T&T: NAV Mode and Autopilots

[Gil Johnson]

It must have been a senior moment, as I was thinking about a discussion about radar and overlay mode, not the obvious topic about Autopilots.

Gil

----- Original Message ----
From: Peter Bennett <peterbb4 at interchange.ubc.ca>
To: Gil Johnson <dogtrawler at yahoo.com>; trawlers-and-trawlering at lists.samurai.com
Sent: Sunday, December 2, 2007 9:56:40 PM
Subject: Re: T&T: NAV Mode and Autopilots



Thursday, November 29, 2007, 6:54:20 PM, Gil wrote:

GJ> Mark Said: Since I use my autopilot on Auto, this problem doesn't affect my boat's heading.

GJ> Reply:  Mark, your system may use compass heading data for its
GJ> AUTO Mode--not all do.  Some use CoG for
GJ> their AUTO Mode and will be affected by GPS data errors.

GJ> Gil

I think it is highly unlikely that any autopilot would use COG from
the GPS as a heading reference in Auto mode - I would expect Auto mode
to be the "original" stand-alone autopilot mode which would use the
compass sensor as the reference.

The GPS CoG is, as it says, the Course over Ground - the direction the
vessel has travelled in the past several seconds - this may be only
loosely related to the direction the vessel is currently pointed,
which is what the autopilot needs to know to steer the boat.


-- 
Peter Bennett, VE7CEI    Vancouver, B.C., Canada
Ennos 31 "Honeycomb"
GPS and NMEA info: http://vancouver-webpages.com/peter 
Vancouver Power Squadron: http://vancouver.powersquadron.ca


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