Full-scale tests of deicing with seawater

Abstract

Sea-spray icing is one of the major hazards for small- and medium-sized vessels in polar regions. Predominant anti- and deicing measures include prevention by heeding the weather forecasts and avoiding high-risk situations, protection by enclosing exposed and high-priority areas, manual ice removal by personnel, heat tracing and surplus heat. Energy is in limited supply on vessels, and alternative ways of ice protection are sought after. Seawater is readily available, and as evident from wave-washing, either naturally occurring or increased by provocative maneuvering, seawater can hold an efficient deicing capacity. This study contains knowledge gained from four separate full-scale deicing tests. Deicing is achieved during the field tests by utilizing the vessel’s external fire sprinkler systems and in one case a fire hose. To the author’s knowledge, no recent tests with deicing of vessels using flushing seawater have been performed, and this article is considered a first step towards evaluating the viability of the method. Targeted high-volume, low-pressure systems seem to be an effective method for deicing, particularly combined with favorable design. However, because of the risk of increased icing or freezing run-off the method is suitable for vessels and structures with sufficient run-off capabilities. Vessel safety can be improved by incorporating the proposed method.