NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Role of CN at sea, was Re: Averaging sights ...
From: Nels Tomlinson
Date: 2004 Oct 12, 22:34 -0800
From: Nels Tomlinson
Date: 2004 Oct 12, 22:34 -0800
Well, what I really meant was: has anyone heard of a boat loosing or breaking all of its receivers? At 5 to 10 knots, loosing the signal for a quarter hour or so shouldn't be a big deal, but loosing all the GPSs to a lightning strike, simple failure or some series of accidents could be a big deal, and it seems as if it's bound to happen sometime. Nels On Tue, 12 Oct 2004 19:15:25 -0500, Billwrote: > > Has anyone ever heard of a vessel loosing all of its GPSs while at > > sea? If it hasn't happened yet, I suspect it will. > > In approx.. 700 hours of land and water operation over the past 3 years, I > have experienced five loss-of-satellites-signal situations, usually lasting > from 5-15 minutes. Three were on land, one due to a detour through the > mountains in Pennsylvania after a 50 car/truck pile up in front of me. With > mountains on all horizons and a blinding snowstorm overhead, would hardly > blame that on the system or unit. > > The other two land situations I have no explanation for. Great weather, > flatlands, no military bases nearby. > > Of the two on water (Lake Michigan) all units (my Garmin 76, an older > Magellan, and the owners chartplotter) all failed to get adequate signals > for 10 minutes or so. Partly cloudy sky. In one case an older Garmin showed > our speed-over-ground on a broad reach in a 34' Catalina as 33.8 kn. Not > too shabby--lucky the rudder stayed attached ;-) > > I have seen people sit on their unit left on the cockpit cushion and it lost > all of its waypoints. A friend's older Magellan unit failed to find > satellites after 3 hours. It is been replaced by a new unit. Have also > seen two different Loran C units go haywire, with errors of more than 5' lat > and lon. > > In talking with about a dozen sailors on the 600 dock at Michigan City, each > and every one of them has experienced unexplainable signal loss of 5-15 > minutes while on the water. > > Perhaps the Great Lakes don't meet the definition of "at sea," and is mostly > coastal piloting, but there is ample evidence a single unit can malfunction, > and even with multiple units, there are periods where signals cannot be > received. > > Not a big deal on the southern half of Lake Michigan where it is pretty much > point-and-shoot, but uncomfortable in the area where Michigan, Huron, and > Superior merge. > > Bill >