What the heck is this for?

[senormechanico]

What is the purpose of this black box I found and why was it installed? The insides are obviously Raymarine brand even though there are no names or other identifying things on the outside.

I ran across it while cleaning up a poor wiring installation done by the previous owner of my boat. All my instruments are Raymarine with the exception of the GPS/chartplotter which I'm replacing with a Garmin 5208.
(Whooeee is it a nice unit!)

This mysterious box was hooked up such that it constantly drew battery power, but as far as I can tell it wasn't doing anything. There are 3 wire bundles coming out of it. One is a 3 terminal Seatalk wire, and the other two have been cut off about 6 inches out of the box and redone with after market wire. One of those is hand labeled DATA and another is hand labeled POWER.

I traced the Power lead which had been connected to the house battery, and the Data leads went to the autopilot and also to the GPS NMEA terminals.

The inside of the box contains a Raymarine circuit board with several computer microprocessor chips, a crystal labeled 12.0 for the processor clock, a 5 volt regulator and a few other integrated circuits as well.
One of the microprocessors has a V 05 label on it and a sticker on another chip says
NAUTECH
A090694

Another chip is labeled
NAVDATA
09731

The circuit board itself has a number etched on it.
3015-053 A NAVDATA

I suspect it is either a Seatalk to NMEA 0183 converter or NMEA 0183 to Seatalk, but I'm not sure. All my Raymarine instruments work normally without this box.

As I am in the process of installing a chartplotter which needs NMEA 1083 or NMEA 2000, it would be great if I could read the Seatalk information on the plotter.

Thanks for your help!

Steve B.

[Joli]

That would be known as wiring abandoned in place. You'll find lots of that on older boats sometimes.

[scotte]

The description of where the leads where going and the connectors you can see are consistent with your analysis - that it's an NMEA/SeaTalk converter box. Note we don't know if it's NMEA->SeaTalk or SeaTalk->NMEA or bidirectional...

It most likely is functional and useful - with the instruments in the right mode it could be repeating data between them...

[AnchorageGuy]

Steve, More than likely if it has a Raymarine identification inside somewhere it is a converter and is designed to let your Sea Talk instruments communicate with a non Raymarine MNEA input.

[senormechanico]

Thanks guys.

Chuck,

That was what I hoped for, but the picture you see is all there is.

The box it's housed in is professionally built and looks to be original. There are absolutely no labels inside or out and there is no evidence of any labels having ever been attached other than what you see in the pictures.

The box was double sticky taped in place with one big black sheet. I've never seen any hardware/marine store tape like it.

I posted basically the same request to Raymarine. We shall see if they come clean with an answer, but the last time I requested information about NMEA/SeaTalk connectivity, I got a runaround answer saying it was proprietary, blah blah blah...

What ever I hear, I'll post.


Steve B.

[AnchorageGuy]

The Nautech sticker in the box, Nautech used to be the maker of Autohelm if I am not mistaken.

[AnchorageGuy]

see if this helps
http://www.raymarine.com/submittedfi...81166_3www.pdf

[senormechanico]

Originally Posted by Chuck Baier

see if this helps
http://www.raymarine.com/submittedfi...81166_3www.pdf

That sure looks like it! Thanks!
It will be interesting to see what Raymarine says.
I'll do some further homework after reading the pdf.

Steve B.

[senormechanico]

Here's the response I got from Raymarine this morning via email:

"I can not tell you. We had a NavData instrument that repeated GPS data, but it had a LCD display. Someone may have used this box to get GPS data over to your autopilot of GPS system. It is not a "Raymarine" install so I am not sure."

Chuck,
After looking at the pdf you found, I have concluded it's not the same thing. Two of the wire bundles from the outside go to the same exact places on the circuit board. Those are apparently the SeaTalk connections and pass thru. That leaves only 2 other wires which are probably NMEA 0183 output. (the conclusion arrived at by the Raymarine tech). I'll just hook it up to my new chartplotter when I get around to installing it and see if it passes depth and heading from my SeaTalk stuff.
Thanks for your sleuthing.

Steve B.

[scotte]

From a look at the close-up of the PCB, I can see that the two outer cables are clearly both SeaTalk. This is a pretty normal arrangement, so that SeaTalk devices can be looped together easily - and the board also gets it's power via these connections.

The middle cable is probably NMEA out or NMEA in, but not bi-directional (as there are only two wires). A closer look at the PCB may have some silkscreen with labelling if you are lucky.

Nautech was the manufacturer of equipment sold under the Autohelm brand. From the history I can find, Raytheon bought Nautech in 1990, and Raymarine bought the marine division of Raytheon in 2001.

[senormechanico]

Scotte,

You're right about the Sea Talk wiring.

I'm now pretty sure the other two wires in the middle are NMEA out as the only non Sea Talk item on the boat is the old chartplotter I'm replacing.

I don't think this thing was ever hooked up correctly as the only Sea Talk plug on it wasn't connected to anything. The other Sea Talk wire (the one on the right) was wired so it got house power 24/7! The middle two wires went to the Autohelm 4000 pilot which is ALSO connected by the normal Sea Talk string! Go figger!

I'm going to further study the old Autohelm radar manual this afternoon as it covers a bunch of stuff about NMEA, the heading sensor etc. If I can use this mystery box as a seatalk to NMEA output, I'll have it made.

I don't need NMEA to Seatalk (I think).

BTW, all the stuff on the boat is actually labeled Autohelm (original equipment vintage 1995), but of course has Raytheon equivalents.

Steve B.

[senormechanico]

OK guys, I figured this thing out. The Sea Talk leads are in/out pass thru and the middle wires (red and blue) are NMEA out.

The Autopilot was ignoring the nmea because it already had Sea Talk, so the box wasn't doing anything but continually eating juice and heating the boat.

I'm going to use this to feed the converted Sea Talk information to my new Garmin 5208, and hopefully I'll be all done installing everything by this afternoon.

Thanks again for everyone's ideas.

Steve B.

[AnchorageGuy]

Pretty much what I figured. Should work fine with the Garmin.

[swagman]

If anyone doubts the huge value of this site they need to be shown this complete thread.
A perfect example of sailors helping sailors when clearly professional could (or would) not.
Brilliant - and well done everyone involved.
JOHN