Raymarine ST40 Depth

dlochner · Dec 7, 2019

If the transducer has failed, then the first question should be can you find a new compatible transducer? Airmar makes most of the transducers. Are you certain it is the transducer and not the instrument head?

You may end up biting the bullet and purchasing a new depth sounder which will probably not use the same cable. Contemporary DS use NMEA 2000 and not proprietary protocols like the ST40.

Hello Below · Dec 8, 2019

Ken13559 said:
Hi, if my Raymarine ST40 Depth transducer is faulty, can I cut old wire and splice new on to it? It's a pain to run new cables thru crooks&canny.
Will it work or is Depth transducer are so calibrated that extra cable length can be a problem?

Ken Y

Ken, if your transducer is faulty and if you can get a compatible replacement and if you cannot or do not want to run the new cable read this:

Airmar Inline Cable Splice - Old SBO Post

dlochner · Dec 8, 2019

Hello Below said:
Ken, if your transducer is faulty and if you can get a compatible replacement and if you cannot or do not want to run the new cable read this:

Airmar Inline Cable Splice - Old SBO Post

Wish I had seen the cable splice when I ran an cable for a remote VHF mic. Much easier than soldering and heat shrinking a mess of tiny wires.

This may not work on the old style cables. Many of them were shielded single conductor cables.

Hello Below · Dec 8, 2019

Ken13559 said:
I have in mind to use water tight heat shrinkable solder joint. Now this IP67 rated connector is another option. Thank you.
But question remains, is it ok to splice and join transducer cable?
I did that for paddle-wheel speed and it works ok but is unsure of depth sensor.

Ken Y

I used the connector for a dst800 analog transducer over 2 years ago and all 3 devices (depth, speed, temperature) have worked like they are supposed to. Have a read of this link: Try this link

AlanRothenbush · Dec 10, 2019

Ken13559 said:
Hi, if my Raymarine ST40 Depth transducer is faulty, can I cut old wire and splice new on to it? It's a pain to run new cables thru crooks&canny.
Will it work or is Depth transducer are so calibrated that extra cable length can be a problem?

Ken Y

All the electronics on my old boat were removed pre-purchase somewhat crudely, with cables simply being cut here and there, including the cable to the Airmar (I think) 3 in 1 transducer.

I took a chance and bought an ST 40 head and used about 20 feet of nothing special multi-conductor cable to connect to about 20 feet of cable coming from the transducer. The interconnect was just a terminal strip in a plastic box.

It works fine, with depths being pretty darn close to what I measure with a lead line.

The paddle wheel also works .. for about a day, after a bottom cleaning.

The water temperature is off by miles, but I don't really care. In my part of the world, the water is only ever one of two temperatures .. cold or really cold .. the distinction being pretty subtle.

Your mileage may vary, of course but I'd say it's worth a try!

Alan