Do you use an anchor snubber?

[RichardS]

Richard, the gypsy should be holding the chain better than you describe.

Richard,

I'd agree your gypsy should retain the chain.

We'll have to agree to disagree, I'm afraid. My chain is correct for my gypsy and has never slipped once in normal usage, and that's with a 25kg anchor and 100m of 10mm chain fully out. I simply do not believe that a gypsy with a 90 degree contact run is expected to hold the windage of a cat in wind and waves above 25 knots and that the snatch load on the chain will inevitably jump a link or two around the gypsy, as Grahame finds above.

Richard

 

[NormanS]

We'll have to agree to disagree, I'm afraid. My chain is correct for my gypsy and has never slipped once in normal usage, and that's with a 25kg anchor and 100m of 10mm chain fully out. I simply do not believe that a gypsy with a 90 degree contact run is expected to hold the windage of a cat in wind and waves above 25 knots and that the snatch load on the chain will inevitably jump a link or two around the gypsy, as Grahame finds above.

Richard

It may depend on the vertical load of the chain hanging down in the chain locker. I asked previously if your chain locker was particularly shallow. Or is your windlass down in the chain locker? In any event, if my chain showed any tendency to ride over the gypsy, I would be concerned enough to do something about it. A possible solution has already been mentioned - another roller that the chain would pass under, in front of the gypsy. Other solutions are possible.

 

[Neeves]

We'll have to agree to disagree, I'm afraid. My chain is correct for my gypsy and has never slipped once in normal usage, and that's with a 25kg anchor and 100m of 10mm chain fully out. I simply do not believe that a gypsy with a 90 degree contact run is expected to hold the windage of a cat in wind and waves above 25 knots and that the snatch load on the chain will inevitably jump a link or two around the gypsy, as Grahame finds above.

Richard

You should not have e snatch loads either. That's exactly the reason people use an elastic snubber(s). An inelastic bridle, inelastic because the raw material for the rope has minimal (or insufficient) elasticity or the rope is simply too big (too large a diameter) - and worse both of these characteristics - then you will enjoy snatch loads. Change to an elastic bridle, there are many ways to do this, and you will have no snatch loads. The snatch loads you feel on your cat are the same snatch loads your anchor feels ( except it expects you to reduce those snatch loads to give it (the anchor) as a good a chance as possible).

If you have nylon mooring lines, 12mm would be about right, I'd rig up a temporary bridle, 10m each arm, and try it - I think you will find the snatch loads disappear. Your wife will think you a magician as she can then serve the chilled chardonnay in those decent Dartington glass glasses, as the other cats owners do, without fear of them smashing every time you have a snatch load.

Jonathan

 

[Neeves]

What is extraordinary is the fact you suffer snatch loads, at a modest 25kn, but deploy 10mm chain (and have plenty in the locker). Our cat is a bit smaller than yours and we use 6mm chain (with a decent bridle). You sail a 40' and bigger 'all over' (bigger than the 2' difference in length). We don't have snatch loads, at all. The argument against smaller chain is that larger chain offers the 'magic' of catenary - you appear to contradict the mantra

and

You are an excellent advertisement for down sizing chain.

Why carry 100m of 10mm chain weighing a cool 230kg when you can carry 80kg of (high tensile) 6mm chain (with snubbers you can claim for free (if you re-cycle). Your chain needs a more expensive windlass, more power, takes up oodles of room - and apparently allows snatch loads at 25 knots. Worse you cannot drink wine from 'real' glasses nor eat dinner from bone china.

Light chain rules!

Jonathan

 

[RichardS]

I'm not going to quote anyone because that just further stimulates discussion and there is no point doing that once I have agreed that we disagree, excepting Grahame.

However, I will recap that the 25kg anchor and 100m of 10mm chain works perfectly well when fully extended and in normal use and therefore there is no issue or problem to be addressed. I will also recap that I am only referring to a situation where there is no snubber attached and no chain lock engaged.

Richard

 

[Kukri]

A snubber question.

On a boat displacing 20,000 lbs in cruising trim I used a length of 8mm three strand nylon. The breaking load is given in some places as 2,295 lbs or 10.2 kilonewtons.

On a boat displacing 48,000 lbs, what should I use?

10 mm diameter, 3,240 lbs / 14.4Kn or 12 mm diameter, 5670 lbs / 25.2 Kn

12mm seems absurdly heavy.

 

[LadyInBed]

Here is a thought, given the same diameter gypsy, using 6mm chain the gypsy will have more links in contact over the 90° than the setup with 10mm rig.
Hence 10mm more likely to jump than 6mm.

 

[Frank Holden]

A snubber question.

On a boat displacing 20,000 lbs in cruising trim I used a length of 8mm three strand nylon. The breaking load is given in some places as 2,295 lbs or 10.2 kilonewtons.

On a boat displacing 48,000 lbs, what should I use?

10 mm diameter, 3,240 lbs / 14.4Kn or 12 mm diameter, 5670 lbs / 25.2 Kn

12mm seems absurdly heavy.

I have a 3 or 4 metre length of 3 strand nylon... 12mm.... with a chainhook in the end. Normally deploy 2 metres and turn up on cleat... Seems to work.

Lunch stop ? Same kit I just put the hook on just before/inboard of the roller.. simply to take any load off the capstan.

 

[lw395]

A snubber question.

On a boat displacing 20,000 lbs in cruising trim I used a length of 8mm three strand nylon. The breaking load is given in some places as 2,295 lbs or 10.2 kilonewtons.

On a boat displacing 48,000 lbs, what should I use?

10 mm diameter, 3,240 lbs / 14.4Kn or 12 mm diameter, 5670 lbs / 25.2 Kn

12mm seems absurdly heavy.

That's because 48,000 lb is absurdly heavy.

12mm for a 24T yacht? Most things other than the flag halliard will be fatter than that?

 

[Neeves]

I have a 3 or 4 metre length of 3 strand nylon... 12mm.... with a chainhook in the end. Normally deploy 2 metres and turn up on cleat... Seems to work.

Lunch stop ? Same kit I just put the hook on just before/inboard of the roller.. simply to take any load off the capstan.

You are just using the strop to take the load off the windlass and maybe stop the chain rattling - it will have no snubbing effect. Why bother - just use a chain lock - you will get the same result.

The yacht is sufficiently heavy it may not yaw nor hobby horse - you might be able to rely simply on catenary - you will not know until you try it. When you find out - let us know, I, for one, am interested.

If you want to snub you need something of boat length (and I'd go and get 2 old pieces of climbing rope from a rock climbing gym - use one and keep the other as back up - they do fail.

Jonathan

Sorry this was meant to link to Kukri not Frank

 

[Neeves]

As an aside

We use 12mm dynamic climbing rope, kermantle construction, - it does not seem overly large.

I'm having some 14mm sent to me for test, 45kN breaking strength. It has, or it is said to have, the same elasticity characteristics as 12mm (or 10mm) kermantle - just its stronger.

Evan Starzinger used 12mm climbing rope, as a snubber, on Hawk - as I say 12mm is not out of the ordinary (for snubbers) and would look like a toy (or the flag halyard) on Kukri .

The big issue with kermantle construction is that you cannot splice it (though I did hear of someone here who thought he had found a way). Commonly eyes are sewn into the ends, by the rope maker ( and presumably by a decent sailmaker).

If the 14mm cuts the mustard it, 60m of it, will be used (half each side) on a 50' cat, currently due to be launched March 2020.

Jonathan

 

[Graham376]

As an aside

We use 12mm dynamic climbing rope, kermantle construction, - it does not seem overly large.

Many years ago, I bought some pale cream matt finish 12mm 3 strand nylon which I use as a snubber. Much stretchier than the normal shiny stuff but haven't seen it on sale again.

 

[Zing]

A snubber question.

On a boat displacing 20,000 lbs in cruising trim I used a length of 8mm three strand nylon. The breaking load is given in some places as 2,295 lbs or 10.2 kilonewtons.

On a boat displacing 48,000 lbs, what should I use?

10 mm diameter, 3,240 lbs / 14.4Kn or 12 mm diameter, 5670 lbs / 25.2 Kn

12mm seems absurdly heavy.

A snubber needs to be stretchy, but too stretchy and it will overheat and fail or it will get fatigue failure and have a short life, so you want a snubber generously sized for the boat and conditions you are expecting. To get more stretch, but still retain a low stretch to max stretch ratio you can simply extend the length of the snubber. Nylon will stretch about 30% at max load and you want to be sized to operate below 15% of max to have a long life snubber. If you have a swingy boat at anchor and big wave loads the loads can vary by a factor of 2 to 3 or higher compared to the average. Relatively higher peak loads can be bad with short waves if you are lightweight with low inertia like a catamaran, but worse with a heavy boat and bigger waves. So there's no universal answer.

I size my snubber to be the same breaking strength as my chain (heavy monohull). I work with about 8m of snubber length, which gives me about half a meter of stretch in 40kts. I use multiplait nylon, which gives more stretch than 3 ply for a given rope strength. I find it works well. For your boats I'd guess 14mm or 16mm multiplait and 18mm multiplait were suitable. I know you gave weight, but I'm assuming they are 40 and 50ft monohulls as it is windage mainly that loads the anchor up.

It's really trial and error, but here's an article to estimate loads involved:
https://www.practical-sailor.com/issues/30_17/features/5005-1.html?zkPrintable=true

Here's info on stretch:

 

[Kukri]

A snubber needs to be stretchy, but too stretchy and it will overheat and fail or it will get fatigue failure and have a short life, so you want a snubber generously sized for the boat and conditions you are expecting. To get more stretch, but still retain a low stretch to max stretch ratio you can simply extend the length of the snubber. Nylon will stretch about 30% at max load and you want to be sized to operate below 15% of max to have a long life snubber. If you have a swingy boat at anchor and big wave loads the loads can vary by a factor of 2 to 3 or higher compared to the average. Relatively higher peak loads can be bad with short waves if you are lightweight with low inertia like a catamaran, but worse with a heavy boat and bigger waves. So there's no universal answer.

I size my snubber to be the same breaking strength as my chain (heavy monohull). I work with about 8m of snubber length, which gives me about half a meter of stretch in 40kts. I use multiplait nylon, which gives more stretch than 3 ply for a given rope strength. I find it works well. For your boats I'd guess 14mm or 16mm multiplait and 18mm multiplait were suitable. I know you gave weight, but I'm assuming they are 40 and 50ft monohulls as it is windage mainly that loads the anchor up.

It's really trial and error, but here's an article to estimate loads involved:
https://www.practical-sailor.com/issues/30_17/features/5005-1.html?zkPrintable=true

Here's info on stretch:

Thank you. Just what I was looking for. Low windage 55ft monohull cutter.

 

[Saguday]

Good thread, interesting. We usually use a snubber but not for quick lunch stops. We use a bridle with a chain hook, it’s longish about 5m each arm which we usually tie off on the bow cleats and then let off a metre or two of chain to hang loose. Chain is held by a very beefy chain stop so no load on windlass or cleats. Our boat is a heavy-ish beamy long-Keeler and although she doesn’t shear around wildly like many the cutter rig does contribute to some swinging. We’ve found the bridle snubber settles things down and certainly removes anchor chain noise.

However, I’m currently rethinking our snubber. I’ve had two concerns:

- it’s not long enough and probably doesn’t provide enough stretch, so I was going to lengthen it to either the mid cleats or stern. I prefer the bridle to a single line, though, because I think it damps down swinging. I’m not sure how I can make a bridle work from stern cleats though.

- I want to change the chain hook. We have a Wichard SS hook with a spring pin hook bought early in our cruising career and although we’ve never had a problem with it I’m concerned it might bend and lock to the chain under duress - even before I read the comments here. I’ve looked at all sorts of alternatives but not decided yet - a simple very solid basic hook, ungated, is my favourite at the moment.

A single line to the stern is quite popular amongst fellow IP owners with many not using a hook at all, just a rolling hitch to attach the snubber line onto the chain. We’ve not tried it yet and noticed that this option has not been mentioned so far on this thread (unless I missed it). Cheap and simple to try out though.

 

[Kukri]

I used to use a rolling hitch but I found that in nylon rope even a rolling hitch can be tricky to undo after it has been under serious tension. At the moment I am using the Wichard one, which I had bought before Neeves warned me off them. Being used to ships where the mooring warp snap back zones are painted on the deck I’m not very keen on running snubbers along the deck to an aft cleat. I’d rather have more of it in the water.

 

[Big Andy]

My setup as it's used at present. It used to run from the stern cleat but due to chafe damage I had to trim it back a couple of feet and it's a little short now. I think this works a little better as it's no longer running along the side deck and it's freed up a couple of blocks it used to run through. I do intend to put some nice stainless strips at the edge of the deck to stop further chafe there and protect the boat itself.

...........

 

[LadyInBed]

I want to change the chain hook. We have a Wichard SS hook with a spring pin hook bought early in our cruising career and although we’ve never had a problem with it I’m concerned it might bend and lock to the chain under duress - even before I read the comments here. I’ve looked at all sorts of alternatives but not decided yet - a simple very solid basic hook, ungated, is my favourite at the moment.

Why don't you just take the pin out?

 

[Saguday]

Why don't you just take the pin out?

Could do, not looked at it much but why not?

 

[Neeves]

We have had 2 bridles fail, in 20 years. Both were 3 strand. On both occasions they failed when we were well away from the snubbers and I simply don't know how much recoil there was - but Kukri's comments on the dangers are valid (on large ships - men have been killed - and for this reason, I believe the US Navy banned the use of nylon (for mooring warps) - but this might be anecdotal. When our bridle, single arm, failed - it was like a gunshot.

In both of our cases the failure occurred where the bridle arms can rub on the bobstays that hold up, or down, our bowsprit. The snubbers, each arm of the bridle, do not noticeably abrade as when under load they actually do not touch the bobstays - but they do rub in light winds.

The trouble with 3 ply is you can wear each, or all, strands and even though you see no product of abrasion the filaments are obviously damaged, for each of the 3 strands. We moved to braided line and then Kermantle - with the hope that the internal filaments would be slightly better protected and that the outer braid would show signs of failure first.

We are now using kermantle - but have possibly not been using it long enough (maybe 5 years) - we have no signs of abrasion and have had no failures. However within our usage period of Kermantle we have retired our first bridle, of 15m each arm, and moved to 30m each arm.

If you run the snubbers through the stanchion bases, or though the devices, attached to stanchions, used to tidy furling lines then if there is a failure the lines are contained, or retained and whiplash minimised.

An advantage of running to the transom is that you can vary snubber length from the cockpit - so there is no need to be on the bow when you need to extend your snubber. You do need to manage the lazy loop, of chain, to allow you to extend the snubbers without need to extend the chain deployed (as in many cases this would only be possible with a trek to the bow - and the weather is likely to be grotty when you want to extend).

Jonathan