I regularly use hot-melt glue to seal bundled wire cables, this stiffens the cable and makes if waterproof. I also use this methodology to seal antenna or any other coax connectors for radios.
This should work well on a marine VHF radio antenna connector. Just melt some hot-melt glue on the wire ends exiting the cable sheath, then use your favorite heat-shrink tubing to finish the job.
This also works for making your own sheathed cable if you use a long piece of heat-shrink.
Just remember, heat-shrink is pretty stiff, so only use it where you don’t need lots of flexibility.
I made a neon test light that was submersible using a neon bulb, clear heat-shrink tubing, and hot-melt glue.
Editor Comments – This sounds like a great way to make a waterproof seal on any wiring located in the bilge area of your boat. Or any area that might be susceptible to water intrusion or sea spray.
The added stiffness created by using the hot-glue method should not be a problem on a boat as long as all wiring is properly secured in place and not allowed to move even under extreme sea conditions.