It's a question on my exercises and I'm not sure of the full answer.

If I use the centre of a compass rose as my waypoint, I can read off it
constantly from my GPS.

If a reading is 098T, distance 1.2m , as in the question then

I am the reciprocal of that ? right ?
Or do I have to account for variation from GPS to chart? or is that a red
herring?

I hate these questions - I always tie myself in knots suspecting a trip wire
in them and then I can't see straight.

thanks
Hoges in WA

Dear Hoges,

I am somewhat unclear as to what you are asking but...

Your GPS will tell you the course from your position to your waypoint so if
the waypoint is the compass rose center you would plot it as the reciprocal
of the course from the compass rose to your position. Easier still is to
continue the line from your position through the center of the rose and out
the other side to read the course from you to the rose. Do not forget to
adjust your gps to give you true bearings or to read the magnetic circle of
the rose. True to true or mag to mag.

Ansley Sawyer
SV Pacem

"Ansley W. Sawyer" wrote in message
...
Dear Hoges,

I am somewhat unclear as to what you are asking but...

Your GPS will tell you the course from your position to your waypoint so
if the waypoint is the compass rose center you would plot it as the
reciprocal of the course from the compass rose to your position. Easier
still is to continue the line from your position through the center of the
rose and out the other side to read the course from you to the rose. Do
not forget to adjust your gps to give you true bearings or to read the
magnetic circle of the rose. True to true or mag to mag.

Ansley Sawyer
SV Pacem

Thanks Ansley
I (think) I mean do I have to take account of TM when using GPS? I can do
the reciprocal easy enough but am I imagining things when I have to take
into account variation? Or is GPS TT on a chart?

Sorry if that's not clear - half way into a bottle of McLaren Vale port for
those familiar with South Australian fortifieds.

On Thu, 10 May 2007 11:33:04 GMT, "Hoges in WA"
wrote:

I am the reciprocal of that ? right ?
Or do I have to account for variation from GPS to chart? or is that a red
herring?

You stated that the bearing to the center of the compass rose was 98T,
i.e., 98 degrees relative to TRUE north. That means the bearing from
the compass rose looking out to your boat is the reciprocal, 278T. No
allowance for magnetic variation is required when dealing with (T)rue
bearings.

Most GPS units can be setup to give headings and bearings in either
(T)rue or (M)agnetic degrees. Which one you use is mostly a matter of
personal preference but you must be consistent.

"Wayne.B" wrote in message
...
On Thu, 10 May 2007 11:33:04 GMT, "Hoges in WA"
wrote:

I am the reciprocal of that ? right ?
Or do I have to account for variation from GPS to chart? or is that a red
herring?

You stated that the bearing to the center of the compass rose was 98T,
i.e., 98 degrees relative to TRUE north. That means the bearing from
the compass rose looking out to your boat is the reciprocal, 278T. No
allowance for magnetic variation is required when dealing with (T)rue
bearings.

Most GPS units can be setup to give headings and bearings in either
(T)rue or (M)agnetic degrees. Which one you use is mostly a matter of
personal preference but you must be consistent.


Thanks Wayne.
Bottle almost gone but I'm not in charge of a vehicle or on a vessel.
I think I look for traps where there are none when I'm dealing with
examiners.
Part of being educated by Servite Priests (one step below Jesuits in my
opinion when it comes to devious)

Dear Hoges,

I envy you the port.

Just make sure that your gps is set up to give you true courses. Go into the
setup menus and turn off the automatic variation setting and make sure that
the manual variation setting is set to zero. The gps will then read true.

Ansley Sawyer

Hoges in WA wrote:
"Wayne.B" wrote in message
...
On Thu, 10 May 2007 11:33:04 GMT, "Hoges in WA"
wrote:

I am the reciprocal of that ? right ?
Or do I have to account for variation from GPS to chart? or is that
a red herring?

You stated that the bearing to the center of the compass rose was
98T, i.e., 98 degrees relative to TRUE north. That means the
bearing from the compass rose looking out to your boat is the
reciprocal, 278T. No allowance for magnetic variation is required
when dealing with (T)rue bearings.

Most GPS units can be setup to give headings and bearings in either
(T)rue or (M)agnetic degrees. Which one you use is mostly a matter
of personal preference but you must be consistent.


Thanks Wayne.
Bottle almost gone but I'm not in charge of a vehicle or on a vessel.
I think I look for traps where there are none when I'm dealing with
examiners.
Part of being educated by Servite Priests (one step below Jesuits in
my opinion when it comes to devious)

Lay the bottle on it's side and give it a spin, the neck will give you your
true course, so allow for variation.

"Dennis Pogson" wrote in message
...
Hoges in WA wrote:
"Wayne.B" wrote in message
...
On Thu, 10 May 2007 11:33:04 GMT, "Hoges in WA"
wrote:

I am the reciprocal of that ? right ?
Or do I have to account for variation from GPS to chart? or is that
a red herring?

You stated that the bearing to the center of the compass rose was
98T, i.e., 98 degrees relative to TRUE north. That means the
bearing from the compass rose looking out to your boat is the
reciprocal, 278T. No allowance for magnetic variation is required
when dealing with (T)rue bearings.

Most GPS units can be setup to give headings and bearings in either
(T)rue or (M)agnetic degrees. Which one you use is mostly a matter
of personal preference but you must be consistent.


Thanks Wayne.
Bottle almost gone but I'm not in charge of a vehicle or on a vessel.
I think I look for traps where there are none when I'm dealing with
examiners.
Part of being educated by Servite Priests (one step below Jesuits in
my opinion when it comes to devious)

Lay the bottle on it's side and give it a spin, the neck will give you
your
true course, so allow for variation.


Hadn't thought of that one. Will try it out. LOL