11 May, 2000
Level Ice Trials
May 11, 2000
Daily Data (20:30):
Air Temp. -8.69C 16.36F
True Wind Dir. 320
True Wind Speed 5 knots
USCGC Healy Facts:
Boats-2 LCVPs (Landing Craft Vehicle Personnel), 2 RHIBs (Rigid Hull Inflatable Boats
Aviation-2 HH-65 helicopters, flight deck, hangar, helo workshop and storeroom, aviation office
Inuit Language Lesson from Stevie Audlakiak and James Qillaq: Kalatik (kaw lawk' too): Good to eat
Mamautuk (ma mak' too): Boil (as in boiled meat)
It's a cold and blustery morning with winds around 28 knots creating poor visibility. Due to the weather, we will not continue our work on the multi-year ice floe. We will steam southwest instead to search for a first year floe having level ice around 125 cm thick. A couple of helicopter reconnaissance flights will be launched to search for an appropriate floe and, if possible, leads to it. On route, the Healy's engineers will be testing the Bow Wash System.
What are the Level Ice Trials and why are we testing in level ice? This is the question I asked Devinder Sodhi, U.S. Army Cold Regions Research and Engineering Laboratory (CRREL), Hanover, NH. Dr. Sodhi tells me that we are testing in level ice because it has a fairly constant thickness. If the ice thickness varies, then the speed of the ship is affected. If the ice thickness is constant and the speed of the Healy remains stable, then the capabilities of the ship can be identified in terms of speed at a given power level for a specified ice thickness.
Level Ice Trials to date have been conducted in ice thicknesses ranging from 60 cm to 170 cm. Tests have occurred in ice 60 cm, 90 cm, 138 cm, and 170 cm thick. It is a question of power versus speed. The tests attempt to have the Healy maintain a constant power level in a parcticular ice thickness and then measure the ship's speed.
This is like driving a car and pushing the gas pedal at a constant level for differing inclines. The results are different speeds for different inclines. For example, let's suppose that a flat highway and a mountain road are both straight. Imagine driving on a flat highway or up a steep mountain road with your foot pushing the gas pedal to the floor. At full power, will your car move faster on a flat highway or climbing up the steep mountain road?
Thin ice could be compared to a small incline and thick ice could be compared to a steep incline. Under full power, the USCGC Healy travels at a speed of 12 knots in a 66-cm-thick ice sheet and 2.5 knots in an ice sheet that is 170-cm-thick. Similar to a flat highway, if there is no ice (open water), the Healy moves at a speed of about 17 knots under full power.
What does "full power" mean? It means that the throttle control is all the way up to number 10 and all 4 engines are running. It's like flooring the gas pedal in a car.
So far tests at full power, two thirds, one half, one third, one fourth, and very low power have been conducted. Because all data is preliminary, it is unavailable for distribution at this time.
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