"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

"Roger Long" wrote in
:

Any tips or experience interfacing and using one of these autopilots
with a GPS also appreciated.

--
Roger Long


The autopilot doesn't do the navigating. The chart plotter does the
navigating and sends out directional messages to the autopilot via the
network from its calculations taken from GPS position data. i.e. "We
want to go to this waypoint. We are headed in this direction, so we need
to turn the boat 48.5 degrees to starboard to head that way. Our course
over ground to the waypoint shows there is 1.8 knots of current trying to
drag us off course, so we need to subtract that from the boat heading.
Yo! Autopilot! Turn 44.5 degrees to starboard or I'll tell the captain
to replace you!" Autopilot, terrified of being turned into marine scrap,
comes about smartly 44 degrees to starboard, as measured on its compass
I'm convinced, causing an awful gybe because you got cheap and didn't buy
the network wind instrument so Chart Plotter could tell the slaves it
needed to gybe to the new course. The chart plotter makes constant
course corrections and tells the autopilot what to do to make it happen.

Autopilots aren't all that smart, if you haven't guessed that already.
All this is to force you to buy more boxes...GPS boxes...Chart Plotter
boxes...Speed boxes...Gyrocompass boxes...Compass boxes...Wind
boxes...etc. The more boxes, the more data. The more data, the smoother
that turn is because Chart Plotter and Autopilot can see their rate-of-
turn lots more often than waiting on the calculated ROT from the slow GPS
updates. The more boxes, of course, the more profits. Boats are full of
boxes...

Hope the gybe didn't pull apart the traveler that needs replacing....(c;

Larry
--
Democracy is when two wolves and a sheep vote on who's for dinner.
Liberty is when the sheep has his own gun.

"Larry" wrote in message
...
"Roger Long" wrote in
:

Any tips or experience interfacing and using one of these autopilots
with a GPS also appreciated.

--
Roger Long


The autopilot doesn't do the navigating. The chart plotter does the
navigating and sends out directional messages to the autopilot via the
network from its calculations taken from GPS position data. i.e. "We
want to go to this waypoint. We are headed in this direction, so we need
to turn the boat 48.5 degrees to starboard to head that way. Our course
over ground to the waypoint shows there is 1.8 knots of current trying to
drag us off course, so we need to subtract that from the boat heading.
Yo! Autopilot! Turn 44.5 degrees to starboard or I'll tell the captain
to replace you!" Autopilot, terrified of being turned into marine scrap,
comes about smartly 44 degrees to starboard, as measured on its compass
I'm convinced, causing an awful gybe because you got cheap and didn't buy
the network wind instrument so Chart Plotter could tell the slaves it
needed to gybe to the new course. The chart plotter makes constant
course corrections and tells the autopilot what to do to make it happen.

Autopilots aren't all that smart, if you haven't guessed that already.
All this is to force you to buy more boxes...GPS boxes...Chart Plotter
boxes...Speed boxes...Gyrocompass boxes...Compass boxes...Wind
boxes...etc. The more boxes, the more data. The more data, the smoother
that turn is because Chart Plotter and Autopilot can see their rate-of-
turn lots more often than waiting on the calculated ROT from the slow GPS
updates. The more boxes, of course, the more profits. Boats are full of
boxes...

Hope the gybe didn't pull apart the traveler that needs replacing....(c;

Larry
--
Democracy is when two wolves and a sheep vote on who's for dinner.
Liberty is when the sheep has his own gun.

I'm pretty much of the opinion that the only automated course correction on
a sailboat, under sail, should be "Steer To Wind." That doesn't insure that
you will go where you want to go, but it will help prevent the boat suddenly
deciding to tack or gybe because it reached a waypoint that you forgot
about. Of course, missing that waypoint turn might put you aground, but
under no circumstances should the boat be allowed to sail itself for any
length of time without supervision -- fall overboard and the boat continues
merrily along its way. I use my tillerpilot on Essie, but only with someone
keeping an eye on "Otto." If I'm singlehanding, I have a remote for "Otto"
that lets me make corrections from the foredeck.

KLC Lewis wrote:

I'm pretty much of the opinion that the only automated course
correction on a sailboat, under sail, should be "Steer To Wind."

All my steering under sail will be done by the Cape Horn windvane servo
pendulum. The small electronic unit will just tweak the servo shaft while
under power with the primary effort to turn the rudder provided by the
boat's motion, just as under sail.

--
Roger Long

Larry wrote:

The autopilot doesn't do the navigating.

That's not what the manual for the ST1000 says. The GPS can tell it the
bearing, distance, and track error. The ST1000 has a logic circuit to
resolve this into a new heading.

No chartplotter on my simple boat. Not enough room and power for all that
fancy stuff.

I'll only be using this under power as well. See other reply.

Enjoyed the rest of your post though.

--
Roger Long

"KLC Lewis" wrote in
et:

I'm pretty much of the opinion that the only automated course
correction on a sailboat, under sail, should be "Steer To Wind." That
doesn't insure that


Lionheart's Network Pilot (B&G) has 3 options...Steer to Network Wind
instrument's data, steer to the autopilot's compass or take instructions
from one of the chartplotters or The Cap'n.

I agree steering to wind is correct, ESPECIALLY at night sailing short
handed. We never let her go off by herself without someone on watch.
Most of her sailing controls come back into the cockpit under the
hardtop. Sticking to a waypoint course isn't practical in most sailing
situations we encounter. Sailing in the general direction of some
waypoint is nice, though...(c;

If anyone is in a hurry or has to "be somewhere" at a certain time,
please take a jet, not spoil it for the rest of us who are happy to get
there "some time this month". Thanks....

Beer - Check...Food - Check...Water - Check. Who cares who's first?

Larry
--
Democracy is when two wolves and a sheep vote on who's for dinner.
Liberty is when the sheep has his own gun.

"Roger Long" wrote in news:45c39114$0$1339
:

That's not what the manual for the ST1000 says. The GPS can tell it
the
bearing, distance, and track error. The ST1000 has a logic circuit to
resolve this into a new heading.



Like I said, the chartplotter tells it how to steer the boat. A GPS
receiver puts out lat/long/time and calculates course and speed if it has
a little display with a crumb line. You can tell the simple GPSes with
simple displays what waypoint lat/long you'd like to go to and it will
make a waypoint IT can steer the autopilot to. There's no way to input a
waypoint lat/long into the autopilot that has a few course change buttons
and simple controls. $GPAP data coming from the simplest GPS tell it
what to do:
$GPAPA - Autopilot Sentence "A"
$GPAPB - Autopilot Sentence "B"
$GPASD - Autopilot System Data
So, the little GPS you put the waypoint into is the chartplotter, whether
it has a $200 map plug into it or not.

The autopilot has no computing capacity to store waypoints, do great
circle calculations, etc. On your simple installation, I'd like to
recommend the Garmin 76Cx handheld GPS/Chartplotter in its little snapin
mount at your helm. Power is not an issue. It uses so little it will
still give you full navigation on its own batteries if yours fail. It
comes with America Recreational chart, but the CD has all the bigshot
charts you can load into its standard microSD 128MB memory card. The CD
program loads the 76Cx from your laptop, and you activate the charts you
want to BUY online for it.

Now you have a full-featured chartplotter to run the nav solutions and
tracking on that's really neat. I installed one on my buddy's sailboat,
and he also has a Jolly Boat (fiberglass rib boat with 40hp outboard).
We bought a second snap-in GPS mount for the Jolly runabout and you just
pop the 76Cx out of your pocket into whichever boat you're on and have a
full navigator, even on a boat with a 40hp Yamaha outboard....overkill?..
(c;

The little autopilots I know of only have a fluxgate compass to steer
with.

Larry
--
Democracy is when two wolves and a sheep vote on who's for dinner.
Liberty is when the sheep has his own gun.

Roger Long wrote:
Larry wrote:

The autopilot doesn't do the navigating.

That's not what the manual for the ST1000 says. The GPS can tell it the
bearing, distance, and track error. The ST1000 has a logic circuit to
resolve this into a new heading.

No chartplotter on my simple boat. Not enough room and power for all
that fancy stuff.

I'll only be using this under power as well. See other reply.

Enjoyed the rest of your post though.

You have a GPSMap 76. Doesn't that count as a chartplotter?

"Roger Long" wrote in message
...
KLC Lewis wrote:

I'm pretty much of the opinion that the only automated course
correction on a sailboat, under sail, should be "Steer To Wind."

All my steering under sail will be done by the Cape Horn windvane servo
pendulum. The small electronic unit will just tweak the servo shaft while
under power with the primary effort to turn the rudder provided by the
boat's motion, just as under sail.

--
Roger Long

Ya, Cape Horns are good units. I want to figure out how to add one to my
boat, but with my davits it's a bit difficult.

"Larry" wrote in message
...

I agree steering to wind is correct, ESPECIALLY at night sailing short
handed. We never let her go off by herself without someone on watch.
Most of her sailing controls come back into the cockpit under the
hardtop. Sticking to a waypoint course isn't practical in most sailing
situations we encounter. Sailing in the general direction of some
waypoint is nice, though...(c;

If anyone is in a hurry or has to "be somewhere" at a certain time,
please take a jet, not spoil it for the rest of us who are happy to get
there "some time this month". Thanks....

Beer - Check...Food - Check...Water - Check. Who cares who's first?

Larry
--
Democracy is when two wolves and a sheep vote on who's for dinner.
Liberty is when the sheep has his own gun.

I've charted-out my proposed route for my wee-long July cruise around the
northern end of Lake Michigan. In theory, it's seven days leaving Marinette
(home port), hitting Washington Island, Snail Shell Harbor at Fayette MI,
Manistique MI, St.James Harbor at Beaver Island, Leland MI, Stugeon Bay via
the Canal, and back to Marinette. In theory. I'll be gob-smacked if that's
where I actually get to go.

Karin