comp tip mast leak

I have a H16 with comp tip (1989). It leaks and I can't find the hole.

I heard water in the mast last year when I took it down last fall, so I drained it all out and stored it in a barn for the winter. This spring I went around with marine silicone and sealed every joint/hole/seam I could find. I did the dunk test in the lake and saw no bubbles after the sail track filled.

I have not stepped the mast yet. I have the boat on the beach with the mast laying on the tramp, relatively horizontal with perhaps a small slope to the base. It rained a few times, and now I can hear water sloshing in the mast. Seems like it could be a couple gallons! There was water in both the top (comp tip) section and at the base. The water did not seem to travel freely between the 2 sections, I could hear it slosh and stop at the plug in the joint beetween the comp tip and the bottom aluminum section. There could be a small leak between the sections, don't know.

I drilled a small hole at the base and blew air in and tried to soap up the joint, rivet holes, etc. No bubbles. When I tip the mast to the base, no water comes out. When I tip it to the top water comes out along the grooves at the sides of the rubber sail track in the comp tip and somewhere under the pulleys at the top. It also drips from the bottom of the comptip sail track, where the joint is. (I tried to seal in there but I don't want a bead of silicone inside the sail track joint interfering with raising the main, so I went easy on that especially since I couldn't get my fingers in there).

Is that rubber/plastic sail track one piece? Should the grooves on either side where it attaches to the mast be sealed with silicone? What's behind it - is that where my leak(s) could be? Is it possible to replace just that piece? I noticed that one groove is wider than the other.

I know this is a recurring theme, but I've tried several previously suggested ideas and this is frustrating. I want to go sailing, but not with a leaky mast. And I don't want to have to pull the tip out - that seems like a big, messy, multi-person project. Thanks for any ideas.

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1989 H16
2009 H16 squaretop

H16 CompTip leak?

First... the CompTip is a hollow tube of glass cloth with a cosmetic and water barrior putty on the outside. The ends are sealed with 2 part foam. We have found that the foam plugs can shrink over time, so maybe reseal the ends.

Then the line down the front... is a mold part line that is (flashing) ground down. That line is also present under the luff track ( http://static.hobiecat.com/2010_archive/support/pdfs/38584001.pdf ). We now paint some resin over the area to seal it, but older ones are known to seep water through the glass in some cases. Matter of fact, seems they can suck in humid air and that can condensate inside the mast. Basically a mast on land can pump itself up with water. So, remove the track and paint resin over the mold part line for best sealing results.

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Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)

Excellent information! Thank you, thank you. I want to clarify that the "mold part line" is the vertical seam running the length of the comptip? You say that seam might leak? (I didn't see any water coming out of the line on the front of the comptip).

I'm not familiar with resin. Is the resin a Hobie product, or what should I use?

Assuming that the foam plug at the bottom joint of the comptip is good, and the water condenses inside the comptip (totally plausible in my experience), and we keep the boat mast up on the beach, then how do you recommend getting the water out? I drilled a small hole in the bottom of the mast to drain water (plugged with a set screw), but it seems like the water might stay up high.

It hasn't rained since I drained the mast a few days ago, but we have had dew I think. I'll go check the mast and report back about any water inside it.

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1989 H16
2009 H16 squaretop