Experimental study of ice accumulation on Arctic vessels and offshore structures

Bennett, Jonathan R. (2020) Experimental study of ice accumulation on Arctic vessels and offshore structures. Masters thesis, Memorial University of Newfoundland.

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Abstract

The arctic landscape has slowly been warming over the course of the 20th century resulting in a recession of ice coverage presenting ships with access and opportunity to regions previously blocked by heavy ice coverage and difficult weather conditions. A rise in global temperatures has accelerated the reduction of arctic sea ice coverage providing fishing and ships the ability to venture further north. Weather systems and frigid temperatures have historically overwhelmed ships traversing the arctic with heavy onboard ice accumulation risking the stability of the vessel and ultimately the safety of the crew. This onboard ice accretion is a combination of both ocean sea spray and freshwater precipitation and can additionally reduce the accessibility and functionality of essential mechanical and emergency equipment. The walkways, stairs and ladders can quickly become layered with ice making work and onboard navigation increasingly hazardous for the crew. While there are several methods to either prevent or remove accumulated ice, each is limited by either high costs, reductive efficiency or additional environmental concerns. Ship operators have traditionally relied on their crew to manually remove accumulated ice with shovels, baseball bats and sledgehammers putting the safety of the crew at risk as they work to remove ice on an already unsteady ocean surface. Additionally, they have generally avoided the thicker ice and colder environment of the winter choosing to work within the warmer summer months. However, with each passing year the ice coverage continues to shrink opening the arctic to more vessels and extending the shipping season further into the winter. This threat of marine icing is only going to become more extensive as the evolving arctic draws both the fishing and shipping industries further north in the pursuit of new opportunities. While there have been great advancements over the last half century in understanding the cause of marine icing there lacks insight and practical research into mitigating its onboard presence. The exposed stairways of ships are particularly dangerous as the increased slipping hazard is worsened with the risk of falling from a height or potentially overboard into the freezing arctic waters. This thesis gives a detailed look at the history of marine icing and the environmental properties which perpetuate its onboard growth. The research examines the effect of various stair design characteristics on reducing ice accumulation through a set of experiments conducted in the climate controlled cold room located at Memorial University. An open cell tread design resulted in the least amount of ice accretion when compared to the diamond plated aluminum, steel and rubber treads. Due to its hydrophobic properties the rubber tread accrued the most ice while simultaneously demonstrating the greatest ease of removal from impact testing. Thermal conductivity appears to have no correlation with ice accumulation or adhesion as both the steel and aluminum tests attained similar results with drastically different conductivities.

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