I've got a Lowrance compact color unit. It has two cabling connectors in back: One for the transducer, one for ....?? I don't recognize the connector type. Is it NMEA? The manual says nothing.

It's for interfacing mutiple units. Stands for: National Marine Electronics Assn.

Paul, if you have only two connectors on the back or your unit, one is for the transducer and the other is for 12V power.  If there are three, then the third is for the NMEA3000 network.  Go to www.lowrance.com for more information.  Lowrance has great tutorials on their site.

Thanks guys.

It has two. The first is the transducer and power together. The second is the one in question; it has 4 pins and a bar separating the two.

I have been to the Lowrance site and found nothing helpful pertaining to my particular unit. Will poke around the site some more.

That plug, I do believe is an accessory plug for something such as a speed sensor or additional temp sensor. Contact Lowrance to be certain: they are very helpful.

Thanks George.