Marine: Boating, Sailing, PWC, GPS and Navigation - Rewiring tilt limit switch

I just installed a "coastkey" instead of the key-ignition/starter and it works really well. It is a wireless killswitch with ako remote that kills the motor if the pilot falls off the boat, but without the cord... This remote also works for ignition, starting the engine(s) and for in and out movement of the stern drive.
I discovered that the cables to the limit-switch on the side the transom assembly are very old and worn out by age. They go from the inside of the boat (Mercruiser 140hp inboard), under the waterline throug the back to the ouside, where its connected to the switch. The original wiring was shortcutted inside the boat, which means that the stern can come up too high. If I hit the switch accidently, things can get ugly.
Does anyone know how i can replace the wires? It looks difficult becaus its under the waterline.

They are a challenge but it can be done with the drive on. The wires go through the transome above the gimble bellows, there are 2 screws that hold a plate on remove the plate and the wires will pull out with the white gromets. Make sure you tie a string or wire to the oul wires from the inside to pull the new wires back in.

The limit switch is sold with a trim sender as well so you can replace both at the same time.