Ship Superstructure Icing: Data Collection and Instrument Performance on USCGC MIDGETT Research Cruise

Abstract : Spray generated by the collision of a ship's bow with waves freezes on decks, bulkheads and ship's components. It is most common on smaller vessels, where it has been known to cause sinking, typically by capsizing. Superstructure icing may also reduce the operating efficiency or mission performance of larger vessels. The ability to predict the environmental conditions under which icing may occur, the location of icing on a vessel under those conditions, and the rate at which ice will accrete may allow vessels to avoid hazardous conditions or operate in a manner so as to minimize the accretion of ice. This report describes how spray delivery and superstructure icing were measured during a research cruise on the U.S. Coast Guard Cutter Midgett, operating in the Gulf of Alaska and Bering Sea in February-March 1990, to support the validation and calibration of a numerically based icing prediction model being developed for the U.S. Navy. This research cruise represents the first such measurements on a vessel significantly larger than fishing trawlers, the basis for prior work. Development of the instrumentation, its placement on the Midgett, and ancillary equipment used to supplement the principal measurements are discussed. Data collection and problems encountered in the process are covered extensively. Finally, measurement error is discussed, with conclusions drawn concerning corrections to the data and their validity.... Bering Sea, Coast Guard cutter, Icing, Measurement error, Bow spray, Cold regions, Instrumentation, Ship superstructure icing.