Looking at a spec sheet it stated your mast on the 380 is deck stepped.
Why not pass the wires down inside the mast and then through the deck in the mast.
That is what I did on my CAL. Here are images of the mast base. Drilled holes in the base to snug fit the small aluminum tubes. The tubes were seated in the mast base with 4200.
Large pipe for radar lead and electrical lighting wires. Small pipe for VHF coax antenna lead.
I attached flexible hoses to the pipes and passed the Radar and VHF wires (along with the electrical leads for lights) through the hoses and when setting the mast on the deck we made a loop so water running down the wires would drop off and collect in the base.
I made weep holes on the bottom of the mast to let the water run out of the mast onto the deck. Then I ran the Radar and VHF antenna into the cabin and up to the NAV station as a continuous lead. Should I have to remove the mast I will either cut the wire in the cabin or remove the leads in one piece. Doing it over again I would make the tubes and hoses a little bigger. We got the wire thru but it required a lot of pushing and lubrication. We guessed and we guessed a bit to small.
