What is your snubber - and why

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Neeves

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I suspect we have thrashed to death the reasons behind snubber use and I think there is a hard core of members who believe in their use.

We have slowly increased the length of our snubber, installed as a bride as its for a cat, to a possible 30m and we are using 12mm dynamic climbing rope - in fact have just bought 2 x 30m of new rope. On reflection I have wondered if 12mm is the optimum, 38' x 7t cat, and maybe we should have optioned 10mm. Our bridle is attached to the chain with a custom made hook. This led me to wonder what others had decided was their optimum and whether they had 'played around' with the variables of length and diameter (even cordage type). Our bridle obviously will seem long - has anyone wanted to extend their snubber - but thought people might laugh - so you kept it 'short'.

So what do you use, how did you decide on that combination (of diameter of snubber vs length), how do you rig it and how do you attach to the chain. To make this useful for any, or all of us, what are the stats on your yacht. Finally - having settled into your anchorage, chilled chardonnay on the cockpit table and the wind picks up - unforecast - how easy it for you to extend your chain by, say, another 10m (assuming you have plenty of room in the anchorage).

Jonathan

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And why do I ask

I see some snubber vs yacht spreadsheets - but little supportive documentation. I read forum posts of owners snubbers and there seems no pattern - almost as if, 'I had 8m of 14mm - so I used it'. This latter would be true of cats, 'the bridle was supplied - I use it' - 'No, I never thought that it might not be ideal'

I wondered if there was a better way - like a compilation and distilling of experience.
 
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About 10m of retired dynamic climbing rope, 11mm iirc, going back to the midship cleat on a 12m boat - first try it blew 40 kts, its very stretchy! In my experience that sort of rope is either 11ish mm or 9ish, they dont usually, in the UK anyway, come in the same sizes as boat rope
 
RobbieW said:
About 10m of retired dynamic climbing rope, 11mm iirc, going back to the midship cleat on a 12m boat - first try it blew 40 kts, its very stretchy! In my experience that sort of rope is either 11ish mm or 9ish, they dont usually, in the UK anyway, come in the same sizes as boat rope
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Climbing ropes come mainly in 9, 9.5, 10, 11 and 12mm
 
I have, approx 3m samples of 8mm, 10mm and 12mm 'climbing' rope and bought 2 x 12mm x 30m lengths. I also arranged to ship for a friend 2 x 14mm x 30m lengths of rope to the same construction. His catamaran is 50'. As far as I can ascertain you can have any size, diameter, of rope you want to a standard kermantle construction. It will not necessarily meet a climbing rope specification. as they will not test, or the tests are irrelevant, but can provide UTS and extension to break - which is the data, I think, we need.

My 12mm and the 14mm has a focus on elasticity and ultimate strength - not on the standard tests for climbing rope. I have yet to test any of the rope for abrasion.

Previously we used re-cycled 12mm climbing rope around 15m lengths and then discarded these ropes in favour of recycled 30m lengths. Once we were comfortable with the 30m lengths - we invested in the new ropes. The new ropes have an eye sewn at one end, only. We are testing the eye - by using the ropes.

We ran the 15m ropes from the transom, our deck length is approximately 10m. The new ropes we have we arrange with an intermediate turning block which restricts the 'extension' beyond the bow to a maximum of 10m - normally the bridle would only extend 3m beyond the bow and we would actually only use about 16m of rope, each arm. If we are anchored in swell and/or chop and gusty winds we can use almost the full 30m. Basically we are using a 'mixed' rode but the rope and chain are joined by a hook, or in our case a bridle plate. So - its a mixed rode, but we can vary the length of chain deployed and instead of a splice join we have a moveable hook. Under normal usage the bridle plate even in calm conditions is only a couple of feet below the surface, no chance of dragging on the seabed.

Because our bridle arms are long if we have deployed a minimum of rope initially and then conditions deteriorate we can deploy another 10/15m of chain and simply deploy more rope, no need to retrieve the chain, take hook/plate off chain, deploy and then re-attach the hook. We can do all this from the cockpit

As mentioned the ropes are stretchy (compared to most rope used on a yacht) but unless you actually look - we don't notice that the cat is moving, with the stretch. I have therefore wondered if 10mm would have been sufficient. I have searched for any background to choice of snubbers/bridle but though there are some recommendations and spread sheets there is little, or no, quantitative data to support the recommendations. I was not expecting quantified responses - I had thought there might be some useful experience that people might be willing to share.

Our usage is for a cat, using 6mm chain, but you could use the same system, a mixed rode (of any chain size) allowing a variable length of chain deployed, for a single line snubber on a monohull.

Jonathan
 
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rotrax said:
Just to be perfectly clear, our snubber is about 7 metres of three strand spliced to a chain hook.

It came with our previous boat and we kept it for the current one.

We use it purely to take the load off the windlass.
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Mine is about the same. It also stops the noise of the chain in shallow water as I only have 20m of chain and about 60m of rope. Anything more than a lunchtime stop the load is always taken of the windlass.
 
NormanS said:
Jonathan, I wholeheartedly agree with the first half of your first sentence. ?
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Neeves said:
I suspect we have thrashed to death the reasons behind snubber use............




.............And why do I ask
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Is it because the “Never Splashed Colvic”and the “Steel Boats” trolls have died a natural death so it’s now time for a new one ?
 
18t ketch ( in cruising trim) using a 12m snubber made from 3 strand 15mm line, spliced loop on inboard end on foredeck cleat and spliced chain hook on outboard end. Not needed to extend the chain in 50kt gusts recently since we already had scope of 7:1. We have extended the scope and snubber by simply pulling some chain in so we could unhook the inboard end and add more rope. Being a ketch we dont veer like lots of modern sloops so adding more snubber length is unnecessary
 
On a 20’ Bay Raider, we use 5m chain plus 25m of nylon 3 strand which is fine. Anchor with centre board up regardless of water depth, but tend to anchor very shallow.

clearly the above does lead to some shearing about and the engineer in me wonders how much the shearing is down to where we make the rode fast, a cleat just forward of the shroud chain plates. If the centre of drag (be it wind or tide) is on the centre line of the vessel, securing the rode to anywhere thatisn’t on the centreline will set up a couple (ie drag force is not colinear with rode tension force) which is going to cause a moment generating yaw. So if you have a snubber or indeed an all chain rode cleated off away from the centreline do you more shearing about than you would on say Samson post in the middle of the foredeck?
 
7 ton 10.5m sloop. I use a chain hook spliced to a 4m length of 12mm nylon multi plait which is attached to a bow cleat. This serves for 95% of the time to take the load off the windlass and quieten the chain. For very strong winds, violent gusts or poor holding I extend the snubber with a 20m length of very stretchy 8mm three strand nylon attached to the plait with a double sheet bend. I find this method convenient, flexible and effective.
 
I've worked with Neeves on this. I have 4 answers:

1. PDQ 32. When I first changed to all-chain, I used the polyester bridle the boat came with, which the PO had used with rope rode. The first night there was some breeze (just 20Kt and well protected), I didn't like the tugging,and so I sat down and spliced up a nylon bridle from some 1/2" 3-strand I had in a locker. It was 100', so I went with 2x50' legs. I figured the extra length might be good for something, but I didn't deploy it or cut it off. Good thing.
2. I thought through the math, considered Neeves' ideas, and went to 8mm retired ice climbing rope I had (2x50'). Very soft ride. I anchored the ends to the stern cleats and rigged a very low chafe path over the bows. When the wind came up, I would move the anchor points to the bow, gaining 30' of scope. That was usually enough to take me from 5:1 scope to 7-8:1 scope. When the wind is strong you worry less about boats swinging differently--they are ALL straight back.

How did I move the ends, which were spliced? Easy. There is enough stretch that on a 32' cat you can get them loose with a sharp yank, timed for a lull. You only need ~ 6 inches. Alternatively, I could have motored just enough to lighten the strain. But I never needed to. On a larger cat I would cleat the ends instead of using eyes. Easy.

And you have pleanty of time to move the ends, so long as you walk fast. The boat does not drift that fast.

3. I started using a mooring some, so I reverted to the 1/2" bridle, for better peace of mind when away from the boat, but this time anchored it to the stern cleats, like the 8mm. Also pretty soft. In fact, the 8mm would have been fine, as it never showed any wear and load testing confirmed that at 50 knots I was not exceeding 12% WL. But I like to experiment. The 1/2" was also easier to handle than 8mm. Better grip. So I never switched back. The 1/2" stretched enough for me. But technically, the 8mm was the correct size, the 1/2" was just easier to grip. The point here is that there are a range of right answers, so long as the snubber is LONG.

4. F-24. My trimaran uses a rope rode. This may be counter intuitive, but I went to a Dyneema bridle. You see, nylon rode can be too stretchy, I already had enough stretch, and a Dyneema bridle does not distort (stretch to one side) when loaded from one side. The Dyneema bridle is more stable and lighter. But I would NEVER do this with chain.

Would a non-strech (Dyneema or other) rode work with a nylon bridle? Interesting. But since I can't grip Dyneema, I can't use it. In fact, I went up to a 1/2-inch nylon rode, which is monsterous overkill, because it is easier to grip. And it will wear forever. And it streches just the right amount (3/8" was a little too stretchy when I had a lot out). And I had it. It's an unusual combination (oversized nylon and a Dyneema bridle), but it works great.
 
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6ft of 10mm three strand nylon with a chain hook. Only really used to keep the chain quiet. If I ever really needed it I would add another 6 or 7 meters of 10/12mm octoplait and bring it back to the cockpit winch and cleat. Stag 28.
 
I believe people are overthinking this. I have a simple rule, you the same rope thickness you use for your mooring lines. if you trust your mooring lines (that will endure a much larger snatch load) why not use the same rope for your snubber?
I use 2 octoplated mooring lines in a V as a snubber belayed on the bow cleats and I have anchored in 40+ knots wind for 4 days straight. the lines were still in good condition after that.
 
Norman,, Why don't we wait for the the book, should be out soon with the amount of data he has been gathering. Surprised wikileaks haven't been in contact :unsure:
 
Pete7 said:
Norman,, Why don't we wait for the the book, should be out soon with the amount of data he has been gathering. Surprised wikileaks haven't been in contact :unsure:
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Books are so very 20th century.....

If has to be on a internet forum in a minimalist 'read bite' preferably with some pretty pictures or no-body reads it.

If you are waiting for a an easily digested summary - you will have a long wait. Many of my threads, like this one, on YBW are for my education, if you want to learn - stop complaining the topics don't interest you :) when you obviously read them.

Jonathan
 
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About 3m of 14mm nylon three-strand with a standard (Wichard?) chain hook on one end. It is short because I use it solely to stop the chain banging from side to side of the bow fitting in strong winds: I have never had an issue with snatching at anchor. It's 14mm because Nancy Black's in Oban had run out of 12mm.
 
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