Looking for spray sealant with a nozzle

?? As I desribed above, one side of each tube is the boat superstructure, thus the tube doesn't have an end to wrap heatshrink around. Not to mention that there's gaps between the cables that heat shrink won't cover (bundle of round cables).

Yes, I'm aware that could be an issue.

Only on three sides, the third side, as I said is the boat superstructure and is the outside of the boat and is thus inevitably cold when the weather outside is cold.

Yes, I'm wondering if this may be the best approach, it can simply drain down to the bilges, the quantity is insufficient to be a problem there.

Some places elsewhere in the boat get wet from condensation but aren't an issue because there's nothing important below when they drip. It's just this one location where it's above a work surface.

Is that internal? ie something like square electrical trunking made of metal running along the interior wall, but in thermal contact with the outside?

Is the condensation coming from moisture inside? eg you descend to the cabin in your wet sou'wester and thus convey water into the cabin. The cabin is warm so that makes humidity. Or you're boiling things on the stove and that creates steam.

ie this thing is causing a cold bridge which is why you get condensation.

If you insulate the three sides, presumably the trunking becomes 'cold' (matches the outside temperature), but that's ok if it's protected from warm moist cabin air meeting it. Would need to prevent cabin air flowing into it, but if they're stuffed with cables that's not so hard - and gaps could be stuffed with some flexible insulation of some kind.

Theo