Raymarine ST1000 - locking onto waypoints

[Burnham Bob]

my plotter outputs bearing and cross track error, so the Raymarine manual says the autopilot will steer from one waypoint to another. from the comfort of my armchair, before i try it in real life, i'd like some advice. the autopilot manual says it can't recognise waypoint names of more than four characters. does this mean simply that the advance function won't work when a waypoint is reached and the plotter switches to the next one, or more seriously, that the autopilot won't 'lock on' to any waypoint with a name longer than four characters?

i don't intend to use the function much - preferring to shape a course to steer the old fashioned way and put that into the autopilot - but i can't work out the answer from the Raymarine manual

anyone out there know the answer?

 

[chewi]

I can't say I know the answer, but I tried this with my 2000+ connected to a Garmin 152 (Because it was there!)
The snag is it doesn't steer itself at one waypoint to the next (because there might be traffic to hit, and its the helmsmans job not to!), so it just beeps and you are expected to confirm the course change, so there's not a lot of point in it really, however many characters it supports.

I find it better just to use the GPS to show bearing/course to your next waypoint and get the Autohelm to achieve it by +/- a degree or so, then repeat when navigating to the next waypoint. That way the nmea is not needed ( or depended on) and its operation is that much more apparent.

 

[Burnham Bob]

thanks.......i do know that i would have to say yes to a change of waypoint, what i really want is to just let the autohelm steer to the next waypoint. unless i tell it a course to steer, it will drift off the required track if i simply put in a heading, as leeway and tidal drift take over.

i just hope that it will lock on to a waypoint with more than four letters in its name!

 

[misterg]

i just hope that it will lock on to a waypoint with more than four letters in its name!

I'm pretty sure the tiller pilot doesn't "lock on" to a waypoint as such. (We used to have a ST2000+ which operates similarly.)

The GPS / Plotter does the navigating between waypoints and the tiller pilot picks up the 'bearing to waypoint' and cross track error from the NMEA data output by the GPS. It will happily track this course with or without a waypoint name AFAIK. If the tiller pilot "notices" the waypoint name in the NMEA data changing, then it freezes it's current heading and sounds the waypoint advance alarm. It won't turn onto a new heading until the alarm is acknowledged. The instructions imply that it won't notice a change in waypoint name if it is longer than 4 letters. My recollection is that longer names didn't seem to bother our ST2000+, but maybe the first 4 letters were unique, I can't remember!.

Andy

 

[simonfraser]

When using the same my ST does some alarming course 'corrections' when initially locked onto a way point. This does settle with time, but is useless for sailing.
Setting the course direction using the auto function works just fine, i dont bother locking onto a way point.

 

[wooslehunter]

Autopilots do not lock on to way-points. They have no idea about them other than what they are told by the GPS. A GPS may send out data through the NMEA interface in an APB sentence as below:

$GPAPB,A,A,0.10,R,N,V,V,011,M,DEST,011,M,011,M*3C

where:
APB Autopilot format B
A Loran-C blink/SNR warning, general warning
A Loran-C cycle warning
0.10 cross-track error distance
R steer Right to correct (or L for Left)
N cross-track error units - nautical miles (K for kilometers)
V arrival alarm - circle
V arrival alarm - perpendicular
011,M magnetic bearing, origin to destination
DEST destination waypoint ID
011,M magnetic bearing, present position to destination
011,M magnetic heading to steer (bearings could True as 033,T)

So, the auto-pilot only knows the info above. The auto-pilot then works out what to do to get to the waypoint using the info given.

The ST1000 will not change course once it reaches a waypoint automatically. It will set off an alarm & you need to confirm the course change. There may be a boat in the way for instance & an immediate course change would cause a collision.

 

[zoom350]

Confirmation

Autopilots do not lock on to way-points. They have no idea about them other than what they are told by the GPS. A GPS may send out data through the NMEA interface in an APB sentence as below:

$GPAPB,A,A,0.10,R,N,V,V,011,M,DEST,011,M,011,M*3C

where:
APB Autopilot format B
A Loran-C blink/SNR warning, general warning
A Loran-C cycle warning
0.10 cross-track error distance
R steer Right to correct (or L for Left)
N cross-track error units - nautical miles (K for kilometers)
V arrival alarm - circle
V arrival alarm - perpendicular
011,M magnetic bearing, origin to destination
DEST destination waypoint ID
011,M magnetic bearing, present position to destination
011,M magnetic heading to steer (bearings could True as 033,T)

So, the auto-pilot only knows the info above. The auto-pilot then works out what to do to get to the waypoint using the info given.

The ST1000 will not change course once it reaches a waypoint automatically. It will set off an alarm & you need to confirm the course change. There may be a boat in the way for instance & an immediate course change would cause a collision.

There is a way to bypass the confirmation alarm and go directly to the next waypoint ?

 

[chewi]

Not that I am aware of, as wooslehunter said, it could cause a collision into a nearby boat, or even into the waypoint itself.

 

[colvic987]

Not that I am aware of, as wooslehunter said, it could cause a collision into a nearby boat, or even into the waypoint itself.

I normally program the waypoint as an area of unrestricted seaway, within a safe distance of the buoy or structure if that's what I am navigating past or too, so I will never hit anything at the waypoint. Its just a navigating mark to aim for. mark one eyeball is also switched on at the time... as well as some grey matter

 

[chewi]

True, but the software cannot know that.
It cannot safely turn the boat without the local eyeball confirming it it safe to do so.

 

[colvic987]

True, but the software cannot know that.
It cannot safely turn the boat without the local eyeball confirming it it safe to do so.

And that's why any navigation program or autopilot cannot be safely left doing its programmed route without someone in the cockpit with the ability to take command if the situation demands.

 

[macd]

the autopilot manual says it can't recognise waypoint names of more than four characters. does this mean simply that the advance function won't work when a waypoint is reached and the plotter switches to the next one, or more seriously?

Certainly for going to one waypoint, the tillerpilot doesn't care what that waypoint's called: to the instrument it's just 'the waypoint". It'll go there (or rather, be instructed by the plotter how to get there...it's just a slave). I'm pretty sure the same is true for routes, which is what multiple waypoints are usually called, with the confirmation at each course change.

simonfraser: the erratic initial course-keeping suggests that the instrument's compass may be mis-calibrated.