18 May, 2000
Ice Trial Reports
May 18, 2000
Daily Data (20:30):
Heading 190.633 deg
Air Temp. 4.05C 39.29 F
True Wind Dir. 191 deg
True Wind Speed 30 knots
USCGC Healy Facts: Mission Description
to function as a world-class high latitude research platform
to be employed in icebreaking operations during all seasons in the Arctic and Antarctic (designed for extended winter operations including intentional wintering over)
Phase 3, Leg 2 of the USCGC Healy's Ice Trials is quickly coming to a close. It now appears that we will arrive at our port of call, St. John's, Newfoundland, Canada, earlier than first anticipated. We are due to arrive sometime tomorrow afternoon or evening.
At our Healy-wide science meeting tonight, project reports were presented. Terry Tucker, Co-Chief scientist of this phase of the ship's ice trial studies, U.S. Army Cold Regions Research and Engineering Laboratory (CRREL), Hanover, NH, gave me permission to share the following excerpt from his report with you.
The ice trial of the USCGC Healy provides an excellent example of cooperation between the Canadian Ice Service, the US National Ice Center, the US Coast Guard, and the international group of scientists measuring the ship performance. With exception of the multi-year floe and first year ridge, most tests required finding suitably large areas of level first year ice.
From RadarSat imagery received and processed on the Canadian Ice Service (CIS) IceVu system, the Healy ice team identified potential testing sites based on floe size and roughness estimated from the radar backscatter brightness. Members of the ice team then reconnoitered the floes with the helicopter, measured their thicknesses, and designated them as suitable or not. The ice team then used RadarSat and Defense Meteorological Satellite Program-Optical Line Scanner (DMSP-OLS) imagery along with helicopter reconnaissance information to assist in routing the ship to the site.
Once on site, the ship normally penetrated into the floe a single ship length. At this point, a core was taken and its temperature measured to document the properties of the floe, and to confirm the thickness as measured from the helicopter. The ship then proceeded to run a variety of tests in the floe with the length of the run dictated by the amount of level ice available. The ship usually stopped at the end of the run at which time the ice team was placed on the ice to profile thickness and snow depth beside the broken ice track.
Thicknesses were measured at 5m intervals with the EM-31 electromagnetic induction instrument towed across the ice surface in a kayak and by drilling holes every 50 to 100m. On board the ship, the ice core was processed by cutting it into 10 cm. long sections whose diameter and length were measured and weighed. Thick sections were sliced off the samples for documentation of the crystal structure. Samples were then melted and salinity was measured. Brine volume and flexural strength were calculated from standard equations. The EM-31 measurements were converted to ice thicknesses using the drill hole measurements for calibration. A helicopter reconnaissance mission was often launched after the on-ice measurements to located the next test area. Terry Tucker
Devinder S. Sodhi, U.S. Army Cold Regions Research and Engineering
Laboratory (CRREL), Hanover, NH, shares the following information from the
summary statements in his report this evening.
The icebreaking capability of USCGC Healy are better than her design values of breaking 4.5-ft thick, level ice at 3 knots at full power level of 30,000 HP. For ice thickness in the range of 135 and 140 cm (4.43 and 4.59 ft), she broke at speeds in the range of 4.66 and 5.68 knots at a power level below 30,000 HP. She also broke 360-cm thick (11.8 ft thick) multi-year ice as well as one first-year ridge by backing and ramming. Devinder S. Sodhi.
For further information, please refer to my journal entries of May 6, 2000 "Profiling Ice Thickness"; May 7, 2000 "Determining Ice Strength"; May 9, 2000 "Multi-year Ice and Progress Summary"; and May 11, 2000 "Level Ice Trials."
The scientists and crew appear to be very pleased with the success of the Healy's ice trials and the data collected. The Healy not only exceeds design specifications, but also has exceptional maneuverability and performance characteristics.
Data on ice core 7A of April 14, 2000 follows.
Core 7A level ice 0414, End of Start-Up Test
14-April-00 Total length 68 cm
Latitude 63 deg 16.59 min
Longitude 62 deg 14.78 min
Comments: chips at 55 cm during processing core
Brine volume for -2>T>-22.9
Brine volume coefficients:
F1(T) COEF. -4.732 -22.450 -0.640 -0.011
F2(T) COEF. 8.90E-02 -0.018 -0.001 0.000
average brine vol 0.0645
average strength mpa 0.395
average strength psi 57.3
April M. Metz
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