Thanks Ziggy. Right from the beginning the depth has been inconsistent, (randomly reads 3.9 ft regardless of depth. Now the temperature has stopped working altogether.
If as you say it's reading 3'9" the problem is very likely "keel bounce" as I wrote before.
It "sounds" as though it is roughly measuring your keel depth which will be approximately your draft
minus the depth of your transducer in your hull.
When I had keel a bounce problem with a new keel, my reading was 1 metre or 39" and similar to what you are experiencing.
If you consider that likely you might be able to get another transducer and install it in a better location, maybe fwd of the keel ( I can't see your boat). You can do that without hauling out as has been explained. Leave the old transducer in place until your next haul out.
If you have keel bounce a new system will also have the same problem.
Your temperature ( and possibly the sounder) can also be affected by EMI; electromagnetic interference
from various possibilities. In my boat my Wind
direction and Temp were affected by EMI from the alternator
to smart regulator
cable until I shielded the entire length of the cable with tinned copper braid earthed to the engine
I have 2 sounders with transducers both ahead and behind the keel. One reads inside the cabin
. The other in the cockpit
. The fwd one needed its transducer relocated even further ahead which fixed the bounce problem.