[DG] [DG11] ST6001 in the arctic

[Gedmclean]

I am planning to sail through the arctic next year. I have heard that the ST6001 using a flux gate compass is not reliable at high latitudes due primarily to the general problems with compasses up there, so really it’s the full gate compass which will be he problem.

I am therefore looking for information on operation of the system at high latitudes, in particular wanting to know if there is an alternative to the flux gate (gps heading sensor?) that I can install to provide simple autopilot (go straight) control.

Thanks.

[Derek - Raymarine - Moderator]

Hi Gedmclean

Thankyou for your enquiry.

The issue at higher latitudes is due to the angle of dip of the magnetic field as you get nearer the poles - typically above 60 degrees which causes the conventional compasses, wet card and fluxgate , to become oversensitive to turn and give the effect of oversteering.

Gyrocompasses and some GPS compasses offer much better performance and are favoured by polar sailors, but also the current generation of Evolution autopilots - using the EV1 solid state sensor for heading information perform very well in these more extreme latitudes.

We have reports of GPS compasses being connected to the SPX autopilot computers and to current Evolution autopilots and operating satisfactorily in these latitudes, although we have not tested them ourselves and so cannot recommend a specific model or make.

Regards

Derek

[Gedmclean]

Thanks for the explanation of the compass problem.

My understanding is that if we remove the flux gate compass (4 wire analog) the autopilot will look for an appropriate heading sentence in nmea and use that for control.

My thought to test the system before buying a solid state heading sensor is to use a regular gps that will output the required nmea heading sentence, then temporarily remove the fluxgate and see how the system works. If it works then we’ll go the next step to sourcing a new sensor.

Does that sound like a reasonable plan?

Thanks,

[Louise - Raymarine - Moderator]

Dear gedmclean,

Thank you for your post.

This option will work fine, do keep hold of the fluxgate compass as a spare for lower latitudes.

Many Thanks
Louise