But you have done it. As already said, transducer cables are usually a fixed length - don't mess with them. The capacitance of the cable matters. Now that you have cut it splice the new cable back together and use heatshrink with glue to seal it. Maybe use two layers of heat shrink.

I have a ton of cables in the bilge but not a single splice. I went as far as using unspliced masthead antenna and wind instrument cables all the way to the radio and instrument. A little more work when stepping/unstepping but I only do that about once a decade.