"Roger Long" skrev i en meddelelse
...
Ah, so these are different formats of data groups and not variables as
I thought. The ST1000 needs the cross track error to follow a track
and it looks like it will get it from the GPRMB which my GPS does put
out.

The ST1000 manual isn't very clear but, reading between the lines, it
uses either input from a speed device or a default cruising speed set
in calibration to set a new course according to the cross track error.
This makes me think that it doesn't take the boat back to the track
but simply sets a new course directly to the waypoint.

Can anyone clairify this?
SNIP
--
Roger Long
Unfortunately, I'm not familiar with all the NMEA codes etc.

My comment is based on practical experience using a Raymarine autopilot
4000 controlling the tiller on a 34' sailboat. My experience is, that in
case of XTE, the pilot "tries pretty hard to get you back to the
original track" ... (not in 90 degrees toward the track though) ... but
still with a course towards the next waypoint. I'm not aware of the
specifik formula.

On my system it is possible to reset the XTE to zero, in which case, it
will make a new track to follow - i.e. from the actual position in a
straight line to the next waypoint.

If the system more or les automatic - i.e. without intervention - could
follow another track than the original you have planned, you might get
into trouble if the new track passes over a rock or other unpleasant
obstacles ...

I think that is the same argument/reason why the system - not without
your physical intervention/approval (push a button) - will turn to the
next waypont, when you are following a route.

--
Flemming Torp
Gimle - DEN61