Anchor snubber- long stretchy rope or rely on catenary

phanakapan

phanakapan

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I’ve heard conflicting arguments about the use and effectiveness of anchor chain snubbers. One argument says, of course use a rope snubber (either bridle or straight) to stop direct snatch on your windlass- but that the rope can be strong and (fairly) short because the catenary of the (suitably long length) of chain provides far more ‘stretch’ than a few metres of 3 strand. The other argument says use the longest amount of stretchy rope that you can. Of course either way one needs to attach the warp to the chain correctly, avoid chafe etc. Your thoughts?
 
phanakapan said:
I’ve heard conflicting arguments about the use and effectiveness of anchor chain snubbers. One argument says, of course use a rope snubber (either bridle or straight) to stop direct snatch on your windlass- but that the rope can be strong and (fairly) short because the catenary of the (suitably long length) of chain provides far more ‘stretch’ than a few metres of 3 strand. The other argument says use the longest amount of stretchy rope that you can. Of course either way one needs to attach the warp to the chain correctly, avoid chafe etc. Your thoughts?
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There is effectively no stretch in the chain, as a surprisingly small load gets it surprisingly straight. If you need a bit of spring, nylon rope is the way to go. If you give details of your boat, someone will probably be able to recommend a size and length.
 
phanakapan said:
I’ve heard conflicting arguments about the use and effectiveness of anchor chain snubbers. One argument says, of course use a rope snubber (either bridle or straight) to stop direct snatch on your windlass- but that the rope can be strong and (fairly) short because the catenary of the (suitably long length) of chain provides far more ‘stretch’ than a few metres of 3 strand. The other argument says use the longest amount of stretchy rope that you can. Of course either way one needs to attach the warp to the chain correctly, avoid chafe etc. Your thoughts?
Click to expand...
I use a short length of strong rope; works for me

I'd never, ever have a chain just attached to a winch, put some form of locking between the windlass and the anchor.
 
If you have a chain lock, as we do, then load on the windlass is not an issue. Without a lock then relieving the load on the gypsy/windlass is the most important function of a snubber. However, even with a chain lock, a monohull often needs a snubber to prevent gelcoat damage and we have a snubber on the cat for the same reason to a small extent, although mainly to distribute the load between the two hulls and hold the boat steadily into the wind/swell.

The snubber presumably provides some "stretch" but that's more a useful by-product rather than the primary function.

Richard
 
I always use a snubber. 44 ft boat 7/8 three strand nylon rope. About 6 ft effective in daily use with another 20 ft in reserve for wild conditions. This has been used just twice in 15 years of living on the hook.

As Ladyinbed says it makes for a MUCH quieter boat at anchor. No rumbling chain sounds.
 
I have anchored on many an occasion, sometimes for weeks at a time, in many different sorts of seabed, often in very difficult wind and tide conditions. I know only too well the reasons for using a snubber in the first place..... I’m currently making a new snubber (to fit my 10mm chain, (60m plus extra rode available, 20kg Rocna, 36’ boat) and was trying to decide how long to make it and out of what sort of rope- and whether to make it a 2 legged bridle or single line. Previously I used just enough 3 strand so the chain hook mostly sat just out of the water; it always worked fine, I always use enough chain so that the curve never completely straightens. But I’ve read a lot of articles that advise using much longer lengths of rope ‘for the stretch’. Hence my question.
 
Catenary works well in sufficiently deep water, with adequately sized chain, but has little effect in shallow water, where there is some benefit in having a stretchy snubber. If we have anyone in the forward cabin, I'll rig a short snubber to prevent chain noise, but normally just use a chain stopper.
 
I have just bought a chain claw grip and a rubber snubber.

I will make up a nylon rope shock absorber enhanced by the snubber. I expect the rope will be about 20-25'long but I will see how it feels when I'm back on the boat.
 
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If you commence your snubber at the transom, attach to the horn cleat, and run up the side decks (inside the stanchion bases as you do your furling lines?) then you can have a deck length snubber and only a short section forward of the bow. You need to watch for chafe, obviously, and that is most critical when you run the snubber out board, fairleads? If you have a beamy yacht then a bridle works well and helps steady the boat, stops (or reduces) it veering. If you have a narrow beam its impossible to get a wide enough 'V' to have much effect.

Having a cat we use a bridle but also use a short snubber (at the same time). Snubbers fail, if they do not fail or need replacement, then they are not sufficiently stretchy. When they fail (noise like gunshot) you 'fall back' on the chain (and windlass). So we use a short snubber 0.5m to protect the windlass - you could use a chain lock. We use the short snubber also when on passage - in case the cone slips and wants to deploy all the chain and anchor, most embarrassing (belt and braces).

At around 20 knots all your chain is off the seabed, at 30 knots it looks about straight (assuming normal scope and not overly deep water). From about 25 knots the snubber starts to earn its keep - and we would not be without it as there is no catenary left to absorb energy (the nylon will keep working till it breaks!) the catenary will stop working at about 30 knots - and between 25 and 30knots both the snubber and chain will work together.

You will find a boat length snubber makes life at anchor more comfortable for reasons mentioned by others. We use longer snubbers, 2 x bridle arms, 30m (11.5m cat) and add length if the winds increase beyond 30 knots.

Depends on your yacht size but 11mm dynamic (lead) climbing rope from climbing gyms makes a good snubber. We use 2 x 30m (as said). Starzinger used his own retired climbing rope on Hawk (I think was about 45' alloy). For a lighter yacht say smaller than 35'/40' I might use 8mm climbing rope, look on eBay for someone offloading their old rope(s). Gyms tend to be not very high but you can usually source 15m lengths, some walls are higher but there are less around and you need to search.

Jonathan
 
I use a full boat length snubber from a stern cleat. It stretches visibly as the boat moves. But I suspect that the warning rumbling sound of an anchor dragging - not a problem I experience with my chinese copy CQR - may well get muted.
 
Anchor alarms can still rumble, or give a piercing shriek - if you wired in a piezo electric alarm - if you use one (though they can reduce life expectancy for guests)

There is no shame in belt and braces.

Anchor alarm are a bit like insurance, life raft, EPIRBs and life jackets - you hope you never need one (or hear it) but you have them just the same

Jonathan
 
Indeed, I usually set my GPS alarm to 0.03nm having found that 0.02nm can cause interrupted sleep at tide changes but is fine when the wind is up. With a depth alarm, anchor alarm, CO alarm, gas alarm, DSC alarm and sometimes even a mobile phone alarm, I almost expect to be woken.
 
awol said:
I use a full boat length snubber from a stern cleat. It stretches visibly as the boat moves. But I suspect that the warning rumbling sound of an anchor dragging - not a problem I experience with my chinese copy CQR - may well get muted.
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Similar system onboard waiting to get tried in anger, nylon from bow back to a block next to the cockpit then back to near the bow to a length of tough dyneema over the bow roller. Clean snubber with no jellyfish tentacles plus easy to change the snubber without having to pull any chain in.

Here's hoping :)
 
Our system, which we have tried in anger, is chain hook (too fiddly to use a soft shackle with 6mm chain), turning blocks on each bow (its a cat) down to clutch on, each, transom, turning block and then to sheet winch (normal headsail winch (which is obviously free when at anchor :) ). We then have another 15m stored in a bag, as one stores sheets. As the wind gets up, I need to release the back up snubber (that protects the windlass) then release more chain and appropriate amount of extra snubber, each side. We can retrieve any 'excess' snubber if the wind eases simply by winching in.

We did look at having storm snubbers - but that was simply too complex - and extra long snubbers, or the ability to deploy extra length, seems to work.

An advantage is that 'normally' we have deck length of snubber and only a short section ahead of the bow, so no chance it will ever reach the seabed. It might look daft to have 15m deployed ahead of the bow in stronger wind - but who cares and who is watching?

Jonathan
 
I've got lots of advice (especially from Jon) on this last winter when I decided our snubber was in need of improving. I've since tried some things, observed and learnt. Our "day to day" snubber is still a 20mm Nylon octoplait (40 ft monohull, 8mm high tensile chain, 25kg Rocna), which we always attach as soon as the scope is paid out, before we set the anchor. It's effective length is about 4-5m or so, and it can be seen to stretch significantly when we set the anchor in reverse.

We also have a longer, thinner snubber, also of Nylon octoplait, but only 12mm. This is a bridle, as we hoped to reduce the boat veering at anchor. It did not help with that at all (yesyes, a riding sail probably would and is on the todo list somewhere). So for a monohull the only benefit of a bridle is redundancy (only one leg is loaded at a time anyways). Because it is longer, we use this one if we for some reason have to ride out swell at anchor, which is rarely a good idea, and it's almost always better to leave and go somewhere else, so we've rarely used it.

Also, because it is more stretchy, it actually made the problem of the boat veering (sailing at anchor) worse rather than better, as the boat can "bust out" further before the bow is caught by the ground tackle and forced around. This is probably different for multihulls.

The stainless hook is always under water and that doesn't seem to cause any kind of problem (it'll hardly ever end up on the exact same chain link twice anyways). It's however less deep under water (with slack chain) than our draft, so it can't touch the ground and unhook itself. The longer snubber also has a modified hook with a retainer clip (another idea of Jon's).

For this winter, I'd like to combine our experiences so far into a new snubber made of 20mm Nylon octoplait, which will be long enough to be routed through the centre in a foredeck cleat and cleated on a midships cleat, so it can stretch over a greater distance (without messing around with turning blocks for a snubber). This will also relieve any strain from the bow roller and move it on the very strong mooring cleats, although at a very slight angle.

But one remaining problem with going through the mooring cleats instead of the bow roller on our boat is that the chain is held further aft, which means in totally calm conditions it can touch the bow, make lots of noise and even lightly scratch the Coppercoat. So we mostly feed it over the bow roller, except when it gets rougher.

Retired climbing rope seems to be not a thing unless maybe you happen to be a climber or cruise/supply in local waters. I just don't see myself looking up the local climbing hall in a foreign country where I speak only a few words of the language, taking the dinghy ashore, parking it somewhere (quite difficult here in Italy anyways) and then using local transport to track down the climbing hall, wander in and try to explain with the help of Google translate that I would like some used rope of a very specific sort for free. Results would be highly doubtful :)
 
We have found a big difference on our last 2 boats with having a snubber such that we always use one now. I used to only put one on when we felt the conditions would be bad but I had to get out in the middle of the night too often and so it is always used. The old boat had a samson post so the anchor shain was tied off here and a snubber attached. The new boat has an electic windlass with no chain stop so the subber acts as this also. It is three strand nylon and is the length of the boat plus a bit. We use a portion for normal use and the whole run if conditions are poor. It stops the noise and veering and a significant amount of the surging. A chain hook seems to work but the old boat was small and so the rope for the subber fitted through a link. We also put one of those rubber dildos on it. The unit works well but I don't have any evidence that it is worse without the rubber thing it was simply a presumption that it would add some extra spring.
 
If using nylon rope for a snubber (polyester isn't stretchy enough) then I think a long length is necessary. Having just a metre or two seems a waste of time in that there's not enough stretch. I use 10m or nylon, with nearly 1 metre over the bow to the chain hook, then the rest along the deck to a cleat at the stern. The stretch at the bow can be 500mm at times (strong winds, bigger waves), and this part has plastic hose over the rope to lessen chafe.
I can't see how those rubber things have enough stretch to do the job.
 
I have 49 ft yacht, 40Kg Rocna. I always use a snubber as it takes the load off the windlass. In addition, it is possible for the anchor chain to pay out if the top nut on the windlass is not super tight! A snubber will prevent this happening

So hook onto chain. 3 strand polypropylene line up through bow roller. Plastic tubing to prevent chafe, Passes though a couple of snatch blocks to be made off on a mid-ships cleat. Then loosen the anchor to allow the snubber to take the strain.

TudorSailor
 
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