Prediction of Vessel Icing

Abstract

Vessel icing from wave-generated spray is a severe hazard to expanded marine operations in high latitudes. Hardships in making observations during operations, combined with differences in vessel type and heading, have resulted in great variability in vessel icing observations for similar meteorological conditions. This has led to difficulties in development of quantitative forecast procedure. A categorical algorithm for relating vessel icing potential to wind speed, and air and sea temperatures is presented which seeks to minimize these difficulties. A set of 85 icing observations were collected for Alaskan waters from intermediate size vessels (20?75 m) during 1979 to 1983, and verified by interviews with the vessel operators and by comparison with National Weather Service analyses. Of the set of 85, 58 cases were open-ocean observations where the vessel was not heading downwind; 25% of this reduced set had icing rates in excess of 2.0 cm h?1. Icing rate nomenclature and predicted icing rates for a given set of meteorological parameters developed from this study, and recommended for operations, are similar to those developed by Soviet and Japanese authors, but are five times greater than those based on the classic study by Mertins. This disparity is probably related more to difference in data analysis than to real geographic differences in icing conditions.