If the cable were damaged farther away from the transducer, it would be possible to repair it (with great care).
With the cable damaged right at the transducer, I don't think I would try to repair it, and I am pretty handy with electronic stuff. I also would not connect it to the unit in it's present condition......you could let the smoke out of your unit.....only Humminbird would be able to put it back in.