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Steering clear of commercial ships

A new collision-avoidance system tracks and displays ships on your computer, chart plotter or radar

An 800-foot freighter was making its way through heavy fog on Puget Sound 10 years ago last fall when the bow lookout spotted a boat at anchor dead ahead in the shipping channel.

The ship rammed the 34-foot wooden boat at 14 knots, picked it up on its bulbous bow, and carried it for 1-1/2 miles before finally dumping it in the water, a mangled wreck.

The couple aboard the boat survived the accident with just minor injuries. But Fred Pot — whose company, SeaCAS LLC of Kent, Wash., has developed an electronic collision-avoidance device for yachts — says the story underscores his mantra: “You don’t want to cross a shipping lane without one.”

Pot, 58, who has been deeply involved in government work groups helping implement the Automatic Identification System for ships, has developed AIS-based collision avoidance technology for yachts. His system tracks the locations of up to 100 nearby ships on a computer running AIS-compatible navigation software, or chart plotter or radar displays. _The system also gives such information as their course and speed; heading and rate of turn; length, beam and draft; and their closest point of approach to the boat and time of closest approach.

Pot says it is all good information to have because big ships can neither stop quickly nor turn on a dime. “The ships are 5,000 times as big,” he says. “It’s impossible for them to make avoidance maneuvers. The responsibility is on the boater.”

Pot’s SafePassage AIS is designed for boats from 28 to 65 feet and includes an AIS receiver, antenna and GPS — all housed in a fiberglass tube that mounts on a standard antenna mount — signal converter and cables for connecting to a PC, Macintosh, chart plotter or radar. It retails for $1,250.

What makes this collision avoidance technology available to recreational boaters is the requirement — effective Jan. 1, 2005 — that nearly every commercial vessel larger than 65 feet carry AIS in U.S. waters. Shipboard AIS uses the ship’s VHF to transmit and receive navigation and other information ship-to-ship and ship-to-shore for purposes of collision avoidance, port traffic control and homeland security.

Pot says it makes sense to put an AIS receiver on board a yacht to capture that information and use it to help the skipper steer clear of ships. SafePassage receives AIS data from ships up to 30 miles away, and updates the navigation information every two to 10 seconds.

“There’s no monthly fee,” Pot says. “You just need a receiver to use this very valuable information. It really is helpful.”

Pot expects most navigation software and chart plotter manufacturers to offer AIS-compatible products soon and hopes that someday they will develop software that will use AIS data to warn boaters automatically when they are on a collision course with a ship.

“There are applications for AIS that we haven’t even thought about yet,” he says.

For more information, including a list of compatible software and hardware, visit