If the radar
is on the mast
, you will probably want to cut the cable and put a terminal strip inside the boat so you can pull the mast
If the radar is not on the mast, take a look at the cable clam. If you can put the connector through the cable clam with the rubber seal removed, then you do it. The next step is to drill a cable-sized hole in the seal and slit it radially on one side with a razor blade so that it will go over the cable. Reinstall the seal in the cable clam and everything will get watertight when you compress the cable clam.