[TG11] ST40 Depth flashing "Last" in 15 ft of water

[Breakin Away]

Hi all,

I am having some problems with my ST60 depth transducer, and maybe with some other ST60 Seatalk devices.

My depth transducer will report the accurate depth for about 10 seconds, then will flash "Last" for about 10 seconds, then report depth again. This was in my slip with boat sitting still. When sailing, we had some more severe behavior, such as the "Last" value suddenly jumping to 3.5 feet (in an area that we knew to be 15 feet), and all the alarms going off. This seems to be a random occurrence, but can last 10 or 15 minutes, with the alarm repeatedly coming back a minute after I silence it. It's not totally random, since it seems to especially occur when we abruptly change direction, as when we tack.

There are other "gremlins" in our system that might or might not be related to this. I have the ST100 wireless autopilot remote. It's worked perfectly for 4 years on two different boats, but this year its reception has suddenly dropped to about 3 feet. It used to work over 30' away from the transmitter. New AAA batteries in the handheld device did not solve the problem.

Also, my ST60 wind transducer suddenly was 30 degrees out of alignment. I tried to fix this through calibration, but after turning the boat through circles the acknowledge beeps never happened. I had to give up after 3 full circles due to too much boat traffic in the area.

All of these problems cropped up suddenly after launching after being on the hard over the winter. In past years we never had any problem like this - everything was rock-solid. We've made no hardware changes to our setup. Since the manual suggests that the flashing "Last" message indicates a poor connection, I opened up the Navpod today and inspected and re-seated all the Seatalk connectors as well as the 3 depth transducer wires. No signs of any corrosion or other problems.

I'd appreciate any suggestions, especially if there is a way to diagnose whether the depth problem is control head or transducer. Obviously I hope it's not the latter, as that may require a haul-out.