Seal Mast Head

How should the top of my mast be sealed (non-comptip, old style head)? I know the head/pully casting dosn't do it because I can see into the mast through the where hallyard meets the pulley. Is there something else at the top that seals it, or do the old masts just simply take water? Also, would this problem be solved by getting a new style mast head, or is there another obvious solution? Turtling is no fun!!

Thanks,
Texas Sailor

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1979 H16

There should be a foam plug glued inside the upper mast just below the casting. It may have shrunk or twisted allowing water to pass. Easiest solution is to inject a two part floatation foam into the area making a 1 foot long plug of foam. It has to be a marine grade foam... not some wall filler or something.

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

So there's no way to just seal the outside where the mast head pulley and the mast slide together?

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Zach

I just used the same silicone that I used on the rest of the boat for sealing.

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1982 H16 (C:\Worthy)
Yellow/White Prism type sails

Do not silicone the seam were mast head inserts into the mast. Water enters through the halyard openings (front and back) where the hayard goes over the sheave, so sealing at the seam does nothing.

The mast is sealed just below the mast head by a foam plug that is silcone'd in place. I have seen masts from the '70's and the foam plug seal is in great shape. It looks like when it was manufactured, the plug was dipped in a bucket of silicone and shoved into place.

To test if the mast is leaking, put in a pool (or lake) and see if and where bubbles are coming from.

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1980 18 foot class A Unicorn catamaran
1977 Super Sunfish (sold)
1979 Hobie (sold)
1983 Hobie 16 Hawiian Sunset (sold)
1981 Hobie 16 Tequilla Sunrise (sold)
2008 Hobie 16 (sold)
2023 Hobie 16
Founding member of the "San Dimas Yacht Club"
John

ok, thanks. Here's my plan and let me know if it doesn't make sense. First I'll silicone the crap out of all the rivets and fittings on the mast (excluding the mast head). I'm going to do that tonight because I don't have enough time to head over to the water and do the dunk test. Then maybe tomorrow I'll do the dunk test to see if my silicone job worked and to see if the mast head is leaking.

What kind of silicone should I get? 3M 4200 or 5200? I would like something that dries clear so that it isn't so ugly on my black mast.

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Zach

Before doing all this work, why not just put the mast in the water by itself and see if it leaks. If you force the mast under water, you'll see bubbles where it leaks, you just need to focus on those.

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Marc...
1978 Hobie 16 Keoke, sail# 36 84

Good point. I guess I'll just wait. All I know is it leaks pretty bad because it started to go under pretty quick when we capsized.

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Zach

Just do it right the first time and save yourself a headache later. Drill the rivets off and take the head off. Get inside and seal the area correctly. Get some stainless rivets and put the head back on. Make sure and seal the rivets. You'll thank yourself the next time you go over and it stays on the surface.

If the mast has been leaking, the first thing you need to do is make sure you get all the water out. You'd be amazed at how much mud can get in there, too, if you turtle on a shallow, mud bottom lake like me. This could be contributing to your rapid turtling.

Best bet is to remove/reseal the foam plug(s), then seal the other fittings (as needed if you do the leak test).

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Jerome Vaughan
Hobie 16

Don't forget to use top hats when re-riveting.

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'81 H16

If it ain't a blowin', I ain't a goin'