10 scientists from the DRB on board; Piggott, 2011). Through collabo- ration with American colleagues, the PNL team undertook the joint trial Polarpack 1 in 1962 to study sound transmis- sion between ice islands more than 1,000 km apart, and they sailed on the USS Staten Island during the Polarpack 3 trial in 1965. While embarked on icebreakers, they were frequently diverted from scientific work to assist ships in distress, pro- vide icebreaking escort services, or helicopter support. On one interesting diversion in 1967, the CCGS Labrador was diverted to the Eureka weather station to provide helicopter assistance to a joint National Geographic-US Wildlife Ser- vice project rounding up yearling musk oxen for relocation to Alaska (Milne, 1998).
Long-Term Under-Ice Measurements
Eventually, the PNL team wanted to design a recording sys- tem capable of being deployed in the Arctic for a year to mea- sure underwater ambient noise during freeze-up and under early winter ice. Over the relatively short period of 15 months between the initial concept and deployment, they designed and built the “Remote Instrument Package” (RIP) recording system that was customized in every way to long-term mea- surements in cold ocean waters (Ganton et al., 1970).
The RIP consisted of a square frame with two battery packs on opposite corners, the electronics package in the center, and a spherical DREA barium titanate hydrophone mount- ed above one corner. Digital recordings were made through a preamplifier followed by a bank of 6 one-octave analog fil- ters covering frequencies from 10 Hz to 16 kHz. The bands were sampled sequentially in time for an averaging period of four minutes, with timing provided by a Bulova mechani- cal timer. The skepticism surrounding the digital recording
Figure 5. Photo of the Remote Instrument Package (RIP) in Lancaster Sound, Baffin Bay, Nanavut, Canada, before it was raised to the surface. The hydrophone is in the cage at the top of the package. Batteries and electronics are in the pressure vessels. The winch carrying the recovery rope is visible at the back. Photo courtesy of Canada, Department of National De- fence.
system was evidenced by the inclusion of an independent analog system that recorded the 150- to 300-Hz band on a paper chart recorder. In fact, the digital tape recorder had mechanical problems when it was tested on delivery, but the short time frame for deployment required that the problems to be fixed in-house rather than waiting for procurement of a different recorder (Ganton et al., 1970).
The recovery system consisted of an explosive bolt that re- leased a custom-milled syntactic foam float that brought to the surface a light polypropylene line spliced into the wire recovery line. To assist in locating the float, there was a pop- up radio transmitter and a dye capsule that ejected bright green dye. An ingenious hook system to release the lines on deployment was devised so that the system could be low- ered into position. The RIP was protected from corrosion through the use of a zinc anode and liberal amounts of Vase- line. It was designed for deployment in up to 2,000 feet (610 m) of water and its mechanical components were designed for a lifetime of 2 years (Ganton et al., 1970).
In mid-August 1967, Milne, Ganton, Bill Burrows, and R. H. (Dick) Herlinveaux (of the Pacific Oceanographic Group) and their cargo were flown in an RCAF C-130 Hercules to meet the CCGS Labrador at Resolute, Nunavut, Canada. At each deployment location, bottom cores were taken to de- termine whether the bottom was hard enough to trigger the line release mechanism. The ship’s helicopter was sent to nearby shore locations where two rock cairns were built and portable radio transponders were placed to aid navigation on recovery. After each RIP was deployed, a photograph was
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