Snubber/bridle revisted

[jfm]

Isn't that defeating the whole point of taking load off the windlass? Having said that with stretchy nylon, there will be less shock involved.

It's only the gears you want to unload. The capstan being pulled sideways by a rope loop placed over it is perfectly ok

 

[Magnum]

Job done?

So what to cover the loop with, if anything?

Nylon is generally recommended for snubbers due to its stretch, but conversely it isn't very UV or salt water resistant!

 

[Hurricane]

Job done?

So what to cover the loop with, if anything?

Nylon is generally recommended for snubbers due to its stretch, but conversely it isn't very UV or salt water resistant!

I assume you would make it from one piece if rope.
You will need the actual loop loose enough to slip when the capstan rotates.
I think I would make it from three strand with a simple spliced soft eye (about 250mm dia) to loop over the capstan.
You could make it streatch by adding one of those "in line" rubber snubbers but IMO that would just make it too complicated.
JFM makes it sound so easy - just clip it on and loop it over the capstan.
I seem to remember that on your new boat, the chain runs over the bow rather than through a hawser pipe like on the old 67.

If that is the case, it should be much easier to deploy.
You should be able to attach the chain hook and hold it tight with one hand whilst pressing the windlass button with the other hand.
On the old 67, we have to lean over the bow and reach down to where the chain comes out of the hawser pipe.

So, in fact, you might end up with a very simple and easy to use solution.

 

[jfm]

Job done?

So what to cover the loop with, if anything?

Nylon is generally recommended for snubbers due to its stretch, but conversely it isn't very UV or salt water resistant!

Yep job done. The loop will only contact 200 degrees of the capstan, not 360 degrees as indicated in your pic. That will ensure the rope loop slips on the capstan, as you motor the gypsy to deploy/undeploy the snubber. As you know, no capstan will haul in a rope unless there is ~ 360 degrees of taut contact, and usually you give it 720 degrees

 

[Magnum]

Yep job done. The loop will only contact 200 degrees of the capstan, not 360 degrees as indicated in your pic. That will ensure the rope loop slips on the capstan, as you motor the gypsy to deploy/undeploy the snubber. As you know, no capstan will haul in a rope unless there is ~ 360 degrees of taut contact, and usually you give it 720 degrees

Excellent. Thanks for the suggestion jfm.

I was thinking of using Marlow Multiplait Nylon - https://www.marlowropes.com/product/multiplait-nylon

Unsure about diameter though as it needs to be strong but also stretch. Maybe 20mm?

 

[jfm]

Excellent. Thanks for the suggestion jfm.

I was thinking of using Marlow Multiplait Nylon - https://www.marlowropes.com/product/multiplait-nylon

Unsure about diameter though as it needs to be strong but also stretch. Maybe 20mm?

i agree that 20mm dia sort of feels right but I gotta say there is a lot of carp talked about shock absorption in yachtie bars.

Nylon rope stretches about 25% at breaking load, which is 8 tonnes from the table you linked to. You will be getting the hell out of an anchorage when you see one tonne. The relationship is linear so 1 tonne is 3% stretch i.e. 9mm total elongation if you make your strop 3m long. 9mm, ffs. That's totally pointless and the chain catenary effect and bow droop are far far better for shock absorption in leisure anchoring. Hence my carp comment.

Now you could use 10mm rope which breaks at about 2 tonnes. That would be usefully stretched 12% at one tonne, i.e. 36cm on a 3m piece. BUT that is a heck of a lot of stored energy, and if something sudden happens and it snaps at the chain end with a child nearby you'll be googling nearest casualty ward. So you need a big safety factor, like your 20mm sensible proposal, but catch 22 that's never gonna stretch in normal leisure anchoring.

There you have it. And why I never bother and never will!

 

[Magnum]

So I take it you are not keen on the idea?

OK point taken. So let's increase the length to a more yachtie like 4m and use 16mm multiplait. At 1 tonne that's approx 20% of its min breaking load so let's say 5% stretch. That's 20cm of stretch which just might reduce snatch a bit, and don't forget we have taken load off the winch gears and stopped any stem head chain noise.

Worth it for a couple of hundred quid? I'd say so.

 

[Magnum]

i agree that 20mm dia sort of feels right but I gotta say there is a lot of carp talked about shock absorption in yachtie bars.

Nylon rope stretches about 25% at breaking load, which is 8 tonnes from the table you linked to. You will be getting the hell out of an anchorage when you see one tonne. The relationship is linear so 1 tonne is 3% stretch i.e. 9mm total elongation if you make your strop 3m long. 9mm, ffs. That's totally pointless and the chain catenary effect and bow droop are far far better for shock absorption in leisure anchoring. Hence my carp comment.

Now you could use 10mm rope which breaks at about 2 tonnes. That would be usefully stretched 12% at one tonne, i.e. 36cm on a 3m piece. BUT that is a heck of a lot of stored energy, and if something sudden happens and it snaps at the chain end with a child nearby you'll be googling nearest casualty ward. So you need a big safety factor, like your 20mm sensible proposal, but catch 22 that's never gonna stretch in normal leisure anchoring.

There you have it. And why I never bother and never will!

Btw, it's 9cm not 9mm stretch in your example.

 

[Portofino]

Use one of those black elastic mooring line snubbers of a suitable size to add more elasticity .

I, am not convinced about the " saving the gears " argument ?
Would have thought the force is on a thrust bearing or shaft stub .
Gear wear only occurs when recovering , motors turning - pulling ?
Static - I suspect gears are under a none damaging wear force .

Just think about when the anchor is up - ifs it's "bar "tight like 90% of ave Mobo ,S - then if you are correct -gears take static load ( not to be confused with dynamic )- then windlass,s would be consumable / throw away products due to duff gears .
They aren't.
More likely to burn motor or need new bushes in that .

Sure the gears will ultimately wear - depending on useage , but I don t think a anchor snubbers is going to extend the gear life .

Just arguably if long enough add more catenary spring , take a little anchor dragging shock load off - if want to stay ?
And as you say decease the noise / rattle / grinding @ the roller end .

I think if the windlass is carefully matched along with the rest of the ground tacke - it won't need any protection .

 

[jrudge]

What problem is all this actually seeking to solve?

Putting additional bits on the anchor simply makes it harder to deploy and harder to recover ( which is usually done by your partner / mate with you are the helm) so requires more briefing and more to go wrong.

But I still don't understand the problem.

You just flip on the chain stopper and job done surely. As you bring in the chain it releases by itself so no trauma, lines and so on.

I have had the winch slip a few times on windy day ( it is quite possible that the clutch needed another few mm of tightening up) ... but that is what the chain stopper is for.

I can possibly see that it could be less noisy in the front cabin, but this would be similar to when you deployed a looped rope when on a bouy for the night ... and that can be noisy as well as the rope holds against the hull and then suddenly moves a few CM with the associated noise that comes with it.

Any if some some reason you need to up anchor in the middle of the night as you are dragging, or the wind comes up and you want to let out some more chain this has suddenly become far more complicated. Even in normal use you have to remember to remove it and the chain stopper does this by itself and just releases as you winch in.

I may have missed the point so feel free to correct my thinking !

J

 

[Magnum]

jrudge, I don't have a chain stopper and fitting one seems to be more involved (and costly) than expected (details in another thread).

 

[Nick_H]

M, I made up a snubber to operate in the way you're thinking, with an eye to loop over the windlass drum, some rubber shock absorbers, and a 10mm chain hook. It didn't work that well. The main issue is that when the boat yaws in strong wind, the rope rubs on the inside edge of the stemhead, and as it stretches and returns it starts to wear/cut the rope. It also tends to pick up the loose chain as it moves from one side to the other and grinds it against the inside of the stemhead, so you don't get away from the noise, or the lateral force trying to bend or loosen the stem fitting. I went back to a twin line set up, one to each bow cleat.

 

[Magnum]

Thanks Nick. Is chafe on the hull rubbing strake an issue using twin lines?

 

[jfm]

Btw, it's 9cm not 9mm stretch in your example.

Yep sorry my mistake, d'oh. That said my 1 tonne was a gross overestimate of what you'll see in leisure anchoring unless you like harsh conditions so you might see 9mm more often than 9cm

 

[Zing]

I'm not too happy with some of the advice in this thread.

I am mainly a sailboat driver and I spend a LOT of time anchored overnight. I realise it is very different from a lot of Med power boating. Still, there are a lot of overlaps and I hope you don't respond to the suggestion that you should dismiss my input as being from a low-life raggie. My boat has similar requirements to the boats here, being of comparable displacement and windage to the larger ones (40 ton). I have similar equipment. I use a 12mm grade 40 chain and a 20mm dia nylon octoplait snubber to a 75kg Rocna.

I anchor using 9m of the 20mm snubber line attached to my two bow cleats, similar to the way you sketched, but with much reduced angles as my cleats are much further aft. The advice on angles is correct. The angle from a line drawn from the cleat, parallel to the anchor chain going to the bridle leg needs ideally to be less than 60 degrees to ensure that leg isn't unequally loaded. Or you have to beef it up and with the really high angles in the original sketch, probably the cleat too. The Mk II sketch looks good if you can deal with chafe. A long snubber will also help a little with that.

It was suggested you don't need to worry about bad conditions when anchoring as if they occur you just lift anchor and go. I think this is wrong. You have to go before it gets bad and except for sustained weather systems you don't usually know in advance. When a squall comes through it can go without warning very quickly to 40 to 50kt of wind with horizontal rain and zero visibility. It seems to happen at night too, so you can't see it coming, if for no other reason that you are asleep. It is not the time to be messing around trying to lift an anchor and then motoring out between the crowd of anchored boats you can't see in the pitch dark and driving rain. Moving at that time is more dangerous than staying put, unless of course you are dragging very badly.

Likewise I don't think it is a good idea to put your snubber on the capstain. One of the main functions of a snubber is to ensure your windlass doesn't get the anchoring loads. This is doing the opposite. Check your windlass manual. The use of a snubber and or chain stopper will certainly be required. The capstain is also imparting off centre loads, so it is even worse if you load that up. The windlass is usually not mounted any where near as robustly as the cleats. Certainly so in my boat. You should secure the anchor somewhere else.

Don't rely on the clutch to relieve the load. It's not there for that reason. It's there for deploying chain quickly. You don't want it to slip as that means your chain will slip out. Can you be sure it will slip just a tiny bit? It's not easy to set accurately. I wouldn't rely on doing that, it could go wrong badly. You want your chain to stay in the boat, not on the seabed.

As to the question of how effective a snubber is. Here's an example, given a rise from 500 to 1000kg force on a 12mm chain with 50m deployed and attached to 9m of 20mm octoplait nylon, such being a scenario you will see in strong, but not extreme winds. You will have about 8mm extra movement from the catenary, an extra 2mm stretch from the chain itself and 135mm from the snubber. The deceleration and absorption of shock loads is proportional to that movement, so clearly the snubber is very much the best solution.

Catenary only really is significant with low loads, and with the lowest of loads it is the biggest factor by far, with the highest loads, it is the smallest factor, such as to disappear from influence almost totally at the extreme. Clearly you are concerned with high loads scenarios only as that is when problems occur.

 

[jrudge]

jrudge, I don't have a chain stopper and fitting one seems to be more involved (and costly) than expected (details in another thread).

OK - that makes sense.

The chain stopper was fitted on the boat from new - it is I assume cheap but maybe difficult to fit given the need to secure it .

 

[MapisM]

in Mk2 neither the snubber lines nor the chain can rub/pull the bow roller cheecks, possibly making some grinding noise.

M, I made up a snubber to operate in the way you're thinking, with an eye to loop over the windlass drum, some rubber shock absorbers, and a 10mm chain hook. It didn't work that well. The main issue is that when the boat yaws in strong wind, the rope rubs on the inside edge of the stemhead, and as it stretches and returns it starts to wear/cut the rope. It also tends to pick up the loose chain as it moves from one side to the other and grinds it against the inside of the stemhead, so you don't get away from the noise, or the lateral force trying to bend or loosen the stem fitting. I went back to a twin line set up, one to each bow cleat.

Thanks Nick.

LMAO, now that's a "full Lakesailor" as per TCM rule 5a, if I've ever seen one...

 

[MapisM]

It was suggested you don't need to worry about bad conditions when anchoring as if they occur you just lift anchor and go. I think this is wrong. You have to go before it gets bad and except for sustained weather systems you don't usually know in advance. When a squall comes through it can go without warning very quickly to 40 to 50kt of wind with horizontal rain and zero visibility.

Mmm... I have a funny feeling that you are talking of cruising grounds rather different from the ones most of us are used too.
I very much like Antarctica landscapes, but I'd rather choose a nuclear powered icebreaker than a pleasure boat, to cruise down there...

 

[Magnum]

Check your windlass manual.

From the Lewmar V6 manual - http://www.lewmar.com/sites/default/files/Manual_V1-6_65001201 issue4a-english.pdf

‣ Windlasses must not be used as the sole means of securing the anchor to the bow fitting especially under
storm conditions. Anchors should be independently secured to prevent accidental release.

‣ A windlass should never be used as a mooring bollard, the anchor rode MUST be secured to a mooring cleat,
chain stopper or other designated strong point. Using the windlass to secure the rode will damage the
windlass.

 

[Portofino]

From the Lewmar V6 manual - http://www.lewmar.com/sites/default/files/Manual_V1-6_65001201 issue4a-english.pdf

Ask Princess - for guidance on following those instructions
Without a chain stopper.
Go from there ?

Thank them for the fenders and mooring lines etc