Construction Details for a Snubber

[Jim Cate]

G'DAy All,

There's been a lot of interesting commentary about size of chain and anchor recently on another thread, and of course the use of a snubber comes up repeatedly.
I think we all agree that the snubber is a key part of the system, especially in extreme conditions, and a little discussion of their design is in order.

My personal experience has lead to some questions.

First, while I recognize that three-strand nylon has perhaps the best stretch characteristics, I've found that when pulled hard it exerts some torque on the chainhook and thence the chain, and often winds the slack part of the chain up in knots during a blow. Can be a nuisance getting it back in then. So, I have gone to double braid nylon for snubbing. Less stretch (bad), no torque (good)... what do others think about this?

Second, chafe of the snubber is a problem when it is stretching back and forth through a fairlead or over the roller. I've considered making a strop of either very low stretch cordage (Dyneema?) or wire, with an eye/thimble/shackle connection to the proper snubber and a big eye to go over the sampson post. It would be long enough to reach beyond all chafe points. Anyone ever used a setup like this?

Finally, when anchoring in severe conditions I tend to use one long stretchy snubber plus a second much shorter one to keep the load off the windlass should the first one fail ( I don't have a chain stopper fitted). Anyone think this is a bad idea, or have a better suggestion?

All for now, so cheers

Jim and Ann s/v Insatiable II lying Broken Bay, NSW, Oz

[nitpik]

Mornin' Jim:
I don't see why braided nylon would be a problem for a snubber. Any stretch is better than no stretch, 'though I would be inclined to use a slightly smaller diameter line, and more of it. I have not found the twisting of 3-strand to be a big problem.
Your solution to the chafe problem sounds workable. I have a 9' bowsprit, which is wonderful to have, but it does complicate the entire anchoring process. One thing it simplifies is the chafe thing - I simply shackle my snubbing line onto the stem fitting, where the bobstay chain attaches, at the waterline. This completely avoids chafe, and it improves my scope, and it keeps the anchor chain from grinding on the bobstay chain, so I can sleep. (You have to imagine how THAT noise is transmitted through a steel hull!)
Not sure I like the complication of a second snubber for security. I place a steel pin through a chain link where it enters the hawse pipe, and this easily handles all shock loads. However, these solutions do not solve the problem of shock loads transferred to the windlass when the boat pitches up violently during anchor retrieval. (Your 2nd snubber, and my steel pin are removed at this point.) On my new installation, I will have a chain stopper, which will automatically take care of this situation. Also much safer!

[klem]

Anything with significant stretch should work. You can adjust the length of the snubber to get the stretch right. If the snubber is too long, it will act like a big spring and the boat will sail on the hook a lot. If the snubber is too short, there will be large shock loads. I have experienced the unlaying of 3 strand that is mentioned above and braid seems like it would be a good solution but I have no experience with it.

I definitely like the idea of a backup in case of chafe on the primary snubber. A second snubber would work or a chain brake would work until a new one could be rigged.

nitpik's snubber solution sounds good to me using the bobstay fitting. When I worked on a 92' schooner, there were nights that the sound of chain pulling against the bob chains was really disconcerting.

I know that some people use fancy rubber like snubbers and rave about them but I have never used one. I would also think that you could make a really nice one out of a yale mooring pendant, has anyone tried this?

[Jim Cate]

G'Day Klem and Nitpik,

Thanks for the thoughtful responses.

The 3-strand problems may be related to the specific ropes involved. There seem to be big differences in the lay and even the materials involved with different brands of rope. Here in Oz I have found it hard to get good quality 3-strand, and the double braid nylon is scarce... Maxwell in NZ are the only source that I've found, and it's bloody dear!

And the idea of attaching the snubber to the bobstay fitting is a good one . On our previous boat (Insatiable I) which was an old IOR one-tonner and lacking a bowsprit/bobstay, I fabricated and installed a hefty eye on the stem just above the w/l and did shackle the snubber to it. All the advantages that nitpik mentioned were there, but in the long run I abandonded it for day to day use. The difficulties were: only a fixed length snubber available, and I found that in different situations I wanted different lengths, and the requirement to winch in the chain far enough to un-hook the snubber if I wanted to veer out more chain. I did keep the eye for use in any severe anchoring situation (cyclone, etc) where I could re-attach a very long snubber in advance of the storm. Never had to do that, thankfully!

Haven't done that on I-two as of yet. I'm a bit reluctant to put a big hole in the timber stem on this boat... must remember to discuss this with the chap who built her!

Cheers for now

Jim

[s/v Jedi]

I wouldn't use double braid. If you really have trouble with 3-strand, choose 8 or 12-strand single braid nylon. These are used for dock lines.

Yes, a fitting low on the bow is optimal... it's also the strongest point of the hull. If you have a bow/anchor sprit you can put a strong cleat on that to hold the snubber and keep it free from anything that can chafe it.

No, a 2nd snubber isn't optimal, you really should get a big fat chain stopper. My maxwell chain stopper for 3/8" chain saved our boat during a hurricane.

Using spectra piece to prevent chafing: sure that works but why do that? Over the years we have found that the best chafing protection is none at all and consider the 3-strand snubber itself as the sacrificial part of the system. It's cheap than anything else and way less hassle.

cheers,
Nick.

[Albro359]

Yup I agree Nick...I have a little less than 300 ft of 3/8 3 starnd nylon as a spare rode...and I just keep making new snubbers...I mean you only need about 4 ft each time...and absolutely agree with the chain blocker between the windlass and the bow roller....never should the chain exert shock loads on the windlass...they will kill it.
Alan

[forsailbyowner]

I've ended up with an unconventional snubber over the years of trying different stuff. Currently I have a bridle built of 5/8" that is wormed parcelled and served for the 3' that are prone to chafe. They lead to a 1/2" swivel attached with thimbles and shackles. The stretchy part is attached the same way to the other end of shackle. I figure for extreme conditions I can add another line to the bridle over the rollers and to another cleat and another line to the shock absorber part. It would be longer than the 1st so it only comes into play when the 1st is stretched. The swivel setup with the bridal is also used when I set up a mooring with multiple anchors in areas where there isn't swing room for normal anchoring.

[James S]

We always used a snubber lead over the roller....but this thread has got me thinking...how about a stopper that is designed in such a way to provide some shock resistance?
There could be many design possibilities.
Thoughts?
Stupid idea (No. 87)?

[fishwife]

Perhaps not a stupid idea I can imagine a chain stopper mounted on a vehicle shock absorber, fixed so that the compression arm points aft. Even a coiled spring of sufficient strength would do the job.

P.

[Sandero]

I use a brain on braid 3/4" nylon line for the snubber which includes a heavy rubber mooring compensator which adds a lot of stretch and strain relief.

The compensator is above the water surface so I can observed the additional tension - it unwinds and the snubber stretches a bit. This tells me visually that the anchor is set and not dragging.

Without the compensator the snubber and the rode would appear the same if the hook were set or dragging along the bottom.

The snubber unwinding is a "tell tale" indicating that the rode is under tension ergo the anchor is set.

Try it, you'll like it.

[James S]

Originally Posted by fishwife

Perhaps not a stupid idea I can imagine a chain stopper mounted on a vehicle shock absorber, fixed so that the compression arm points aft. Even a coiled spring of sufficient strength would do the job.

P.

Thats what I'm thinking...the trick would be to have it absolutely positive in the event of any failure of the "shock bit"
Time to do some sketches

[nautical62]

I use a length of retired climbing rope with a stainless carabiner. Held up great in the 45 knot cold front here in the Bahamas a few nights ago. I've considered using webbing to prevent chafing, but it's held up well and I figure it's easier to just replace the rope if it wears.

[Tom Hildebrandt]

I am rethinking all of these issues after the past six years off travelling from Australia to the Carribean via Africa.

If I can get a rope/chain combo gypsy for my Muir Cheetah windlass, I am going to go with two identical rhode chain combinations that could be used for any anchor I have available. Each system will be between 200 feet of chain 3/8 HT plus an equal length of three strand nylon 12 mm rode. When in deep water, and I use more than 200 feet of chain, the "snubber" will be built into the system.

Under normal anchoring I seldom use more than 200 feet of chain, so a snubber will be necessary. I will use a simple chain hook, again 12mm three strand nylon, and the length of the snubber will be about 50 feet. In normal conditions, I would only use 10 feet or so of the snubber, secured to a welded cleat on deck. If necessary for chafe protection, a standard hose (almost any type) of sufficient diameter will fit through the chock where chafe is likely to occur. If there is to be significant surge loading in shallower water, I will just use more snubber line. (Note to self, have a second snubber line in case it is necessary to deploy both anchors in shallow waters)


I am also thinking of installing a chain stopper, through bolted or perhaps welded, to the deck between the windlass and the roller. The intention of this is to take the surge loading in swells and/or stronger winds when retrieving the anchor and the snubber is not in place, and to act as a safety device in case the gypsy wheel becomes stripped or lets go for some reason.

Regards

Tom

PS If I can not get a combo gypsy, then I will go back to what I had previoulsy, 100 meters all chain, with the long snubber as described and a second rode chain, but only with 40-50 meters of chain and 200 feet of the rode.

[Tom Hildebrandt]

Originally Posted by nautical62

I use a length of retired climbing rope with a stainless carabiner. Held up great in the 45 knot cold front here in the Bahamas a few nights ago. I've considered using webbing to prevent chafing, but it's held up well and I figure it's easier to just replace the rope if it wears.

What kind of stretch quality do the climbing ropes have?

Cheers

Tom

[Tom Hildebrandt]

Originally Posted by nautical62

I use a length of retired climbing rope with a stainless carabiner. Held up great in the 45 knot cold front here in the Bahamas a few nights ago. I've considered using webbing to prevent chafing, but it's held up well and I figure it's easier to just replace the rope if it wears.

What kind of stretch quality do the climbing ropes have?

Cheers

Tom