Advice, please re misbehaving ST60 depth/speed?

[Gosportsailor]

Good Morning All
Is there anyone out there who can help? My ST60 depth/speed instrument is freezing after a couple of hours use on a very high reading for depth (yesterday 50') It also seems to be under-reading for speed through the water. Log spins freely, and is kept out of water when not in use. The other instruments linked in (wind/compass) seem to be working fine.
Any ideas as to what might be the cause?
Thankyou

 

[Bobc]

Check the connectors on the back of the head unit. Might just be corroded spade terminals.

 

[MattK1969]

Sounds like two separate issues maybe. You can recalibrate the speed if you read the manual, it's quite faffy. Mine is old and despite many recalibrations, installing a service kit and painting it with transducer paint, it persistently undereads speed by about 20%, I just live with it.

 

[Aja]

My ST60 depth will lose readings at about 100+ metres. Sometimes will go up to 120 metres and at other times only goes to 85+ metres. I suppose it depends on the actual depth, speed of the vessel and the type of sea bed (mud, rock, uneven surface etc). If yours 'freezes' at 50 feet you may want to re check the parameters from the manual.

For the Speed, check your against a GPS at slack water, if you can. You can go into calibration mode (CAL) and adjust.

 

[earlybird]

Your depth transducer might be transmitting a weakened signal; eg covered in anti-fouling paint or, if internal, poor coupling througth the hull.
If / when you recalibrate the speed, there will most probably be no perfect correction factor. Mine tended to under-read at low speeds and over-read at high speed. Best to try to compromise at a typical sailing speed.