Dyneema sleeve to protect the snubber

[gauvins]

Experiencing an unpleasant night at anchor with strong wind and accompanying waves made me rethink our anchoring strategy. Up until now, it was 5:1 chain and a 24mmx2M rope tied to a Samson post in order to relieve the windlass. The reason being that setting a longer snubber did require acrobatics over the bow to get the chain hook unto the chain. Inconvenient if not dangerous.

So. I've moved to a 12M long snubber secured to the chain with a 12mm dyneema shackle. The line is a 16mm Lyros handy rated at 20% elasticity. The marketing blurb claims that the cover is extremely abrasion resistant. Still... I plan to add a short (< 1M) dyneema cover to protect the line as it goes over the roller and presumably chafes as it elongates and contracts while being pressed between the chain and the roller.

So my question is about how to splice the cover. If it is spliced fully milked (i.e. tight) it would introduce a stress point along the snubber. If spliced loosely (i.e. 15-20 % slack) the dyneema sleeve should expand/contract in harmony with the snubber. Loose is what I am planning to do, unless I am made aware of counter arguments.

Thanks

[Benz]

If you leave it loose, it may become baggy and bunch up and make retrieval or deployment awkward: that sloppy bit will dog you.
If you milk it tight, there's no earthly way you'll be able to milk it too tight. Remember that as the nylon stretches, the diameter decreases; so likewise with the cover. I'd pull it on there as tight as ever I could.
Another option is leather, which is far more abrasion resistant than dyneema sleeve.

[gauvins]

Originally Posted by Benz

Remember that as the nylon stretches, the diameter decreases; so likewise with the cover. I'd pull it on there as tight as ever I could..

Excellent point. Will do.

Originally Posted by Benz

Another option is leather, which is far more abrasion resistant than dyneema sleeve.

Interesting. Well, when the cover is worn out. Will try

[thinwater]

A snubber is wear item, like dock boards. A fancy cover is window dressing. Cover the wear are with a floating sleeve of tubular nylon or polyester webbing and replace the line every 1-2 years.



Coat the webbing with Maxijacket and it will outwear anything but chain.



Wear resistance has a LOT less to do with the material and the weave; you want tight and dense, the reason tubular webbing does well and is what is used on mooring pendants. And it is cheap through climbing companies.


http://sail-delmarva.blogspot.com/p/chafe-gear.html

[barnakiel]

Yes. Dyneema sleeve is fine. But any other sleeve nylon or polyester is 99% just as fine. You discard a worn out now and then and that's that.


Spectra sleeves are not too easy to source though. And seem expensivish (to me).



b.

[olddog57]

Originally Posted by gauvins

Experiencing an unpleasant night at anchor with strong wind and accompanying waves made me rethink our anchoring strategy. Up until now, it was 5:1 chain and a 24mmx2M rope tied to a Samson post in order to relieve the windlass. The reason being that setting a longer snubber did require acrobatics over the bow to get the chain hook unto the chain. Inconvenient if not dangerous.

Please explain: why over the bow acrobatics?
I just arranged a 9.5 m snabbing bridle with a chain hook in the end (not used yet). I think to set the anchor, to connect the hook, then to let go the chain for little more than the 1.2 bridle length - where is here any acrobatics?

[gauvins]

Originally Posted by olddog57

Please explain: why over the bow acrobatics?
I just arranged a 9.5 m snabbing bridle with a chain hook in the end (not used yet). I think to set the anchor, to connect the hook, then to let go the chain for little more than the 1.2 bridle length - where is here any acrobatics?

The hook typically falls off when going over the roller. So it means leaning over the bow "fishing" for the chain, or kneeling under the rail guard to secure it.

There are specialized chain hooks that can be secured on deck, but they are said to reduce chain strength by as much as 50%. A dyneema shackle seems to be a much better option.

[Dockhead]

Originally Posted by gauvins

The hook typically falls off when going over the roller. So it means leaning over the bow "fishing" for the chain, or kneeling under the rail guard to secure it.

There are specialized chain hooks that can be secured on deck, but they are said to reduce chain strength by as much as 50%. A dyneema shackle seems to be a much better option.

Or a rolling hitch. Why in the world do people use chain hooks, and then go through this nonsense? I never understood it. Rolling hitch onto chain behaves like a splice -- it's brilliant.



For chafe, why not just use a bow roller? You have more than one of them, right? That's what I do.


Another way to avoid chafe is an eye nearer the waterline, through the bow. That will give you the ultimate fair lead and no way to chafe on anything. Additional benefit is it increases the effective scope.

[olddog57]

Originally Posted by gauvins

The hook typically falls off when going over the roller. So it means leaning over the bow "fishing" for the chain, or kneeling under the rail guard to secure it.

There are specialized chain hooks that can be secured on deck, but they are said to reduce chain strength by as much as 50%. A dyneema shackle seems to be a much better option.

I see, thx

[powsmias]

Originally Posted by gauvins

The hook typically falls off when going over the roller. So it means leaning over the bow "fishing" for the chain, or kneeling under the rail guard to secure it.

There are specialized chain hooks that can be secured on deck, but they are said to reduce chain strength by as much as 50%. A dyneema shackle seems to be a much better option.

you might wanna try a mantus hook on that chain

[olddog57]

Originally Posted by powsmias

you might wanna try a mantus hook on that chain

This is what I have, and this Mantus should not loose its grip going over the roller, and I hardly see how it is able to reduce the chain strength.

[gauvins]

Originally Posted by Dockhead

Or a rolling hitch.

1. Risk of user error. We're summer sailors.
2. Not so easy with large diameter rope and limited clearance between the deck and chain
3. Execution speed could be an issue. We sometimes have just a few seconds to secure the chain while the boat backs up to set the anchor. Would not be fun to be caught with your hand under the chain when it gets loaded.

Originally Posted by Dockhead

For chafe, why not just use a bow roller?

We have two. Using the roller in line (i.e. where the chain goes) is precisely why I want to splice a cover. Using the other roller would mean going over the bow to secure the line to the chain.

[gauvins]

Originally Posted by olddog57

This is what I have, and this Mantus should not loose its grip going over the roller, and I hardly see how it is able to reduce the chain strength.

You may want to test this : https://www.practical-sailor.com/blo...e-12005-1.html

[Dockhead]

Originally Posted by gauvins

1. Risk of user error. We're summer sailors.
2. Not so easy with large diameter rope and limited clearance between the deck and chain
3. Execution speed could be an issue. We sometimes have just a few seconds to secure the chain while the boat backs up to set the anchor. Would not be fun to be caught with your hand under the chain when it gets loaded.. .

Well, some of my best friends use dyneema shackles for this There's nothing wrong with that, but risk of error with a rolling hitch, about the second simplest knot on the planet, approaches zero, and consequences are not serious. I am wrapping a 1" nylon rope around a 12mm chain and it's no problem on my boat.


But I'm curious -- why are you doing this before setting the anchor? The snubber attenuates the connection to the boat and makes it much harder to feel how the anchor is setting. Also, you really don't want to set the anchor at your final scope -- because again the catenary of the chain attenuates the connection and makes it harder to feel what's going on on the bottom. It's generally recommended to set the anchor at 3:1, more or less, then let out chain to your final scope after you're sure the anchor is well set (I back down for several minutes at redline, but I'm a bit of a fanatic and that might be overkill).


You do belay your chain first thing after letting out the initial scope, right? That's really important. Don't rely on a snubber to keep the load off the windlass -- it's not designed for that, and becomes a weak link. If you have a chain lock, always use that first. If you don't have a chain lock, then you can use a strong strop (it, and its connections to boat and to chain, should be as strong as the chain, in order not to form a weak link).

[Dockhead]

Originally Posted by gauvins

You may want to test this : https://www.practical-sailor.com/blo...e-12005-1.html

The article says that the Mantus chain hook reduces chain strength by 40%, and recommends using a "grip hitch" (e.g. rolling hitch) instead.


However, the article also quotes the president of Mantus as saying that snubber loads are too small to worry about this.



I agree with him. The strength of a wet nylon snubber of the size most of us use is a fraction of the strength of the chain. I don't see the slightest purpose of chain hooks, and don't understand why people spend money on them, but I wouldn't worry about point loading the chain with them.


The same point however should be a caution to anyone who does not belay the chain except with a snubber. You are drastically weakening the ground tackle system like this.