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Title: Ship navigation simulator study, Upper Mobile Bay Channel
Authors: United States. Army. Corps of Engineers. Mobile District.
Huval, C. J.
Keywords: Channel improvement
Mobile Bay
Port of Mobile
Upper Mobile Bay Channel
Ship simulator
Publisher: Hydraulics Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Miscellaneous paper (U.S. Army Engineer Waterways Experiment Station) ; HL-85-7.
Description: Miscellaneous Paper
Abstract: Mobile Harbor navigation channel presently can accommodate ship drafts up to the authorized channel depth of 40 ft, depending on tide levels, dredging overdraft amount, and rate of channel shoaling. Many of the larger dry bulk carriers , such as coal colliers, are entering or leaving Mobile Harbor in a light loaded condition. This makes the movement of cargo more expensive and lowers transportation efficiency that could be possible by fully utilizing the larger vessels and their economies of scale. The relatively narrow channel width of 400 ft causes navigation problems, especially in the upper Mobile Bay channel reach where overbank depths become very small. In addition, ship steering problems have been reported by pilots in the vicinity of the Arlington Channel and when meeting a docked ship at the McDuffie Island Coal Terminal. Mobile District is considering a plan to deepen and widen the Mobile Harbor navigation channel in phases to ultimately provide a 55- by 650-ft channel. The presently authorized Mobile Harbor Navigation Project does not include a turning basln in the lower part of Mobile River or the upper part of Mobile Bay. There is no provision for a safe anchorage area for deep-draft vessels while awaiting berths. A turning basin and an anchorage area in the upper bay region has been proposed by the District. This report presents the results of a navigation study conducted on the US Army Engineer Waterways Experiment Station (WES) Ship Simulator. The purpose of the study was to investigate navigation improvements due to channel widening in the upper bay area. The impact of the proposed anchorage area and turning basin was also investigated. The effect of channel depth increases on navigation conditions was investigated separately, and was not considered in this study. As a part of the investigation a reconnaissance trip aboard a typical bulk carrier was conducted to observe pilot maneuvers and to record the inbound ship transit with video tape equipment and still photographs. Special tests were conducted on the Mobile Bay scale model to record current patterns in the upper bay study region. The study area navigation channel was schematized on the simulator using available navigation charts and topographic maps, and the District furnished hydrographic survey data. Ebb tide current data from the physical model were used to give realistic inbound test conditions on the simulator. The simulator visual scene was created using the data recorded during the inbound ship transit, maps, and charts. The simulations consisted of a series of inbound base tests using a 63,000-dwt bulk carrier fully loaded to a draft of 36 ft in the present channel depth of 40 ft. The proposed turning basin, anchorage area, and widened channel (from 400 to 650 ft) was then schematized and another series of tests was conducted. A total of 32 tests were run with three WES engineer-pilots and one active Mobile Bay pllot. The tests by the active bay pilot were particularly important because they validated the simulator visual scene, the method of schematizing the channel, and the strong bank-suction and crosscurrent effects on ship handling in the study area. The study showed that careful pilot control was required to maneuver the simulated ship in the 400-ft wide channel in the upper bay reach. Antlclpating the ship response at the Arlington Channel and the docked ship was necessary to prevent ship grounding or collision. The 650-ft-widened channel, the anchorage area, and the turning basin increase the safety margin ln the upper bay reach by greatly decreasing the banksuction forces at Arlington Channel and the docked ship. The proposed project will provide greatly improved navigation conditions in the upper bay.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Miscellaneous Paper

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