Proceedings Of The Marine

SUM 2015

Proceedings magazine is a communication tool for the Coast Guard's Marine Safety & Security Council. Each quarterly magazine focuses on a specific theme of interest to the marine industry.

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33 Summer 2015 Proceedings measure water level in real time and are tied into a system that produces daily email forecasts of river stage and veloc- ity at one-hour intervals, with a forecast horizon of 10 days. Pilots and terminal operators routinely use this data to time river transits and maximize loading. For example, per- sonnel operating draft-constrained ves- sels transiting the Columbia River have to adjust their loading and/or the time of their transit to allow for two feet of under-keel clearance on the river and three feet (rising tide) or four feet (fall- ing tide) of clearance on the Columbia River bar. At times, timing issues arise for out- bound transits for fully loaded dry bulk carriers that, in most circumstances, are required to transit the bar on a rising tide. An outbound voyage from Port- land to the river mouth will usually take between six to eight hours. To cross the bar on a rising tide, vessels leaving Port- land have to pass the low water point somewhere en route. In the middle of the deep-draft channel near Longview, this low water point can represent river stage levels within two feet of zero gauge even during the period of high river fow. In some cases, upbound tran- sits are able to avoid waiting for maxi- mum tide in this way; there are some draft-limited inbound vessels, such as gypsum carriers, that must time up- river transits carefully. It is estimated that using LOADMAX affects river tran- sit timing by about 10 percent (approxi- mately 400 vessel movements per year), and can reduce delays for these transits by about 60 minutes. 2 While LOADMAX facilitates depth/ risk management for ship movements, the Columbia River Pilots' Vessel Traffc Information System, also known as Transview 32 (TV32), is another critical navigation technol- ogy. TV32 displays information from all automatic identi- fcation system (AIS)-equipped vessels, with scaled icons based upon AIS broadcast; it tracks speed, heading, course over ground, estimated time of arrivals to various points, and predicts real-time vessel meeting/overtaking locations. Pilots display TV32 on their laptops as a real-time vessel traf- fc display that is connected through the vessel's AIS. TV32 information is broadcast via secure Internet connection to dispatch/vessel movement coordinators and other industry stakeholders to monitor vessel traffc, manage anchorages, and maintain maritime domain awareness. LOADMAX River Level Forecasting LOADMAX river level forecasting example. Graphic courtesy of the Port of Portland.

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