snubber chafe and melting

[rebel heart]

Curious if anyone here can talk about really bad chafe issues with three strand, including melting. I've only heard about reports from hurricane level conditions and the such. Up to around 30 knots I've not noticed any real problems with 1/2".

[Bash]

Originally Posted by rebel heart

Up to around 30 knots I've not noticed any real problems with 1/2".

Me either. But I keep a few 1/4" Dyneema whips handy in case I ever have to back up the nylon snubber.

[rebel heart]

Originally Posted by Bash

Me either. But I keep a few 1/4" Dyneema whips handy in case I ever have to back up the nylon snubber.

I've got the same with amsteel. Mainly I'm just wondering at what type of conditions I'd need to worry about that.

[Stumble]

We lost two boats in hurricane Katrina from the 1" storm lines melting right at the chocks where the line came onboard. So yes it is a problem. But as you mentioned I have never seen it from sub-hurricane conditions.

[s/v Jedi]

You notice the line is getting stiffer? Now you might think it's from UV damage, but just check the tail that is never tensioned: it has the same UV exposure but isn't as stiff. This is the result of internal chafing.

Internal chafing is not melting per se. It only ends in melting at the extreme end. It is the fibers chafing each other too, plus any dirt that gets into the rope makes it worse.

[Weyalan]

I thought the point of the snubber was to provide some stretch? Surely Dyneema or Amsteel is kinda inappropriate for such an application?

[s/v Jedi]

Originally Posted by Weyalan

I thought the point of the snubber was to provide some stretch? Surely Dyneema or Amsteel is kinda inappropriate for such an application?

They use that as a backup or chain-stopper I think. If you don't have that and the snubber breaks, the forces would be transferred to the windlass with possibly disastrous results.

[Weyalan]

Originally Posted by s/v Jedi

They use that as a backup or chain-stopper I think. If you don't have that and the snubber breaks, the forces would be transferred to the windlass with possibly disastrous results.

If the snubber breaks then it is most likely seeing some very big loads, Having a back up that doesn't have some way of mitigating those loads is likely only gonna end up breaking something else. Whatever you use in the role of snubber should, I think, have some stretch. Hell, double braid sheets, dock line, etc can all be pressed into snubber service. The only time I have been seriously worried about snubber loading I rigged a double loop of dock-line that would have taken over the load if the regular snubber broke (which it didn't).

[s/v Jedi]

Originally Posted by Weyalan

If the snubber breaks then it is most likely seeing some very big loads, Having a back up that doesn't have some way of mitigating those loads is likely only gonna end up breaking something else. Whatever you use in the role of snubber should, I think, have some stretch. Hell, double braid sheets, dock line, etc can all be pressed into snubber service. The only time I have been seriously worried about snubber loading I rigged a double loop of dock-line that would have taken over the load if the regular snubber broke (which it didn't).

Hello.. a backup means that a regular snubber is also in place and active.

[Weyalan]

The OP was asking about damage / chafe / melting of the snubber, so I guess talking about snubber breakage isn't that much of a stretch...

But I fully agree that in the event your snubber breaks you probably don't want the loads to be transferred directly to your windlass, so a "back up" of Amsteel will achieve that. But using Amsteel is not really backing up the shock-absorbing role of snubber, so you need to do something as a back-up for that too, otherwise there is a fair chance the shock loads are going to damage the hard point to which the Amsteel attached, no? .

[rebel heart]

From the lost of Moonduster. Moonduster lost - Cruising Anarchy - Sailing Anarchy Forums

It's worth pointing out as well that two of his snubbers popped. One from sheer load, and the other was sliced by the connection to the chain hook. It's a really interesting read.

Regardless of all that, in the future, I will shackle the bitter end of the chain around something extremely structural. In Moonduster, that could have been the forward end of the stainless steel I-beam that sat on the keelson and was the structural element that formed both the mast step and also accepted the keel bolt loads. Alternately it could have been shackled around the heel of the mast.

I continue to believe that had the chain been terminated with something other than rope that the outcome MAY have been different.

[rebel heart]

Another quote from Moonduster:

Ultimately, I've come to believe that snubbers are perhaps best viewed as a nicety in normal and moderately windy conditions but that for severe storms, one must expect that they will chafe/explode and that the rode's attachment to the yacht must stand on its own in the absence of a snubber. That attachement was the single point of failure that cost us the boat - although it's entirely possible that had the chain been better attached to the boat that we might have STILL lost the boat to a broken chain, broken shackle at the anchor, anchor dragging due to shock loading, etc, etc, etc. There were still 5-6 hours of very, very high winds to endure.

[DumnMad]

Informative quote Reb. Dyneema has its place as a snubber then. Only 3% elongation but low internal friction and heat build-up.

[Pelagic]

I have said before in other anchor threads that your ground tackle is only as good as your weakest link. So if your deck gear and windlass cannot hold the break out forces in storm conditions, you are simply depending on luck.

I would never recommend shackling the bitter end of an anchor to the boat.

The reason that the end is connected with a weak link is because sometimes you need to just let it all go very quickly and get out of a bad situation where you could lose the whole boat.

[Andrew Troup]

Originally Posted by Pelagic

I have said before in other anchor threads that your ground tackle is only as good as your weakest link. So if your deck gear and windlass cannot hold the break out forces in storm conditions, you are simply depending on luck.

I would never recommend shackling the bitter end of an anchor to the boat.

The reason that the end is connected with a weak link is because sometimes you need to just let it all go very quickly and get out of a bad situation where you could lose the whole boat.

I agree with that, and furthermore if you lose control of the chain running out (eg a key shears in the windlass, the brake lever connection fails, or ...) so that you end up with the chain striking sparks on the bow fitting as it runs out, with the hypnotic intensity of a williwaw ... then the severe shock when you reach the bitter end needs to be absorbed.

Particularly if you've got a "proper" sized anchor chain, rather than something which looks as though you've robbed a jeweler...