An Easy-to-Implement Model to Determine the Percentage of Wake Energy from a Vessel Reaching the Shoreline Open Access
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An Easy-to-Implement Model to Determine the Percentage of Wake Energy from a Vessel Reaching the Shoreline Across the country, cities are considering implementing or have implemented ferry service as a method of transportation. According to the U.S. Department of Transportation, there were nearly 119 million ferry passengers in the United States, with the largest number being in Washington State and New York. Some examples of large cities with significant ferry operations include San Francisco, CA; Seattle, WA; and New York, NY. Ferry service is expanding with the National Census of Ferry Operators (NCFO) surveys showing a 25% increase in the number of ferry riders in San Francisco from 2013 to 2015 and New York City proposing to add ten new ferry terminals and 19 new vessels to expand their service by 4.6 million trips.During the approval process of the San Francisco Ferry system expansion, the effect on the number of boats in the water way and potential for congestion as well as the safety of the ferries and other vessels in the area were considered (van Dorp, 2011). To address that question, a simulation model was created by van Dorp, Merrick, et. al, to estimate the current number of vessel interactions and estimate any potential increases in the number of vessel interactions that could be caused by the expansion. Another important consideration in the approval process is the environmental impacts that may be caused by the ferry service expansion, specifically the impacts on the shoreline caused by ship wake. The Environmental Impact Assessment considered as “Impact 3.11-6: Potential Impacts to Shoreline and Project Area Facilities from Wake Wash.” While the EIA concluded that “new and improved facilities would be designed to withstand wake wash impacts. Vessel would be operated to minimize wake and wake wash from vessel operations would not adversely affect existing facilities in the project area.” This shows that wake impacts are important in expansion and development of ferry systems. This research creates a model to measure the proportion of the maximum energy density of wake wash created by a ferry (or any vessel) that impacts the shoreline as a function of distance away from the sailing line of the vessel. This model was based on ship wake models developed in the 1960s and earlier, as well as theoretical calculations about the wake produced by a water disturbance developed by J.J. Stoker (1957) and ship-generated wave models developed by Sorensen (1973), among others. It was validated by using data sets from the Maryland Department of Natural Resources, Alaska Department of Fish and Game, and a California Dataset from the Journal of Waterways.