FY 1989

Prediction of vessel icing: A 1989 update

Overland, J.E., and C.H. Pease

In Proceedings, 10th International Conference on Port and Ocean Engineering Under Arctic Conditions, Research Report TULEA 1989:08, Vol. 2, K.B.E. Axelsson and L.A. Fransson (eds.), Luleå University of Technology, Luleå, Sweden, 12–16 June 1989, 712–723 (1989)

The NOAA vessel icing algorithm is evaluated against theoretical advances. The most difficult factor is influence of sea temperature. Modeling demonstrates the importance of supercooling of spray during its trajectory to extreme ice accretion. This occurs when sea temperatures are less than 2-3°C above the saltwater freezing point. The sea surface temperature term in the NOAA algorithm is consistent with the supercooling hypothesis and a further category of "extreme" icing is added, which can explain anecdotal cases greater than 5 cm h. A wave height/wind speed threshold is 5 m s for a 15-m vessel, 10 m s for a 50-m large trawler and 15 m s for a 100-m vessel, developed from seakeeping theory. These wind speeds are exceeded 83%, 47% and 15% during February in the Bering Sea.