Snubber twisting the anchor chain - why?

[Goldie]

My current anchoring set-up is resulting in an issue I've never experienced before. I attach the snubber to the chain with a chain hook, pay out the chain until there's a reasonable bight and the snubber has the load on a cleat, and then go astern to set the anchor (so no load on the chain or windlass). When the load comes on the snubber, the chain hook and chain rotate several turns and whilst they turn most of the way back when the load comes off, I'm often left with a bit of a 'ball' which needs to be unwrapped by hand when the chain is recovered and before the chain hook can be removed - a bit of a finger hazard if there is any sea running. I've never experienced this on previous boats, so what is different? The snubbing line is 3 strand nylon, the chain 10mm and the gypsy is on a capstan (i.e. vertical axis as opposed to horizontal axis windlass). The latter is the only difference I can think of from previous boats, all of which had a windlass. Is this a factor? Does this induce some twist in the chain? Is there some sort of torque effect from the three strand? Constructive suggestions would be gratefully received.

Thank you.

 

[Motor_Sailor]

As the load comes on the snubber, the three strand rope will try to 'straighten out' and the far, unrestrained end will rotate. As the load comes off it will return to it's original position less a little lost as permanent stretch.

A solution is to use a snubber of rope made with a more 'balanced' construction - Kernmantle or Octiplait for example,

 

[Goldie]

As the load comes on the snubber, the three strand rope will try to 'straighten out' and the far, unrestrained end will rotate. As the load comes off it will return to it's original position less a little lost as permanent stretch.

A solution is to use a snubber of rope made with a more 'balanced' construction - Kernmantle or Octiplait for example,

My suspicion entirely, but I didn’t want to dive into buying 8 strand or similarl only to find that nothing changed. Thank you.

 

[Motor_Sailor]

Try putting a 'Wanted' notice up in the local climbing wall.
They often have pinboards where small personal notices can be put up.
Ask for an end of life 11mm climbing rope. It's the perfect stuff but you just have to guard against chafe.

Granite Planet Climbing Centre
Unit 10 Parkengue Kernisk Industrial Estate
Penryn, TR10 9EP

 

[oldmanofthehills]

+1 for Motor Sailor's suggestion. I use my old 11mm climbing rope which has plenty of elasticity. Indoor wall ropes often less stretchy so find an outdoor climber if pos

 

[Neeves]

We don't use the snubber to power set the anchor.

We have a 'chain lock' short strop of dyneema with a chain hook that we use to secure the anchor on passage and is our ultimate back up should the bride fail. The dyneema strop is attached to a strong point (not the windlass). We use this strop to power set - it has no stretch. If you use the snubber as you power set it simply stretchers, reduces the life of the snubber, and some of the energy of the engine is being used to stretch the snubber not power set the anchor.

3 strand nylon is fine as a snubber (and was used for climbing (those with maturity will recall Bridon's Viking No 3 and No 4) but this has been replaced by Kermantle, depends on yacht size 8mm, 10mm or 12/13mm. Kermantle is impossible to splice and takes an ugly knot - we sew eyes in the end using dyneema braided fishing line with shrink covers. Sewn eyes with shrink covers are common place on climbing rope.

Snubbers are about amount of stretch - if you source from a climbing gym (or buy new) go for length )you get more stretch). Don't cut it - use it all (whatever length you can source). There is an article in the July issue of YM on snubbers - try your local library or send me a PM (with a email address and I'll see if I can help). To use all the length - start the snubber at the transom then you use deck length before you go out board at the bow. Our snubbers, bridle, are 30m long.

If you Google Mathias Wagner, or search this forum, he has a neat calculator that underlines why you need length.

A short snubber, a few metres, or one that is too fat is a waste of time for snubbing.


I understand that indoor gyms are required to chop up their old ropes to ensure that are not used for height safety (and the short lengths then go to land fill - nothing like being envormentally savvy!). If this is true - the gyms still need to retire the ropes - book their next retirements and offer to support their coffee fund. I suspect climbing rope will survive in land fill for centuries

Jonathan

A commercially sewn eye with shrink cover.

 

[Motor_Sailor]

Indoor wall ropes often less stretchy so find an outdoor climber if pos

Yes, should have made myself clearer - this is to use the notice board at the wall to message active climbers for one of their dynamic climbing ropes, not to get an old rope from the wall itself which will be a less stretchy 'top rop'.

Or try a message on the forums of UKC - ( UKClimbing.com ) There's often people asking what they should do with tim expired rope. Often these days it will be nearer 10mm than the traditional 11mm, but it'll be fine. Still go a breaking strain of several tons. (22KN)

 

[Graham376]

I just let the chain pay out as we drift or motor slowly back, snub the chain, power set the anchor then attach the snubber (3 strand nylon) and feed a bit more chain out.

 

[Roberto]

an issue I've never experienced before.

With 3 strand rope, it depends on the construction/setting of the filaments in each strand. A number of 3 strand ropes will twist when under tension, some unbearably so (I had one significantly damaged by the chain wrapping and unwrapping), others will simply stretch with almost no twist. You may have gone from one type of 3 strand rope to another one with different fiber tensions. Personally I do not use 3 strand any more, in particular for long snubbers.

 

[Neeves]

With 3 strand rope, it depends on the construction/setting of the filaments in each strand. A number of 3 strand ropes will twist when under tension, some unbearably so (I had one significantly damaged by the chain wrapping and unwrapping), others will simply stretch with almost no twist. You may have gone from one type of 3 strand rope to another one with different fiber tensions. Personally I do not use 3 strand any more, in particular for long snubbers.

I would not use 3 strand nylon either but many people cannot access anything else, easily, and I'd rather people use 3 strand nylon (10/12mm) than many other cordages I see being used. We use 3 strand nylon for our second rode and it does not twist - I was unaware that, some, 3 ply did twist - we live and learn. Thinking about it - the 3 strand nylon for the second rode is the only 3 strand we have on the boat.

For a snubber you should be trying to source cordage that offers maximum elasticity (commensurate with sensible strength). It then becomes a compromise between elasticity (percentage) vs length of snubber. Using top rope, from a gym, is as good as dynamic as long as the rope is long enough. The advantage of the gym is they are more easily accessed for recycled rope (or they are in Oz).

We started off using 15m top rope, many gyms in Australia are not very high. I wanted longer snubbers as then the snubbers will last longer (having had short snubbers fail)) and you have more 'extension'. I found a gym using 30m top ropes and tried them - then replaced them with new dynamic rope 12mm and then moved to new dynamic 10mm - which seems fine (38' x 7t cat).



In our learning curve I finished up with an healthily large pile of recycled ropes and I regularly give pieces out to people unconvinced at the value of a snubber - who then become similarly evangelical

So if you believe in snubbers, are successfully are able to recycle a retired climbing rope and are offered 2 or 3 ropes - take them - and spread the word by offering to a neighbour in an anchorage when they invite you for dinner..... Tell them to search out the July 2021 YM for instructions .........

One reason we want the extra total stretch - we have downsized our chain from 8mm to 6mm high tensile - a decision b based on saving weight.

As mentioned - send me a PM and an email address and I'll give detail of how we arrange a 30m snubber and have only a few metres forward of the bow and we reduce snatch loads, manage yawing and chop.

We would never move back to heavy chain (8mm) and no snubber(s). We did look at 4mm high tensile chain but no windlass has a 4mm gypsy and using a drum winch might have worked (as used for wire) but was 2 steps too far, economic and simply outside my experience base.

Jonathan

 

[NormanS]

I would not use 3 strand nylon either but many people cannot access anything else, easily, and I'd rather people use 3 strand nylon (10/12mm) than many other cordages I see being used. We use 3 strand nylon for our second rode and it does not twist - I was unaware that, some, 3 ply did twist - we live and learn. Thinking about it - the 3 strand nylon for the second rode is the only 3 strand we have on the boat.

For a snubber you should be trying to source cordage that offers maximum elasticity (commensurate with sensible strength). It then becomes a compromise between elasticity (percentage) vs length of snubber. Using top rope, from a gym, is as good as dynamic as long as the rope is long enough. The advantage of the gym is they are more easily accessed for recycled rope (or they are in Oz).

We started off using 15m top rope, many gyms in Australia are not very high. I wanted longer snubbers as then the snubbers will last longer (having had short snubbers fail)) and you have more 'extension'. I found a gym using 30m top ropes and tried them - then replaced them with new dynamic rope 12mm and then moved to new dynamic 10mm - which seems fine (38' x 7t cat).



In our learning curve I finished up with an healthily large pile of recycled ropes and I regularly give pieces out to people unconvinced at the value of a snubber - who then become similarly evangelical

So if you believe in snubbers, are successfully are able to recycle a retired climbing rope and are offered 2 or 3 ropes - take them - and spread the word by offering to a neighbour in an anchorage when they invite you for dinner..... Tell them to search out the July 2021 YM for instructions .........

One reason we want the extra total stretch - we have downsized our chain from 8mm to 6mm high tensile - a decision b based on saving weight.

As mentioned - send me a PM and an email address and I'll give detail of how we arrange a 30m snubber and have only a few metres forward of the bow and we reduce snatch loads, manage yawing and chop.

We would never move back to heavy chain (8mm) and no snubber(s). We did look at 4mm high tensile chain but no windlass has a 4mm gypsy and using a drum winch might have worked (as used for wire) but was 2 steps too far, economic and simply outside my experience base.

Jonathan

What would you say about anchoring with a wire rope on a winch? Some years ago, I spent time cruising in a fishing boat in Prince William Sound, Alaska. That was the common practice there.

 

[Stemar]

Surely the simple, cheap solution would be to dig the anchor in before you set up the snubber?

If it still bothers you, make up a bridle snubber, one line through each bow fairlead. Even on my Snapdragon, that reduced the swinging in the wind, so win-win

 

[Neeves]

Nothing wrong with a wire rope on a winch, I will not say its common place but I have seen it quite often. Classification Societies have no issue (that I am aware of) and approve the use. Wire rope, like rigging needs different levels of attention, I suspect, but if the wire rope is checked, especially the swage - I don't see an issue. It can be as strong as chain and that's the issue the Classification Socitities seem to worry about.

The reason I did not progress it with 4mm chain - I was not sure that the 4mm chain would fit/work on a drum winch, wire is proven - no-one as far as I know (and I did check) uses small chain on a drum winch - one reason being that chain is heavier than wire and there were question as to whether the engineering would be man enough (on a device small enough to fit on a yacht). There was a query raised on the sheer weight of 4mm chain and the centrifugal force, compared to wire. None of the wire winch makers seemed keen on the idea and certainly none put their hands up and said - we'll give it a whirl.

As I mentioned HT 4mm chain is available from a primary, reputable European chain maker, It is not galvanised, but I can overcome that issue, and when galvanised it would have the same strength as 8mm G40. There is an issue of components, shackles, chain hooks etc - but there are options. Basically it was not entirely straight forward and I was discouraged - sticking with 6mm was simpler. For 6mm: Windlass and gypsy available off the shelf, components off the shelf available, many manufacturers of 6mm chain upto G120 strength - I took the easy option (now followed by a number of owners).

But if you use 6mm (or 4mm) you do accept using a snubber (or bridle). By decent I mean 'measurable elasticity' (made from nylon and 3 ply, or kermantle with around 40% elasticity and well over (2 times) deck length).

Jonathan