Re: [PSUBS-MAILIST] UW-DGPS

[Phil Nuytten <72020.572@compuserve.com>]

Hi, Suds:
        See my earlier post on GPS - we dont actually use underwater GPS
but take the ship's surface reading,link it to the sub tracking system, (
which tells you where the sub is, relative to the ship) and send the info
to the sub. The GPS info that the sub receives is inaccurate by 1.) the
anti-Hussein offset, which, I believe, is about 250 - 300 feet  unless from
military or NOAA. or Coast Guard vessel, and  2.) the distance the ship/sub
has moved since the info was received/sent. Still, a good pilot can get
back to a given spot pretty quick, once he is in that sort of proximity.
For absolutely accurate return, it's hard to beat a pinger, tho'  
Phil Nuytten