Autopilot NMEA question for gear heads
 

I just bought a Raymarine ST1000 Plus tiller autopilot for my Endeavour 32.
The astute among your will immediately wonder how this will work on a 13,000
pound 32 foot wheel driven boat. The unit will just drive the vane servo
shaft on the Cape Horn steering gear now on order. We could have bought even
a smaller tiller pilot if one was available.

Since I was trying to buy the smallest and cheapest unit I could get, I was
surprised to find out how sophisticated it is. Given the right NMEA input,
it evidently will follow a track to a waypoint instead of just blindly
maintaining a given course. It will even rollover to a new waypoint and run
another leg.

The Raymarine manual describes the inputs needed to follow a track but in
plain English. The Garmin manual for the GPSmap 76Cx I will be using says:

The following are the sentences for NMEA 0183, Version 3.01 output:

Approved sentences-

GPGCA

GPGLL

GPGSA

GPGSV

GPRMB

GPRMC

GPRTE

GPVTG

GPWPL

GPBOD

GPAPB

If anyone could annotate a quoted copy of this list I would appreciate it. I've
tried to find a listing via Google but the only one I can turn up is quickly
replaced by another page before I can read it. Presumably, the Capt'n wants
you to buy the information.

A link to a similar but readable listing would also help.

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

--
Roger Long

Autopilot NMEA question for gear heads
 

Never mind. I found a list at:

http://aprs.gids.nl/nmea/#allgp

I'd still be interested in hearing about anyone's experience with such a
hook up.

--
Roger Long

Autopilot NMEA question for gear heads
 

Roger Long wrote:
I just bought a Raymarine ST1000 Plus tiller autopilot for my Endeavour
32. The astute among your will immediately wonder how this will work on
a 13,000 pound 32 foot wheel driven boat. The unit will just drive the
vane servo shaft on the Cape Horn steering gear now on order. We could
have bought even a smaller tiller pilot if one was available.

Since I was trying to buy the smallest and cheapest unit I could get, I
was surprised to find out how sophisticated it is. Given the right NMEA
input, it evidently will follow a track to a waypoint instead of just
blindly maintaining a given course. It will even rollover to a new
waypoint and run another leg.

The Raymarine manual describes the inputs needed to follow a track but
in plain English. The Garmin manual for the GPSmap 76Cx I will be using
says:

The following are the sentences for NMEA 0183, Version 3.01 output:

Approved sentences-

GPGCA

GPGLL

GPGSA

GPGSV

GPRMB

GPRMC

GPRTE

GPVTG

GPWPL

GPBOD

GPAPB

If anyone could annotate a quoted copy of this list I would appreciate
it. I've tried to find a listing via Google but the only one I can turn
up is quickly replaced by another page before I can read it. Presumably,
the Capt'n wants you to buy the information.

A link to a similar but readable listing would also help.

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

Roger,
A good place for NMEA and GPS info is http://vancouver-webpages.com/peter/
krj

Autopilot NMEA question for gear heads
 

In article ,
"Roger Long" wrote:

Never mind. I found a list at:

http://aprs.gids.nl/nmea/#allgp

I'd still be interested in hearing about anyone's experience with such a
hook up.


You'll love it. We have a few paths plotted that take us just to the
edge of shallows we have discovered we can not cross.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's NEW Pages: http://web.mac.com/jerelull/iWeb/Xan/
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/

Autopilot NMEA question for gear heads
 

On Thu, 1 Feb 2007 18:48:55 -0500, "Roger Long"
wrote:

Never mind. I found a list at:

http://aprs.gids.nl/nmea/#allgp

I'd still be interested in hearing about anyone's experience with such a
hook up.

Most auto pilots want to know cross track error ($GPXTE), course over
ground ($GPVTG) and bearing to mark ($GPBWC).

I read throug the Garmin manual online and can't find any mention of
cross track error. I'd call Garmin tech support.

Autopilot NMEA question for gear heads
 

Wayne.B wrote:
On Thu, 1 Feb 2007 18:48:55 -0500, "Roger Long"
wrote:

Never mind. I found a list at:

http://aprs.gids.nl/nmea/#allgp

I'd still be interested in hearing about anyone's experience with such a
hook up.

Most auto pilots want to know cross track error ($GPXTE), course over
ground ($GPVTG) and bearing to mark ($GPBWC).

I read throug the Garmin manual online and can't find any mention of
cross track error. I'd call Garmin tech support.

GPRMB is what most autopilots use. It gives destination waypoint,
originating waypoint, VMG to waypoint and XTE
$GPRMB,A,0.66,L,003,004,4917.24,N,12309.57,W,001.3 ,052.5,000.5,V*0B

A Data status A = OK, V = warning
0.66,L Cross-track error, steer Left to correct
003 Origin waypoint ID
004 Destination waypoint ID
4917.24,N Destination waypoint latitude 49 deg. 17.24 min. N
12309.57,W Destination waypoint longitude 123 deg. 09.57 min. W
001.3 Range to destination, nautical miles
052.5 Bearing to destination
000.5 Velocity towards destination, knots
V Arrival alarm A = arrived, V = not arrived

Autopilot NMEA question for gear heads
 

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?

It also appears that, although it will roll over to the next waypoint, it
won't actually turn the boat until you push the keypad. That's good if
something is in the way; bad if you miss the waypoint alarm. Of course, as
the manual says over and over, you should be independently tracking your
position constantly. One of the thinkgs I look forward to in being able to
get my hands off the wheel is to start doing a lot more navigation.

All this makes me wonder. Can more sophisticated autopilots be made to
follow a series of legs without intervention? If so, it's only a matter of
time before someone figures out that a small ship filled with explosives
could be turned into an marine guided missile. The probability is about
zero since the terrorists like to blow up with their bombs and there are
much more effective ways to create mahem. I have to wonder though if the
people obsessed with taking away our 6 oz tubes of toothbpaste and hair gel
might be coming after our navigation electronics at some point.

--
Roger Long

Autopilot NMEA question for gear heads
 

It also appears that, although it will roll over to the next waypoint, it
won't actually turn the boat until you push the keypad. That's good if
something is in the way; bad if you miss the waypoint alarm. Of course,
as
the manual says over and over, you should be independently tracking your
position constantly. One of the thinkgs I look forward to in being able
to
get my hands off the wheel is to start doing a lot more navigation.

Getting your hands off the wheel doesn't mean no interaction with it.

Autopilot NMEA question for gear heads
 

Roger Long wrote:
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?

It also appears that, although it will roll over to the next waypoint, it
won't actually turn the boat until you push the keypad. That's good if
something is in the way; bad if you miss the waypoint alarm. Of course, as
the manual says over and over, you should be independently tracking your
position constantly. One of the thinkgs I look forward to in being able to
get my hands off the wheel is to start doing a lot more navigation.

All this makes me wonder. Can more sophisticated autopilots be made to
follow a series of legs without intervention? If so, it's only a matter of
time before someone figures out that a small ship filled with explosives
could be turned into an marine guided missile. The probability is about
zero since the terrorists like to blow up with their bombs and there are
much more effective ways to create mahem. I have to wonder though if the
people obsessed with taking away our 6 oz tubes of toothbpaste and hair gel
might be coming after our navigation electronics at some point.

--
Roger Long


If for some reason you get off your track, the autopilot will make a
converging track to the destination waypoint. I don't know about the
ST1000 but my ST4000+ has an option that can be selected to turn to the
next waypoint or wait for input before turning. I selected wait for me
to decide. There may be some reason I don't want to turn.
krj

Autopilot NMEA question for gear heads
 

On Feb 1, 6:29 pm, "Roger Long" wrote:
I just bought a Raymarine ST1000 Plus tiller autopilot for my Endeavour 32.
The astute among your will immediately wonder how this will work on a 13,000
pound 32 foot wheel driven boat. The unit will just drive the vane servo
shaft on the Cape Horn steering gear now on order. We could have bought even
a smaller tiller pilot if one was available.

Since I was trying to buy the smallest and cheapest unit I could get, I was
surprised to find out how sophisticated it is. Given the right NMEA input,
it evidently will follow a track to a waypoint instead of just blindly
maintaining a given course. It will even rollover to a new waypoint and run
another leg.

The Raymarine manual describes the inputs needed to follow a track but in
plain English. The Garmin manual for the GPSmap 76Cx I will be using says:

The following are the sentences for NMEA 0183, Version 3.01 output:

Approved sentences-

GPGCA

GPGLL

GPGSA

GPGSV

GPRMB

GPRMC

GPRTE

GPVTG

GPWPL

GPBOD

GPAPB

If anyone could annotate a quoted copy of this list I would appreciate it. I've
tried to find a listing via Google but the only one I can turn up is quickly
replaced by another page before I can read it. Presumably, the Capt'n wants
you to buy the information.

A link to a similar but readable listing would also help.

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

--
Roger Long

Roger,

The ST1000 manual (http://www.raymarine.com/raymarine/Default.asp?
site=1&SECTion=3&Page=337&Parent=166) on page 47 lists the NMEA inputs
accepted. And what sentences contain each item.

Most likely if you just wire up the Garmin and the ST1000, it will
work. The garmin most likely is set to transmit the most usefull NMEA
sentences allready. Sentence APB (Autopilot B) seems most
appropriate.

Check crossing of NMEA + and - if it doesn't work.

Todd Smith