Help Required re auto pilot purchase

[powbongo]

Does anyone on the forum have experience of connecting a standard Horizon CP300 chart plotter up to an autopilot. I am thinking of replacing a autohelm 4000 that drives a wheel with an auto pilot that could talk to the CP300 chart plotter. Any advice re costs, suitable makes etc would be appreciated.

 

[V1701]

It's a case of checking that the NMEA output of the autopilot is compatible with the CP. I've connected my Simrad TP22 to a SH CP180, not tried it out yet though...

 

[wooslehunter]

No problem with ST2000+ & CP180. Just connected the NMEA. Can't remember if I had to change any menu settings but install was easy. Works fine too. Having said that, I rarely use the track function. Most useage is to hold a compass course which the auto-pilot does on its own. I sometimes lock to wind just off close hauled which is fine as long as it's not too gusty or swinging too fast.

 

[maby]

As I discovered recently, Raymarine will not make any commitments about compatibility of their autopilots with any other manufacturer's plotters. When I contacted them about lack of compatibility between an SPX-5 and a Lowrance plotter they replied that they were not surprised. Lowrance told me that they had received reports of incompatibility but Raymarine do not publish their interface requirements, so they (Lowrance) cannot program their devices to meet them.

I doubt that you will get any manufacturer to commit to compatibility with anyone else's products - you will be dependent on reports from other users on forums like this one.

 

[aluijten]

On my previous boat I hooked up a CP300 and a ST4000 (not the + version) and that worked very well. On the CP300 you can choose the output (sentences) to be sent over the various NMEA ports if I remember correctly. Very nice piece of kit and I ended up hooking it up several diffent instruments in the end.
I don't think you will have other costs then the purchase of a new autopilot assuming you'll do the installation yourself. The connection between the AP and the CP300 does require some study to determine the correct wiring.

 

[Baggywrinkle]

The yellow wire from ACC1 on the CP300 goes to NMEA +ve on the Autopilot Head, The green wire on the plotter (NMEA Common) goes to the NMEA -ve on the Autopilot head.

This works for my SH CP300 to Raymarine Autohelm 4000+ and the Autopilot will accept waypoints from the plotter. It's just the costs of the wiring.

My advice would be to simply hook it up and try it. If it works, like mine did, then you save the cost of replacing the autopilot.

Here's my wiring diagram ...

 

[Tranona]

The installation instructions for the Raymarine course computer clearly show how to connect for NMEA to interface with Seatalk

 

[powbongo]

Many Thanks

To all who replied, thank you very much for your superb information

 

[maby]

The installation instructions for the Raymarine course computer clearly show how to connect for NMEA to interface with Seatalk

Unfortunately, it's not just the electrical connection that is important - it's the information that the plotter pushes to the AP. My SPX-5 is perfectly aware of the plotter and will make use of information such as wind speed and direction that are gatewayed through it to steer to wind. The AP control head is aware of the data coming from all the sensors on the boat and can display speed, depth, wind etc. The trouble comes when I try to put it into Track mode to follow a course from the plotter - then the SPX-5 complains that it does not have enough navigation data - despite the fact that it starts to display distance and bearing to waypoint. Raymarine tell me that it requires information about things like the magnetic variation and datum in force in order to ba able to do its calculations, and this error message usually indicates that the plotter is not outputting one or both of these in a format that the SPX-5 can understand.

 

[Tranona]

Does not surprise me. I could never get my previous ST 4000 to read from a Navman plotter, even though it was just a cable from the plotter to the control head.

Not even bothered with the SPX5 I have now. Not the best bit of kit as I am now on my third drive and a software update, fortunately all done undr warranty but still frustrating!

 

[aluijten]

Unfortunately, it's not just the electrical connection that is important - it's the information that the plotter pushes to the AP. My SPX-5 is perfectly aware of the plotter and will make use of information such as wind speed and direction that are gatewayed through it to steer to wind. The AP control head is aware of the data coming from all the sensors on the boat and can display speed, depth, wind etc. The trouble comes when I try to put it into Track mode to follow a course from the plotter - then the SPX-5 complains that it does not have enough navigation data - despite the fact that it starts to display distance and bearing to waypoint. Raymarine tell me that it requires information about things like the magnetic variation and datum in force in order to ba able to do its calculations, and this error message usually indicates that the plotter is not outputting one or both of these in a format that the SPX-5 can understand.

From what you write I think the most important piece of information is missing for the Autopilot. To be able to steer to a waypoint it needs the XTE information (Cross-Track Error).
What I remember from my old ST4000 is that this is basically the only thing it needs to steer to a waypoint, all the rest is nice to have. It may be that "Distance to Waypoint" is also a prerequisite, I can't remember.

Cheers,

Arno

 

[aluijten]

To all who replied, thank you very much for your superb information

Just as a information:

If you now own a Autohelm 4000 and not the Autohelm ST4000 (the difference being ST) then you have no way of interfacing to the plotter as the old model has no NMEA interface.

Cheers,

Arno

 

[maby]

From what you write I think the most important piece of information is missing for the Autopilot. To be able to steer to a waypoint it needs the XTE information (Cross-Track Error).
What I remember from my old ST4000 is that this is basically the only thing it needs to steer to a waypoint, all the rest is nice to have. It may be that "Distance to Waypoint" is also a prerequisite, I can't remember.

Cheers,

Arno

I don't think so. It certainly has the XTE since the autopilot controller displays it. The way the Raymarine support described the problem, it sounds like the SPX-5 course computer tries to do all the calculations itself - receiving both the boat's current position and that of the next waypoint as latitude/longitude plus the magnetic variation and datum in force for those coordinates, then calculating the course to steer from first principles. I don't know why it does this if the plotter has already done it and is simply outputting the XTE. Anyway, the Raymarine man thought that the most likely explaination was that the plotter was not outputting at least one of those parameters.

 

[aluijten]

I don't think so. It certainly has the XTE since the autopilot controller displays it. The way the Raymarine support described the problem, it sounds like the SPX-5 course computer tries to do all the calculations itself - receiving both the boat's current position and that of the next waypoint as latitude/longitude plus the magnetic variation and datum in force for those coordinates, then calculating the course to steer from first principles. I don't know why it does this if the plotter has already done it and is simply outputting the XTE. Anyway, the Raymarine man thought that the most likely explaination was that the plotter was not outputting at least one of those parameters.

Go Raymarine! Great way to improve functionality

 

[RupertW]

Go Raymarine! Great way to improve functionality

Well, the best commercial strategy for a new entrant to the marketplace is complete interoperability and upgrades as the competitors change.

For an existing manufacturer with a decent share of the market the best approach is to squash other competitors by just playing lip service to compatibility so that people buy all the components from you.

Not nice but understandable in a tight market.

 

[Tranona]

Well, the best commercial strategy for a new entrant to the marketplace is complete interoperability and upgrades as the competitors change.

For an existing manufacturer with a decent share of the market the best approach is to squash other competitors by just playing lip service to compatibility so that people buy all the components from you.

Not nice but understandable in a tight market.

However, you run the risk that customers will get peeed off and if a credible competitor comes along he has a ready market. Note that Bavaria now fit Garmin equipment, having been loyal Raymarine for many years.

 

[maby]

However, you run the risk that customers will get peeed off and if a credible competitor comes along he has a ready market. Note that Bavaria now fit Garmin equipment, having been loyal Raymarine for many years.

I think it's more a question of the fundamental flaws in NMEA (both 0183 and 2000) - it started out as a simple mechanism for transferring some basic data items around and has evolved almost organically since then. Nobody has actually sat down ad defined the structure of the conversation for a plotter driving an autopilot and there are multiple ways to express the functionality - different manufacturers have different ideas of what should be exchanged and in which sequence.