Hi all!

I have good reasons to believe my (carbon) mast is not fully sealed. This makes capsize recovery way harder than it should be. I took one naive stab at sealing it, by poking silicone at all the rivet holes and other openings. Didn't improve things much.

So, planning to take the mast down again, and want to get it right and not have to do it again for a while.

Recommendations? Thoughts?

Also, anything else that might help mast flotability & capsize recovery? I'm already doing quite a few things

- packing and using a righting bag
- using a knot on the righting line, and hooking harness there, pumping w whole body, etc
- easing downhaul for max camber (carbon, bendy rig, laminate fullbatten sails)

If this wasn't a performance cat, I'd totally add a hobie mast ball

What kind of cat is it?

--
John

Nacra 5.0
CT
--

Whisper Catamaran

Images

find a pool. Dunk it.
That'll at least narrow your target areas.

Maybe its not leaking. What is your weight?



Edited by badfish on Mar 07, 2019 - 02:36 PM.

--
Joshua

Texas Gulf Coast
'82 Prindle 16 (Badfish)
'02 Hobie Wave (Unnamed Project)
‘87 Hobie 18 (Sold)
‘89 Hobie 17 (ill-advised project boat, Sold)
--

I sealed my mast in fall 2016 and it was still watertight in fall 2018. I wish I remember what I used as it has really held up good in the sun, etc. It was a clear adhesive silicone of some sort. I did clean the areas very well and then laid the top half of the mast in a lake for a while after sealing. I wonder if anyone has tried using some really high quality stuff like 5200 to ensure longterm adhesion/UV resistance.

When I sealed my A-Cat mast I used 5200 or maybe 4200. I tend to interchange them depending on what is open at the time-don't get me started on how the minimum quantity of 4200 and 4000UV is a 3oz tube that goes bad in about 3 months when kept frozen, and who has a freezer next to their boat shop? For this I would use 5200 black, or maybe the 4000 UV since its designed to be in the sun. Traphappy, find brand label of silicone!!

Anyway mast sealing is a tricky subject, best is to dip it in a pool or down at the beach on a flat day, you'll see the bubbles instantly if you have a problem.

Most masts aren't really just sealed, but have an air pocket built-in some how, i.e the top of the mast from the hound up is super well sealed with a bottom plug and a top plug. I suspect yours might not have this, but more likely you just aren't heavy enough to right the boat or often what happens to me on a high performance boat/foiler is you flip in a puff, puff goes away, you get your bows at 45 degrees to the breeze and the past perpendicular, you can get the tip clear but are still unable to get the boat upright due to a lack of breeze under the mainsail (think of water starting a windsurfer). If your mast isn't sealed you will turtle fairly quickly; doesn't sound like the case.

If you want more flotation, you could stick a chunk of pink foam (from home depot) that is coated in epoxy in the top of your mast, say 30" long. You don't want it to contact the side walls except at the very top where it gets completely soaked in 4000UV black to seal out the top of the mast. If it contacts the side walls you will inadvertently change the bend characteristics of the top of the rig which isn't ideal. No one has to know its there since its internal, and we don't run halyards etc. through our masts so life is generally okay.

Good advice on materials thanks!

True -- at ~82Kg I am too light to right it solo, but with crew and meeting the prescribed weight (and more), we can't without some outside help (ie: someone pull mast out of the water from a RIB). Once it's upright, it pisses water for quite a while out of the vent/drain hole at the bottom.

It was better (but not perfect) before a UV coating I had done, which involved removing and reinstalling fittings.

Later builds of the Whisper have a lighter mast. I've sailed them and they're light enough that I'd right it solo with some wind under the mainsail. I know because we capsized and the other guy (~90Kg) did it in blink before I could help him.

As much as I wish I had that lighter, and sealed, mast, working with what I got, and making it better...

Sam, the silicone was a home depot or west marine product. Next time I am at West Marine, I will ask them if I bought any in Sept 2016... They will know. The stuff has not yellowed and does not pull up along any of the edges if you pick at it. I am happy to not have to worry about a leaky mast this upcoming season or to go through the job of removing, cleaning, reapplying, testing. I will test on the water when I capsize....



Edited by traphappy on Mar 07, 2019 - 06:20 PM.

What does the manufacturer recommend for a bedding compound on a carbon mast?
I like 3M 5200 but I'm bedding stainless steel fittings on an aluminum mast. I can use a heat gun to remove the fittings.
I don't like silicone that much but when I do use it I go with Permatex RTV marine or 3M marine grade.
If you're pissing water out of the bottom of the mast it's not sealed.
I did leak detection with the mast base removed and the head of the mast lower than the base. I put the garden hose in the mast and filled her up. Water spewing out of the fittings told the tale.

https://www.hansonrivet.c…closed-end-blind-rivets/

I like closed end rivets.
I mask out the fittings and the area around the bed down with blue tape and goop it up real good.
At last check my mast held positive pressure.I have some new fittings to install soon so I'll see how it goes for the upcoming season.

--
'82 Super Cat 15
Hull #315
Virginia
Previously owned: '70 H14, '79 H16, '68 Sailmaster 26, '85 H14T
--

Quote

Once it's upright, it pisses water for quite a while out of the vent/drain hole at the bottom.

That does sound like a water intrusion issue. Back to the pool.



Edited by badfish on Mar 07, 2019 - 06:32 PM.

--
Joshua

Texas Gulf Coast
'82 Prindle 16 (Badfish)
'02 Hobie Wave (Unnamed Project)
‘87 Hobie 18 (Sold)
‘89 Hobie 17 (ill-advised project boat, Sold)
--

Compressed air and a squirt bottle with soap and water has worked on tires forever. For sealant any clear silicone outdoor sealer works.



Edited by mark-b on Mar 08, 2019 - 10:04 AM.

Tires have a Schrader valve installed. I would hate to split a carbon fiber spar by over pressuring it.That's not the stress they're laid up to counter.

--
'82 Super Cat 15
Hull #315
Virginia
Previously owned: '70 H14, '79 H16, '68 Sailmaster 26, '85 H14T
--

martin_langhoff

Good advice on materials thanks!

True -- at ~82Kg I am too light to right it solo, but with crew and meeting the prescribed weight (and more), we can't without some outside help (ie: someone pull mast out of the water from a RIB). Once it's upright, it pisses water for quite a while out of the vent/drain hole at the bottom.

It was better (but not perfect) before a UV coating I had done, which involved removing and reinstalling fittings.

Later builds of the Whisper have a lighter mast. I've sailed them and they're light enough that I'd right it solo with some wind under the mainsail. I know because we capsized and the other guy (~90Kg) did it in blink before I could help him.

As much as I wish I had that lighter, and sealed, mast, working with what I got, and making it better...

Dip it in the water and figure out where its leaking. Or you can remove and re-install all the fittings correctly, using 3M 5200.

gahamby

What does the manufacturer recommend for a bedding compound on a carbon mast?
I like 3M 5200 but I'm bedding stainless steel fittings on an aluminum mast. I can use a heat gun to remove the fittings.
I don't like silicone that much but when I do use it I go with Permatex RTV marine or 3M marine grade.
If you're pissing water out of the bottom of the mast it's not sealed.
I did leak detection with the mast base removed and the head of the mast lower than the base. I put the garden hose in the mast and filled her up. Water spewing out of the fittings told the tale.

https://www.hansonrivet.c…closed-end-blind-rivets/

I like closed end rivets.
I mask out the fittings and the area around the bed down with blue tape and goop it up real good.
At last check my mast held positive pressure.I have some new fittings to install soon so I'll see how it goes for the upcoming season.

We bed with 3M 5200. Waterproof, robust and provides additional reinforcement to the rivets.

gahamby

Tires have a Schrader valve installed. I would hate to split a carbon fiber spar by over pressuring it.That's not the stress they're laid up to counter.

If 5#'s splits a mast it was meant to go.

Ding ding. Carbon is pretty dang strong in tension and you are simply applying an even amount of tensile force to the inside of your mast. It could likely handle 50+ psi just fine, depending on how it was built (the seam is the weak spot). I think a high volume pump like used on a RIB is the way to go for pressure testing things, but honestly you'll see the bubbles the instant you dip it in some water with or without pressure; pressure just makes them visible for longer and might help if the leak is tiny. Also you can pretty much ignore the bottom 1/3rd of the mast if you think it is filling up as soon as you capsize, as generally that isn't in the water. So likely its the hound fitting or mast cap, though the shrouds are a possibility as well.

5# is read 5 pounds. Don't believe I'd use 50.

If all the penetrations are underwater he will find them, slowly. If there are penetrations underwater and one above, he won't. Air will escape out of the above water penetration.

A little air pressure and a squirt bottle of soap and water, easy.

Quote

Also you can pretty much ignore the bottom 1/3rd of the mast..

Don't think should ignore the bottom 1/3rd. Work on sealing both ends. My logic goes like this:

Take two empty plastic soda bottles. Drill a 1/4 hole in the bottom of one. Take both, bottom's up in to a pail of water...which one fills up first?

When you do a get a bit of water in your mast and your base is sealed...someone should invent a drain plug for the base!

--
Steve
Nacra Inter 20
Okemos Michigan
--

Yes I know 5#'s = 5 psi; definitely enough to find the leaks, my point was the mast can probably take a good deal more (I have a lot of experience with high tech composite pressure vessels, 5-100psi is nothing).

Fair enough Steve, my point was if the mast is filling up in a capsize then its likely up in the top 2/3rd. The bottom 1/3rd usually stays dry initially in a capsize.

https://www.widgetco.com/…00-rubber-stoppers-plugs