Originally Posted by Rusty123
Those deck seals look sweet -- unlike my radar cable, my VHF cable exits the mast above deck, and then goes through a similar device.
But as I sit here thinking about it, it occurs to me that when I first removed the cabin headliner to investigate the leak, I pulled the slack in the radar cable into the cabin. I'm thinking that "slack" might have actually been a drip loop. so while I solved one problem (by removing the caulk in the mast drain hole), I might have caused another (by removing the drip loop). Hopefully, I can put the drip loop back in (I can certainly push the slack back in the mast, but it may take some work to form a loop).
This also makes sense in light of the fact that there is absolutely no evidence that this leak is long standing -- no stains, no deterioration, nothing, even though this boat has been weathering Pacific Northwest winters for at least 15 years.
One good thing about all this -- I was able to identify that the plywood coring forming the deck penetration is rough and raw, and needs to be smoothed and epoxy sealed.
A common approach to feeding wiring through the deck on a deck stepped mast was, at one point, the use of a tube that extends above the step for several inches and into the deck for several inches below the step with caulking around the tube at the deck penetration. Wiring was then routed down to the deck level within the mast and then looped back up to, and then through, the tube. (Some such tubes have a goose-neck arrangement looking like an inverted capital J.) The loop, extending below the top of the tube within the mast, is, in fact, a "drip loop" as you guessed. By pulling the wire entirely through the step, you likely did eliminate the loop. One solution might be to use an injectable, expanding, foam of the type used to insulate refrigerators, which is "closed cell" and will not absorb water, if you can get a small nozzle up and into the penetration far enough, it will fill the voids around the wiring and expand through the top of the tube somewhat, potentially preventing further penetration.