The Global Positioning System revolutionized maritime navigation when it was first introduced for civilian use in 1994. GPS navigation aboard ships provides the mariner with access to the benefits of real-time positioning data, not only by simplifying the navigation process, but by minimizing penalties for early or late arrivals in port.
A Guide for the Quartermaster
The directional guidance you see in your vehicle's GPS is delivered differently in the marine environment, where the only physical boundary is a shoreline. The quartermaster -- the person who steers the ship, under orders from the officer in command of the vessel, whether the master or the watch officer -- operates outside the constraints of a river bank or a harbor and is bound for a place several hundred or thousand miles away. In this environment, the GPS presents a direct line to the entered destination and a display, called the cross-track error, of the distance to travel that perfect course.
A Director for "Iron Mike"
On vessels not required to carry an inertial navigation system, which uses gyroscopes to detect the motions of the vessel, the GPS may be linked directly to "Iron Mike," the ship's autopilot. While the wheel is never left unattended, the autopilot attends to the task of steering on a long voyage, unless the ship's radar detects another vessel within 12 miles. When another vessel approaches, the officer of the watch may turn the autopilot off and have the quartermaster "put her on hand," or take the wheel. When the other vessel has passed and presents no danger, the autopilot is engaged again.
A Record of the Ship's Movement
The GPS aboard a ship, just like the GPS in a car, maintains a "track" of where the ship actually travels and transmits this information to shore, where it may be used to follow the ship's movements. Shippers, receivers, ship owners and national law enforcement authorities may use this information to keep track of a shipment of goods or -- in the case of law enforcement authorities -- the movement of a vessel seized by pirates.
A Device for Saving Money
Penalties exist in shipping contracts for cargo delivered late. Ports impose fees for vessels that arrive more than 1/2 hour early or leave more than 1/2 hour late because an untimely arrival or departure ties up their most important commodity: dock space. With guidance from the GPS, ships are able to notify the destination port of their arrival time accurately, minimizing costs to ship owners and managers who ultimately shoulder any loss because of a late delivery or an untimely arrival.
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