SeaTalk to NMEA format

wizard

wizard

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Would be very grateful to know if there is a way to convert seatalk to nmea apart from the very expensive Raymarine box at £100+ ?

I just need to send heading info from an ST40 compass to my Simrad combi instrument.

Thanks in advance if there is a way.
 
I know about the incompatibility but what I am after is - does somebody have a circuit diagram that will do this ?
 
It's more than a simple circuit that's required. Not only are the voltage levels different (for which a simple circuit will do) but the data format and protocol are completely different. A processor is required.

This website shows a amateur processor-based ciruit board that will do the job, but it costs a bit...

NMEA/Seatalk converter

The Seatalk protocol and format is not in the public domain, but has been cracked and published here...

Thomas Knauf's Seatalk page

I have 2 of the converter boxes, and they work faultlessly (partly because I was an early tester and identified all the bugs /forums/images/graemlins/smile.gif)
 
The seatalk to NMEA boxes often come up on eBay for about £50. Some ST instruments have a NMEA output built in. The ST50 repeater does and you can often pick these up on eBay.
On my original ST50 compass, Raymarine offered an male/female adapter cable that went in line with (I think) the sensor cable and had a two wire NMEA out. That if available for your compass would be a much lower cost route. I may still have it somewhere.
 
I have just been looking at those sites as your message reply came up- as you say the circuit is complicated because of the unusual way that seatalk operates.

The other problem is the circuits are not much cheaper than the Raymarine original and when I find that to be the case I always go with the manufacturer despite the cost /forums/images/graemlins/frown.gif

Still, it must have been an interesting challenge for you in itself just to break the code and design something -well done
 
The reason for this is that I have acquired a Raymarine fluxgate transducer as I want to have heading information on a separate display system on the boat apart from the main Raymarine system in case of failure of one system.

I will check the raymarine website to see which compass display unit if any actually puts out nmea data.

I will also put a search in on eBay as well thanks for the tip
 
Just to clarify, I wasn't involved in the cracking of Seatalk or the design of the converter. I was just a lowly tester.

The Raymarine converter has come down in price a lot since the amateur board was first produced. As you say, it's not much cheaper than the manufacturer's box now, but it used to be.
 
Re: Look at US price...

With the dollar so low it is worth a chance - but I have tried in the past to order from US chandlers.

Its fine on the smaller company items but when it comes to the big names like Raymarine they suddenly run out of stock or some other excuse!!
 
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