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 Post subject: Common mast leak points?
PostPosted: Thu Jun 23, 2011 7:56 am 
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Location: SE Michigan / NE Indiana
I was sailing solo a couple of weeks ago in some good air and a gust on a broad reach sent me over (I'm still trying to get over my engrained mono-hull instinct to come up on a gust with apparent wind in my face). Anyway, as soon as the mast hit the water I slid down the tramp and swam around to the daggerboard to try to hold it up, but to no avail. I'll be darned if the boat wasn't turtle in about 15-20 seconds. Fortunately a boater stopped by in a few minutes and we had the boat up quickly.

So, I'm thinking there has got to be a rather significant leak in the mast. I knew there was at least a small leak last year. When I was prepping the boat for winter storage, I heard a bit of sloshing and drained roughly a gallon or so from the mast. The water came out very reluctantly pulling a vacuum as it drained, leading me to believe whatever leak there was (at least in the aluminum portion of the mast) was rather small. I did a quick pressure check (it seemed OK), sealed a couple of small drill holes I found in the luff track below the rotation arm, and then sealed the hole I used for draining.

Now I'm wondering if the leak is in the comp tip. I'd think it would have to be a rather large hole for it to rapidly allow such a significant amount of water that the boat would go turtle so quickly. I assume the comptip is a separate cavity. My cursory inspection of it this spring revealed no obvious issues. Perhaps its already full of water? Where would a safe place be to drill a small inspection/drain hole? I don't want to weaken it!

So, to the subject of this topic, what are the typical locations for mast leaks?

I plan to put the boat on its side this weekend and do some further inspection - looking for air bubbles, etc. I store the boat mast-up on a cradle and will be without significant help, so I'd hate to have to try drop the mast and re-step it, but may have to consider that option as well...

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PostPosted: Thu Jun 23, 2011 1:14 pm 
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Location: Rapid City, South Dakota
The aluminium portion and the comp tip are two independantly sealed sections of the mast. 2 foam plugs in the alu part and 2 plugs in the comp tip.

I checked for leaks in my mast a few years back, and found that the peice of pipe that keeps you from compressing the mast, at the bolt for the mast rotation bar, was 1 mm too short and made a small gap for water/air to get into. Its not a common spot for a leak, but should be checked, just in case.

I replaced it with the correct dimension pipe, and sealed it with silicone. I also put a small dab of silicone on all of the rivits ont he mast, and its good as new now.

Its amazing what a small hole can do... Before I did this the boat would turtle almost immediatly after I flipped, and I would have an extremly hard time getting it back over, if I didn't right it quickly.


If I were you, I would un rig the mast, take it out into the lake, hold it underwater and look for air bubbles. Then take the mast rotation and pipe out, and use that as your drain/ air hole. Its the largest hole, that is already in the mast. I would then drain the mast, seal all the rivits you can find, and replace the mast rotation, making sure that was sealed as well. Then try the bubble test again.

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PostPosted: Thu Jun 23, 2011 3:39 pm 
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I was going to suggest that same spot. I broke the turn buckles on my diamond wires and in removing the bolt at the rotation arm I noticed it was an unsealed opening into the mast. When I put it back together I plan to seal up that opening.

Also I would not use silicone. Polysulfide sealants have a much better lifespan and reliability.

Geoff


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PostPosted: Thu Jun 23, 2011 5:00 pm 
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Location: West MI
I check my mast about every 2 years. With a sealed mast I find that my 18 still turtles easily. It must be the wind blowing on the tramp and the narrow top of the comptip, minimal flotation. I refuse to put a BOB on the mast but I am looking at other options for when I sail it solo.

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PostPosted: Fri Jun 24, 2011 6:09 am 
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Its been several years since I've had to mess around with the rotator bolt, but if I remember correctly, the bottom foam plug is centered around the bolt hole and the bolt passes through the plug, so the opening is sealed.

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PostPosted: Fri Jun 24, 2011 6:50 am 
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I pulled all the foam out since most of it was bad (mishaped, waterlogged) and am keeping the lower rivets and base casting un-sealed. I figure when its turtled, it'll fill only very slowly and since water seems to get in inevitably, it has a way out when upright. I heard water in the comptip also and drilled a hole to drain it, then sealed up well. That is a weight moment length that'll kill you.

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PostPosted: Mon Jul 04, 2011 12:31 pm 
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Quote:
I heard water in the comptip also and drilled a hole to drain it, then sealed up well.


Should I really drill a drain hole in it?


Last edited by MN_Viking on Sat Feb 11, 2012 2:15 pm, edited 1 time in total.

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PostPosted: Tue Jul 05, 2011 7:24 pm 
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MN_Viking wrote:
I can hear water sloshing around in the mast. Should I really drill a drain hole in it? Where?

Don't drill holes in the mast to drain it since that won't solve the leaking problem. Start by sinking the mast in the lake to see where air bubbles are coming out of it. After you find the leak, if any, or area where water is sloshing, drill out the rivets nearest the leaks/water sloshing with a 3/8" bit and drain the water through there, then replace the rivets with Hobie approved ones and seal them. Repeat until you've sealed all the leaks. Ask your Hobie dealer for rivets and for a recommendation of what tool to use to put them in with.


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PostPosted: Wed Jul 06, 2011 5:00 am 
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Location: Lake Champlain, Vermont
Good advice above. And you could see if it comes out the mast rotator bolt holes (likely) and drain it, call it a day.

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PostPosted: Wed Jul 06, 2011 8:04 am 
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Location: North Carolina
When replacing rivets in the mast use some rivet sleeves. The sleeves prevent the rivet mandrel from allowing a leak. A little silicone on the sleeve and its all sealed up. Mandrels will often fall out leaving quite a hole for water to enter.


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PostPosted: Sat Jul 09, 2011 1:24 pm 
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Quote:
you could see if it comes out the mast rotator bolt holes


Nope. No leak there.

Quote:
Don't drill holes in the mast to drain it since that won't solve the leaking problem.


I drilled the rivets out of the end cap at the top of the mast, and lifted it out. I drained a small amount of water, less than a gallon. The mast is totally hollow, I can see all the way down to a foam block that's around the mast
rotator.

Quote:
Polysulfide sealants have a much better lifespan and reliability.


I riveted the top plate back in and sealed it and all the other potential leak points with loctite poly sealant.

Now I'm ready to take it to the lake and submerge it to see if there are any bubbles.

Thanks for this thread and all the good advice!


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