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Old 02-10-2012, 20:41   #31
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Re: What size for snubber?

cfarrar; the loads on each side should be equal.
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Old 02-10-2012, 21:18   #32
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Re: What size for snubber?

I used up to 10m of 5/8 3 strand for a 15T boat, and would occasionally break a snubber if it was really snotty and I had a season or two of chafe and sun damage. My secondary anchor was on 3/4 inch rode, but I liked the extra stretch.

The main reason for the snubber is to cut down the snatch loads that are likely to break out your anchor if the holding is marginal.
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Old 02-10-2012, 22:23   #33
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Re: What size for snubber?

Nylon stretches 30%, it might be 25% under full load. So 10m of nylon under its maximum load will stetch, 25%-30%, amybe 2m-3m - I suspect it then suffers permenant deformation (creep) before it actually breaks. The chances of anyone loading nylon to its maximum load is around zero. Correct me if I'm wrong but I think 10mm nylon breaks at about 2t. The maximum load you are lilely to encouter on a 45' production yacht will be 500kg - and even this is pretty extreme (beyond 500kg we are thinking of hurricanes etc).

The nylon will only break if its old (and I'm not sure how age impacts elasticity) or its grossly undersized and one might undersize to get higher eleastcity for a given load.

Elesticity depends on how the rope is made, hawser is different to braided, which is differento anchor plait. But think in terms of 1/4 of the 25%, so maybe half a metre. And this is why you need it to be long - if its not 10m there is not enough to stretch anything meaningful.

Someone will undoubtedly be able to correct the actual percentage of elasticity and the load under which each size of nylon breaks. I'm just offering something from the depths of my memory, and its very deep but not necessarily full of accurate recollections
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Old 02-10-2012, 22:48   #34
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Re: What size for snubber?

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Originally Posted by over40pirate View Post
While cruising for 7 years (East Coast US, West Coast FL and Bahamas, I never used a lot of chain. (15' - 20' on each anchor) Anchored in 2 Hurricanes with no problems. I believe in rode stretch for absorbing shock loads, so as not to yank the hook out.
If I was doing it again, I would use 50' of chain and the rest nylon. I used an all chain rode, and had to deal with snubbers, and it was a pia. With 50' or less, you always let out enough rode to have the nylon to absorb shock, and noise. If it starts blowing, just let out more rode. Done.
If I was sailing around the world (which for some reason, a lot of sailors feel they need to equip there boat, as if they were) I would carry at least 1 all chain rode.
Just my .02
It's a good solution with a lot going for it. No snubber is one benefit. Another benefit is less weight in the bow. I use all chain - 330 feet of 1/2" chain, about 800 pounds of it - for only one reason - chafe.
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Old 02-10-2012, 22:51   #35
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Re: What size for snubber?

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Dockhead, you have probably thought of this but do you have a place where you could put a block to gain a fair lead? Blocks tend to do quite well in chafe because there is almost no relative movement between the sheave and the line and they provide a decent radius. The trick is having a strong attachment point in the right place for it to work. Just a thought.
Thanks - it's a good idea and I'll try again to find a place to attach a strop.
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Old 02-10-2012, 23:13   #36
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Re: What size for snubber?

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Thanks - it's a good idea and I'll try again to find a place to attach a strop.
Try one of your bow cleats (I'm guessing you have one on each side), they should be designed to take the load. We use nylon webbing for ours (it lies flat).

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Old 03-10-2012, 09:16   #37
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Re: What size for snubber?

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Evans,
I thought that a side benefit of a snubber was to prevent the noise of the chain dragging sideways on the bottom from being transmitted to the hull.

If the snubber is connected to the chain on the deck, then any noise should be transmitted by the chain to the bow roller. Did you notice anything?

Alain
I don't notice a lot of chain noise from the bottom, with or without snubbers. It may be because our bow rollers are urethane on UHWM bushings (eg its all noise damping 'plastic'), and/or because we have two watertight bulkheads between our bunk and the bow roller/chain locker.

With this 'deck snubber' set-up there is a bit more noise (than with the conventional over the bow snubber) when the boat is sailing back and forth and the chain chain fetches up against one side of the aluminum roller cheeks or the other. I could probably reduce that by putting large UHWM washers on the sides on the rollers to prevent the chain from hitting the aluminum. But at least so far its not bothersome enough to worry about.
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Old 03-10-2012, 09:24   #38
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Re: What size for snubber?

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Do you have a chain stopper of some kind, besides the snubber? I would certainly want something besides the snubber protecting the windlass from the loads.
No. I have never had a snubber break. But in big storms I do occasionally back up the snubber (to protect the windless) with a dyneema tie thru the chain to a spare tang I happen to have near by on deck.

I have never really liked the concept of the metal chain stoppers. They seem like they might sometime stop me from quickly releasing the chain in an emergency (if say the windless is out of action) and they seem like they would be exposed to (and the small deck area they are mounted to) severe shock loading. I prefer using rope.
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Old 03-10-2012, 10:30   #39
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Re: What size for snubber?

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No. I have never had a snubber break. But in big storms I do occasionally back up the snubber (to protect the windless) with a dyneema tie thru the chain to a spare tang I happen to have near by on deck.

I have never really liked the concept of the metal chain stoppers. They seem like they might sometime stop me from quickly releasing the chain in an emergency (if say the windless is out of action) and they seem like they would be exposed to (and the small deck area they are mounted to) severe shock loading. I prefer using rope.
I agree with you about metal chain stoppers.

I have had a snubber break, and having one come untied or chafing through is also imaginable. So I make it a rule to always belay the chain independently of the snubber.

Before I rigged up my stainless chain thing, I used a simple nylon strop with a spliced eye in one end and a chain hook on the other, something I picked up at the Southampton Boat Show years ago. That damned 9.99 strop saved my life, I think, when my snubber broke in a storm which blew up, wind veered 180 degrees, and I found myself anchored off a lee shore -- it was awful. I only discovered the broken snubber the next morning -- and I realize my error in not checking the snubber during the night.
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Old 03-10-2012, 11:04   #40
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Re: What size for snubber?

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Originally Posted by Dockhead View Post
It's a good solution with a lot going for it. No snubber is one benefit. Another benefit is less weight in the bow. I use all chain - 330 feet of 1/2" chain, about 800 pounds of it - for only one reason - chafe.
I've wondered the same thing. I have 70' of chain backed with nylon on my primary rode. I have not used a snubber, but I thought that I was remiss in not having one to take the strain off of the windlass. I've been through some significant wind and some rolly anchorages and held fine so I am comfortable with the amount of chain I have. I always let out the full length of chain anyway then some line depending on depth to get a decent scope. Even in 10' of water, I always have at least a 5-1 scope with the 70' of chain out. I don't imagine I would ever use less rode than that unless it was just for a lunch stop.

So, should I use a snubber to only take strain off the windlass, even if I don't need one to add stretch to the rode? Is this a serious concern?

Scott
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Old 03-10-2012, 11:11   #41
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Re: What size for snubber?

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Originally Posted by s/vPainkiller View Post
I have 70' of chain backed with nylon on my primary rode.

So, should I use a snubber to only take strain off the windlass, even if I don't need one to add stretch to the rode? Is this a serious concern?

Scott
Most people with chain/rope rodes put the rope rode on a cleat, so the load is on the cleat rather than left on the windless. That's easier than putting on a snubber.

However a snubber does give you a little redundancy at the bow roller chafe point. If you have a snubber and it chafes, then you still have the rope rode to hold you. While if you just have the rope rode, if it chafes thru you are adrift.

In any case, most yacht windless manual say that they are not designed to holding anchoring loads (usually they say something like "they are only designed to pick up the anchor"). So it is useful to take the load off the windless even if you have a rope rode.
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Old 03-10-2012, 11:17   #42
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Re: What size for snubber?

Quote:
Originally Posted by s/vPainkiller View Post
I've wondered the same thing. I have 70' of chain backed with nylon on my primary rode. I have not used a snubber, but I thought that I was remiss in not having one to take the strain off of the windlass. I've been through some significant wind and some rolly anchorages and held fine so I am comfortable with the amount of chain I have. I always let out the full length of chain anyway then some line depending on depth to get a decent scope. Even in 10' of water, I always have at least a 5-1 scope with the 70' of chain out. I don't imagine I would ever use less rode than that unless it was just for a lunch stop.

So, should I use a snubber to only take strain off the windlass, even if I don't need one to add stretch to the rode? Is this a serious concern?

Scott
Look at it this way - if your chain is not firmly attached to your boat, what is to stop your boat from being blown onto the rocks? Your windlass will not hold the chain, even if you don't mind breaking it. Is one snubber enough between you and being smashed on the rocks? Not for me. I use my snubber to absorb snatch loads; for firmly attaching the rode to the boat I use separate and independent means.

For a snubber to work it is sized smaller than your anchor rode and does not have nearly the strength of the rest of your ground tackle. Your means of belaying the chain should be equal in strength to the rest of your ground tackle - your snubber is not up to that.
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Old 03-10-2012, 11:42   #43
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Re: What size for snubber?

Scott,

I also use a chain/rope combo (100' chain). In order to protect the nylon rode where it passes over the anchor roller, I often use a snubber: a dyneema strop on the rode with a kleimheist, then the snubber attached to the strop. Cleat the snubber and the rode. If it's a well-protected anchorage I sometimes just cleat the nylon rode and use some velcro-style chafe gear at the anchor roller, just in case.
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Old 03-10-2012, 11:46   #44
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Re: What size for snubber?

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Originally Posted by estarzinger View Post
In any case, most yacht windless manual say that they are not designed to holding anchoring loads (usually they say something like "they are only designed to pick up the anchor"). So it is useful to take the load off the windless even if you have a rope rode.
Thanks, Evans and Dockhead. That's kind of what I was thinking. It falls under the heading of "prudent seamanship"....

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Old 03-10-2012, 23:46   #45
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Re: What size for snubber?

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Originally Posted by klem View Post
Dockhead, you have probably thought of this but do you have a place where you could put a block to gain a fair lead? Blocks tend to do quite well in chafe because there is almost no relative movement between the sheave and the line and they provide a decent radius. The trick is having a strong attachment point in the right place for it to work. Just a thought.
Rather than using a block, I put the snubber through a large shackle. I had a sheave made from a piece of left over nylon stock bar which fits over the shackle pin.
Dockhead, thanks for the tip on using a stopper fixed to the staysail chain plate.
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