[Rhodes22-list] Slim's Compass

David Walker david.walker5 at comcast.net
Thu Apr 7 12:38:16 EDT 2005


Ed,

GPS will give you course over ground which is in fact the direction the GPS
itself is moving (and hence only when it is moving). It doesn't make any
difference which way the unit is pointed.  There are new GPS "Compasses"
coming out with two GPS antennas spread over a baseline of a few feet that
will give you a static direction.  The neat thing about GPS is that
variation is accounted for automatically and there is no deviation.

I use a magnetic compass to steer by having chosen the course by information
from the GPS.  That way the magnetic compass is only giving me real time
relative feedback and the absolute heading value is not important.

Dave Walker
David Walker
David Walker Photography
davidwalkerphotography.com
----- Original Message -----
From: "Hank" <hnw555 at gmail.com>
To: "The Rhodes 22 mail list" <rhodes22-list at rhodes22.org>
Sent: Thursday, April 07, 2005 9:11 AM
Subject: Re: [Rhodes22-list] Slim's Compass


> Ed,
>
> It is true that the GPS tries to show a heading of where it is
> pointed, but I suspect it is deriving that from forward movement.
> Next time you go out, put the GPS perpendicular to your direction of
> travel for a few minutes and see what it shows for a heading.  I
> suspect it will be based upon your movement, not on where it is
> pointed.
>
> Hank
>
> On Apr 7, 2005 9:00 AM, ed kroposki <ekroposki at charter.net> wrote:
> >
> >
> > Slim:
> >        If you are going to keep the compass on the boat, then do a basic
> > calibration.  If your drive is paved, then get a cheap scout compass and
a
> > piece of chalk.  Plot N-S, E-W on the driveway, or street in front of
your
> > house.  Adjust the compass to N-S, then E-W, then S-N, then W-E and
again to
> > fine tune.
> >        The headings may not be perfect, but they will give you the
general
> > direction, so that you do not do Brad's trick of going in circles.  If
you
> > decide to do serious navigating then do more serious calibrations of the
> > compass.  Keep in mind it will never be perfect to a degree.
> >        As to which way do charts use, just look at a navigation chart in
> > the light.  The answer is usually somewhere on the chart in degrees.
> >        Bill said that a GPS is referenced from where you are coming
from.
> > On my Magellan Meridian, it tries to show a heading of where it is
pointed.
> > If you use a Meridian GPS, you should be able to calibrate the compass
to
> > within a few degrees.
> >        Are you planning a cruise across Lake Superior this summer?
> > Are you planning a visit to your mother's anytime soon?
> >
> > Ed K
> > Greenville, SC, USA
> > Addendum:  Navigators answer:   A number of different approaches are
being
> > tried. (We are still guessing at this point.)
> >
> > __________________________________________________
> > Use Rhodes22-list at rhodes22.org, Help? www.rhodes22.org/list
> >
> __________________________________________________
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