Analysis of Ice Boom Design at Silver Bay Harbor

摘要

A series of safe harbors are being established along the north shore of Lake Superior from Duluth to Grand Portage, Minnesota. Violent storms can arise quickly in this part of the lake, and the rocky shoreline offers little in the way of natural protection to small craft. At the marinas, dock structures, which represent a major portion of the project cost are typically left in the water all winter, and therefore subject to ice damage. At the Silver Bay Marina, an ice boom designed to maintain an intact ice cover on the harbor and keep out wind-driven lake ice failed after just one season. This study investigated ice processes in Lake Superior as they relate to the design of the safe harbors. From the analysis, we concluded that constructing a boom capable of withstanding the expected ice and wave action along the north shore would be difficult and costly and, in the specific case of Silver Bay Marina with its southfacing entrance, the additional protection offered by the boom would probably not merit the expense.