The trolling motor cut the transducer wire when we put it down. Can you splice a transducer wire?

It can be done but weather it would read correctly is something you would have to try and see. I have spliced coaxial cable before but never a TM cable so not sure but it cold be possible. If the splice is under water you would really have to water proof it with some spray on rubber insulation then put 130C rubber tape over that with 130 plus tape over that. You have to make sure you keep the ground sheild and the main wire seprate/isolated that could be a chore. If it were me i would just bite the bullet and buy another transducer or see if anyone on here has a used one they want to sell. If you get a new/used one you could always try the splice and see it would work then you would have a spare. I'm sure some there is someone on here will chime in if they have ever done it it's a cable so it can be spliced but the problem is with electronics is that you'll sometimes have a lot of interferances/noise afterwards.

I have spliced cable before and didn't have good results. It worked fine until the I put it in the water. Like CB said, you really have to waterproof it and that's hard to do with cable that small. Also had a small nick in a cable (from TM also). I tried waterproofing and taping but no go. Get a new transducer and be careful how you run the cable down the TM. They're pretty sensitive but it takes a pretty good pinch to ruin it. I've bumped into stumps and the ducer kept working.

Works for me but only if its a shielded mesh wire and not the foil type. You could always use a set of coax connectors and put a male and female on.

You can weather proof either fixes by using some liquid electrical tape (spray can) and cover that with a piece of heat shrink tubing.

Yes, it can be done. Just make sure you repair the shield properly after repairing open wire. Then use a good seal with heat shrink, I've done it many times.

You can try...if it doesn't work them you know what to replace. Make sure the connections are water tight and you keep the shielding or more issues could happen.

This question has been asked many, many times before and the fish finder fix-er uppers will tell you since they did it and they or their customers don't see themselves much of a difference, it can be easily done with just a soldering gun, some heat shrink and sealant.

The truth though is that without carefully using some expensive electronics test equipment, it's a compromised repair at best and afterwords for HDS & other better quality sonar units, it will not be hard to tell that the splice is compromising the digital filtering circuits. It is impossible to know if a good splice is good by just looking at it.

Anyone having much experience making matched splices with assistance of a TDR scope will understand what is involved in splicing signal cables..... but you can always try it and see if it works 'good enough' for you if you don't want to pay for a new transducer. And waterproof 'Coaxial connectors'(not the TV cable company kind) would be a possible solution if they were selected/terminated to be of the specific cable's characteristic impedance.

I have used this several times with good results
http://www.plastidip.com/home_solutions/Liquid_Tape_-_Electrical_Insulation

I really appreciate all your inputs. Partner says its a single wire but he has been known to miss things right in front of his nose. It may take a while for me to get at it. I can easily understand that this is a complicated piece of electronic gear and all I can do is follow the advice and it will work or not work. Then it's back to the store I guess. Fortunately it is an old unit that is " simple " compared to many I see today.

Yep, your partner missed a wire/s. There are at least two not counting the temp sensor circuit.