United States Coast Guard

Hibernating Aids to Navigation – A use case in navigationally seasonal waterways

The US Coast Guard will install three lighted Physical AIS Aids to Navigation (AtoN) in Port Moller Alaska to lengthen the navigation season.  Port Moller hosts a fish cannery, and the two adjacent bays provide foul weather shelter for vessels operating along the north shore of the Alaskan Peninsula.  The winter navigation season in Port Moller is complicated by ice and the year-round unlighted buoys are often moved off station by ice driven by a 2-3 knot tidal current.

The “Hibernating AtoN” concept intends to improve the reliability of the physical buoys, extend the navigation season on both ends, and provide additional Virtual AIS-AtoN for vessels seeking shelter in the protected bays. 

Unfortunately, solar calculations for Port Moller prevent year-round operation of the lanterns and AIS signals.  Therefore, the AIS-AtoNs will use their internal GPS clock to manage the hibernating on/off sequence prescribed by our waterway managers. 

It is envisaged that these units will place themselves in hibernation on 1 December and reawaken on 1 March.  It is further expected that by reducing the extreme duty cycle on the batteries during the dark winter, the life cycle of the AtoNs will be increased to an expected eight-year service life.

By R David Lewald, Vice-Chair IALA-ARM Committee, U.S. Coast Guard

Rapporteur: Paul Ridgeway

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