kubark42

Sealing dyneema rope in a thru-hull

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I have a dyneema strop (like what Ropeye makes) which is going through a thru-hull. What is a good way to do seal this? Epoxy seems too stiff (it's rope after all) and glues in general won't stick to dyneema.

For info, when the boat heels the thru-hull will be below the waterline by an inch or two.

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Best way to seal the through-hull would be to close the sea cock.

Sorry, but I just can't wrap my head around what you're trying to accomplish.

Why exactly is it you have a strop coming though a through-hull fitting?

Above, or below the waterline (I know, stupid question)?

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I learned this is called a "soft padeye". There's a bunch of people discussing it, but not much feedback on sealing them. In my system, the soft padeye is mounted on a plate in a daggerboard trunk, and winds up being a few mm above the waterline when the boat isn't sailing, and just a few mm below when it is. I guess I'll play around with butyl, toiletbowl rings, and other flexible sealants and see what works.

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3m 5200. Put gloves on, mask anything you don't want it on and work it through the fibres and then fill around the strop. 

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Maybe it's just me, but I gotta wonder if a dyneema "soft padeye" that's run through a through-hull fitting that was never intended to take heavy loads and that then needs to be sealed with 5200 or something similarly permanent so it won't sink the boat is really a better solution than just installing a proper fucking padeye. 

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Maybe there are too many assumptions going on here.

It's not a thru-hull for a stopcock, it's just a 5/32" hole which is "through the hull" as opposed to "through the deck". Dunno about other boats, but a little bit of weepage through a downhaul mounting plate while heeled to port won't sink a trimaran. It'll just make more of a mess than I want to clean up every few weeks.

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Yeah, you're right. I was assuming that when you used the term "thru-hull" in your original post that you actually meant "thru-hull".

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I have one on my foredeck that I installed threaded side up and used heat shrink, although that was with threaded rod.

5200 may work but I would try G/Flex epoxy first.  It is almost as flexible as 5200, I think sticks better, will certainly seal better and will be a lot less messy.  That said I suppose I could envision it wicking into the fibres more and maybe making a hardspot?  Removal would involve a little heat but nothing too extreme.   

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The Ropeye loop is sealed so water cannot go from the rope side to the other . they are sealed so you drill a hole and install the ropeye with epoxy and the water is kept out. the simple type with a knot on the back will not work to keep water out. Ropeye-under.jpg

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1 hour ago, Tom Keffer said:

Another solution, courtesy of "Haligonian Winterr": 

 

Thanks, that was exactly what I needed! Combining this with the underside picture @Overboredshared, I think I have a very clear idea of how to do this.

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I have made a few of these. Get 2 pieces of wood and drill a hole in one that's a tight fit for your loop and cover both in packaging tape. Cut out a bunch of glass or carbon circles, half with a hole in the middle. Poke your loop through the wood and the wet out reinforcements with the holes. Fray the dyneema out over the whole surface of the reinforcement and put a little slightly thickened epoxy on them, then lay the rest of the wet out circles on top. Clamp the other piece of wood over the top til dried, trim to shape.

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15 hours ago, kubark42 said:

Thanks, that was exactly what I needed! Combining this with the underside picture @Overboredshared, I think I have a very clear idea of how to do this.

Just make sure if you're gluing them on, you use legit epoxy. Thickened West can work, but G/Flex or SpaBond equivalent is better.

 

HW

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I'm wondering is the color coated dyneemas have adhesion issues with epoxy.

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1 hour ago, IStream said:

I'm wondering is the color coated dyneemas have adhesion issues with epoxy.

ALL dyneema has adhesion issues

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Yes, I understand that. I'm wondering if the color coating makes it worse.

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3 hours ago, IStream said:

Yes, I understand that. I'm wondering if the color coating makes it worse.

Colour not measurably, heat-set certainly.

 

HW

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As usual, over complicating.....  if they have a disk backing (glass or carbon) just put them thru the drilled hole (assuming monolithic, not cored) and use a wedge of wood to load them as your sealant of choice dries.  You are done.  

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On 8/18/2018 at 3:42 PM, Alcatraz5768 said:

I have made a few of these. Get 2 pieces of wood and drill a hole in one that's a tight fit for your loop and cover both in packaging tape. Cut out a bunch of glass or carbon circles, half with a hole in the middle. Poke your loop through the wood and the wet out reinforcements with the holes. Fray the dyneema out over the whole surface of the reinforcement and put a little slightly thickened epoxy on them, then lay the rest of the wet out circles on top. Clamp the other piece of wood over the top til dried, trim to shape.

Am going to make a few of these, hopefully its as easy as you make it sound !!

Am wondering if any other type of rope fibre have reasonable UV characteristics, and bond better than dyneema? Its a very short loop, and in my application is only going to see 100kg or so of load, so stretch not much of an issue.

 

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You want the rope to be really tight in the holes in the wood so resin doesn't work up the fibres. Keep the rope side up so gravity helps. Make a few glass ones and pull them apart to see how they break, therefore how they work. 

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What kind of lifespan before the UV gets to them? 

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we use pro-set, works great.  

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On 10/1/2018 at 3:37 AM, Nodrog said:

Am going to make a few of these, hopefully its as easy as you make it sound !!

Am wondering if any other type of rope fibre have reasonable UV characteristics, and bond better than dyneema? Its a very short loop, and in my application is only going to see 100kg or so of load, so stretch not much of an issue.

 

Vectran may be an okay choice. The bond may be slightly better with epoxy but generally Kevlar just gets trapped in epoxy (poor chemical bond) much like the method discussed here for the dyneema/carbon disk. 

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if you have any uv concerns at all don't use vectran... whatever strength you gain from improved bonding over uv treated spectra (i think all the brand name uhmwp line is treated) you'll lose after 15 minutes in the sun as the vectan turns into weird dust before your very eyes... 

and yes, i had a bad vectran experience once so I'm probably biased...

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