# What kind of anchor snubber?



## soulfinger (Aug 21, 2008)

I have a Catalina 350 that came with a Bruce anchor and an all-chain rode. I obviously need some sort of snubber to use with it, but can't really decide what's the best way to go. There's various chain hooks and such out there, or I could just put a shackle on the chain. Any suggestions on what I should get? How thick/what kind of line should I use?

I'm looking for a farily cost effective solution here; it'll be used in the near term for anchoring in the mud around Galveston bay; I don't think we'll be using it all that often.


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## Faster (Sep 13, 2005)

The right-sized chain hook spliced onto a 6- 10 foot three strand nylon strop should do the job, I'd think that a 5/8 or 3/4 strop would be plenty. A shackle is too difficult to remove in a hurry (in the middle of the night, for example)

I also think you'll find yourself using it quite a lot.. it really softens the pull and limits noise if there's any motion at all.


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## Vasco (Sep 24, 2006)

Get 30 feet of 5/8 nylon 3 strand and splice a stainless chain hook on it. In most conditions you'll not use all thirty feet but when it starts honking you'll have it. 5/8 is ideal for your size and will stretch nicely giving you the needed elasticity.


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## sailingdog (Mar 19, 2006)

I'd second what Vasco said, but recommend going with 45-60' of snubber... *since in many situations, when it starts to really blow, you'll want to let more scope out. If the snubber is too short, you won't be able to do that without hauling it in to unhook the snubber and then letting out the scope and then re-attaching the snubber. *If you have a long snubber to begin with-you can just ease out both the chain and snubber to add scope. _ A 45' snubber would allow you to let you go from 5-to-1, up to 7-to-1 scope in 15' of water, assuming you had let out about 10' of snubber initially. 

_A longer snubber also allows you to adjust it more easily to spread chafe out along more of the snubber...


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## camaraderie (May 22, 2002)

Dawg has it right about the length. I suggest buying TWO 3 strand dock lines of the same size you use at the dock with the spiced eyes already done. Buy a galvanized large shacle and put the loops on the shackle body...then buy a galvanized chain hook of the right size for your chain and put the shackle pin through the hole in the hook. Seize the shackle pin with monel wire and you are done.


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## funsailthekeys (May 15, 2008)

I use 20' of 1/2" 3 strand. I have a hook spliced on one end on a thimble to fit the chain and the other end has a large eye splice to fit over the deck cleat leading over the bow roller. Since there is about a 60% strech factor it has served well for 6 years on a 45, 26,000 boat with no signs of wear.


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## sailingdog (Mar 19, 2006)

That might be fine as a lunch hook snubber, but if you're anchored out over night and a storm hits when you're asleep, I would be hesistant to be sitting on a 35' boat using a 1/2" diameter snubber.


funsailthekeys said:


> I use 20' of 1/2" 3 strand. I have a hook spliced on one end on a thimble to fit the chain and the other end has a large eye splice to fit over the deck cleat leading over the bow roller. Since there is about a 60% strech factor it has served well for 6 years on a 45, 26,000 boat with no signs of wear.


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## SVAuspicious (Oct 31, 2006)

I use these:










35 feet of 5/8" nylon spliced around thimbles shackled to Wichard chain hooks. After the picture was taken I served the splice to the thimbles to reduce the chances of the thimble rotating.

sail fast, dave
S/V Auspicious


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## ANCORALATINA (Aug 24, 2008)

First beware of « Wichard chain hooks » as their breaking strength is quite low.

*Snubber:*

The main purpose of a snubber is to give *ELASTICITY* that an all chain rode doesn't have.

To have the max of elasticity, you need to have:
-	the *longest snubber *you can afford (45 to 60' is OK).
-	the *smallest diameter* in relation to the strength of your mooring line
-	For a 35' boat we suggest a 8 mm chain (5/16) (_breaking strength 3200 daN_)
-	The corresponding three strand Nylon rope will be a diameter of 12 mm (1/2'') (_breaking strength 3000 daN_)

João Nodari


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## funsailthekeys (May 15, 2008)

I've used mine in 50+ knots and haven't had a problem. I must mention that the chain is 3/8" and the water is usually about 25-35 feet deep, so the weight and angle of the chain does act as a bit of buffer.


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## Vasco (Sep 24, 2006)

One other thing I put three feet of vinyl hose on mine for chafe. I use 1" hose on my 5/8 snubber. To prevent the hose from running I use a hot spike to put a hole in it and thread a small line through the hole. When you're all set tie the line to the snubber and it won't run.


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## SVAuspicious (Oct 31, 2006)

ANCORALATINA said:


> First beware of « Wichard chain hooks » as their breaking strength is quite low.


João,

True. The chain grip I use is rated at only 1000# working load. When heavy weather is imminent I shackle directly to the chain. If you have a more effective solution I would be pleased to hear it.

sail fast, dave
S/V Auspicious


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## sailingdog (Mar 19, 2006)

SVA-

The best chain snubber hook I've seen is a flat stainless steel plate that is about 4" x 6" x 1/2" with two holes in it and a short slot cut into it. The slot slips around the chain, the two holes are for shackles that are attached to a snubbing bridle.


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## soulfinger (Aug 21, 2008)

Hmmmm....I can't say I'm really much less confused, but at least I have some good ideas. It seems like there are a lot of different schools of thought. 

Here's a dumb question: how does a chain hook work? It seems like it would/could fall out unless tension is maintained on the chain.


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## camaraderie (May 22, 2002)

soul...tension IS maintained by hauling on the snubbers till there is significant slack on the chain between the hook and the boat. But the fact that the hook CAN fall off (usually in totally benign conditions...never when there is a load on) is a good reason to use a chain stopper on deck as well to prevent strain on the windlass.


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## sailingdog (Mar 19, 2006)

BTW, the chain stopper, if you have one, should have a damn big backing plate on it.


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## HenkMeuzelaar (Feb 22, 2004)

We religiously use snubber lines while anchoring on chain rodes. However, my primary purpose is to reduce the amount of wear and tear on deck hardware, as well as to dampen chain noise belowdecks, rather than to try and rectify any real or perceived shortcomings of inelastic anchor rodes with regard to overall holding power of the anchor. 

Fortunately, protecting deck hardware from inelastic shockloading by chain rodes only requires a modest amount of elasticity. Just think of the clear difference between dropping a ceramic plate on a wood floor instead of a concrete floor. The wood floor must only have moved a few thousands of an inch...

Although it may be tempting to go to longer, stronger and more elastic snubber lines -- as evident from the discussions in this thread -- we should try to avoid creating what is know as a "kinetic rope" (more precisely a kinetic energy recovery rope - KERR) in the world of offroad wheeling and caterpillaring. 

The purpose of a KERR, typically made of the same elastic nylon rope used for snubber lines, is to transfer kinetic energy delivered by the towing vehicle while the rope stretches, into potential energy that is going to be ADDED to the energy that the towing vehicle can deliver as soon as the rope is fully stretched. 

There are some You tube videos, I believe, that show the awesome power of the KERR technique, e.g. when extracting battle tanks from the mud. The forces created should be intimidating to anyone who realizes that KERR ropes have at times pulled vehicles from the mud while leaving their wheels and axles behind. Also, a second belay line needs to be used in case the KERR line, or one of its hooks/shackles or attachment points break, since the resulting whiplash has at times catapulted hooks or shackles straight through radiators or even imbedded them in engine blocks.....

Perhaps you might argue that circumstances at anchor are very different. But, are they really.....? Some of us have probably experienced being trapped in an anchorage with substantial waves rolling in, or even breaking around us, with the bow of our vessel being driven back with great force. I submit, that under such wave-generated impact conditions (or even impacts generated by sailing wildly at anchor), the boundaries between KERR snatching and anchor snubbing are likely to be vague at best and nonexistent at worse.

If so, what practical consequences are there to be distilled for sailors? 
IMHO: 
(1) the elasticity of a snubber line (or an elastic anchor rode itself) is at best a two-edged sword; under certain conditions the destructive forces on anchor and deckware are likely to be amplified instead of reduced; 
(2) therefore the minimum amount of elasticity necessary to control shockloading on deckware is likely to be the optimum choice; and 
(3) under dynamic load conditions snubber lines should be treated with the same respect off-road recovery specialists treat their KERRs (i.e. one should keep one's distance and the rope should be replaced regularly).

Have fun!

Flying Dutchman


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## ANCORALATINA (Aug 24, 2008)

SVAuspicious said:


> If you have a more effective solution I would be pleased to hear it.
> S/V Auspicious


I've been using this very simple hook, during YEARS of full time living aboard










This is the type described by Sailingdog, it NEVER have fall of.

Note the small hole at the corner opposite to the slot, you can attach there a small line and remotely remove the hook (with the chain under tension)

Happy anchoring

João


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## Vasco (Sep 24, 2006)

Here's what happens when your snubber is too short. Took this picture of a Gulfstar anchored behind me a couple of years ago. Snubber snapped. His jib sheets are a bit slack too.  Chain hook's hanging in good though.


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## sailingdog (Mar 19, 2006)

vasco-

His snubber didn't snap, more likely it was chafed through by the CQR anchor sitting on the bow roller...


Vasco said:


> Here's what happens when your snubber is too short. Took this picture of a Gulfstar anchored behind me a couple of years ago. Snubber snapped. His jib sheets are a bit slack too.  Chain hook's hanging in good though.


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## Vasco (Sep 24, 2006)

Might be the case. I think it was a bit short if you look at where the hook is. The chain aft of the hook (bar tight in the pic) was the part that should have been slack and hanging down in a bight.


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## sailingdog (Mar 19, 2006)

True, but it doesn't matter if it was longer, the anchor probably would have chafed through it regardless of length.


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## SVAuspicious (Oct 31, 2006)

sailingdog said:


> The best chain snubber hook I've seen is a flat stainless steel plate that is about 4" x 6" x 1/2" with two holes in it and a short slot cut into it. The slot slips around the chain, the two holes are for shackles that are attached to a snubbing bridle.


I appreciate the response, but disagree. I want a snubber I can run to one bow cleat so that if wind and swell are coming from different directions I can run a second snubber aft to a midship or aft cleat.


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## sailingdog (Mar 19, 2006)

SVA-

The design I'm talking about can be used with one or two snubbing lines. It would be ideal for what you're talking about since you could always use a longer snubbing line on one side and then run that further aft if you need to change the angle of the boat to the wind. 



SVAuspicious said:


> I appreciate the response, but disagree. I want a snubber I can run to one bow cleat so that if wind and swell are coming from different directions I can run a second snubber aft to a midship or aft cleat.


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## JHJensen (Sep 9, 2008)

There are two excellent articles on snubbers from the latest issue of Passagemaker Mag.

*Sizing the capble snubber* Sizing the Capable Snubber - Web Exclusive Articles - PassageMaker Magazine

*Snubber FAQs*
Snubber FAQ's - Web Exclusive Articles - PassageMaker Magazine


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## HenkMeuzelaar (Feb 22, 2004)

That Passagemaker article provides useful data on static rope characteristics and on ways to attach a snubber but is alas quite naive in two dynamic aspects, namely:

(1) the author's assumption that wave action could at most double the wind force (in spite of the two orders of magnitude larger viscosity of water compared to air); and

(2) their failure to consider the kinetic aspects of rope stretch (as discussed in my kinetic energy recovery rope remarks earlier in this thread) which could lead to anchors (or deck hardware) being snatched out unceremoniously, particularly under wave-induced shockloading conditions.

Have fun

Flying Dutchman


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## sailingdog (Mar 19, 2006)

Thanks for the link to those two articles. I'm biased, since they clearly support my philosophy on snubbers... 

A snubber of less than 9/16" diameter or 45-60' length is really not sufficient for most boats 28' or greater LOA. Ancoralatina underestimates the amount of damage a 1/2" snubber line can do when it parts—not to mention what the shockloading—that will occur when the snubber parts—can do to the ground tackle system.


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## HenkMeuzelaar (Feb 22, 2004)

SD,

Go take your 9/16" dia 45' long nylon line and snatch a couple of 1 ton vehicles out of the mud.

After that, please explain to yourself why your anchor is supposed to stay put once your perfect KERR reaches full stretch and your vessel is still moving backwards on top of that big wave.....

Flying Dutchman
(veteran of 2 Landrovers, 1 Jeep and 3 Ford Rangers)


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## soulfinger (Aug 21, 2008)

The Dutchman's physics seem to make sense (I like physics). But what about all the boaters who use nylon rope anchor lines instead of all-chain? Aren't the creating super-sized kinetic ropes? Shouldn't all their deck cleats be ripped out? The ability of a kinetic rope to store kinetic energy should be proportional to the lenght of the rope (shouldn't it?)


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## sailingdog (Mar 19, 2006)

Henk-

Most of the vessels in question are not puny one-ton vessels, and the physics of hauling a jeep out of the mud and a sailboat in water are not quite the same thing.


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## soulfinger (Aug 21, 2008)

I will take exception to your comment about physics---yes, physics are all the same, that's the beauty of it. Newtonian physics works for everything, unless you're really small, really huge, or at really high or low energy. When things seem like they're breaking the rules, that usually means you're not thinking about things in the correct manner. That is the case here.

I had to blow the dust out of parts of my brain that haven't been used in a while; after thinking about it for a while, I think I can finally resolve the apparent contradiction between the utility of anchor snubber, and of a kinetic rope. 

The frame of reference here is the cleat on your boat that it's all attatched to; nothing else really matters. Recall that Force = Mass x Acceleration (F=MA). There is some force (measured in Newtons) that will rip the cleat off your boat; that's what we are all trying to avoid. 

The wind and waves act on your boat, and push them away from the anchor. When you run out of slack in your anchor rode, it goes taught and decelerates (negative acceleration is still acceleration) the boat. If you're using all chain, the deceleration will occur extremely rapidly, resulting in a really big force (recall F=MA). An elastic rode (the snubber) reduces the rate of deceleration of the boat (resulting in a smaller force on your cleat). It does that by temporarily storing some kinetic energy as potential energy as it stretches. It "bleeds off" that stored energy as the snubber returns to it's normal length. 

So the Dutchman is absolutely correct, a kinetic rope can be used as machine to temporarily store some kinetic energy as potential energy. In the right situation, that energy can be used to great effect. However, the amount of force it generates is actually less than that of an inelastic rode---mathematically, it has to be less, because the acceleration is less (can't escape F=MA). 

Using a kinetic rope to free a vehicle stuck in the mud uses the same forces, just differently (I figured this out watching YouTube!). It takes a quick "wham" from the towing vehicle and translates it into a longer sustained pull on the stuck vehicle. It allows you to combine the motive power of the towing vehicle (which probably isn't much on a slick, muddy road), plus the momentum of the moving towing vehicle. The kinetic rope combines those forces and translates them into a longer, stronger pull. 

This may be more than anyone wanted to hear, but I salute the Dutchman for throwing in a contrary opinion. Remember: the rules of physics are extremely inelastic (pun intended).


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## sailingdog (Mar 19, 2006)

Soulfinger—

My point is that the problem is that the two situations aren't the same. When you pull a vehicle free from mud, the resistance drops incredibly... A boat pulling on a snubber never leaves the water—the snubber will tend to pull the boat down into the water if anything. The boat will still have a fair amount of resistance from the water, regardless of whether it is moving away from or towards the anchor. 

Also, the viscosity difference between mud and air is much greater, so the potential release of energy at the change over point is much higher. The resistance the water exerts on the boat has a damping effect of sorts. A jeep on a slack tow rope shock loads the rope in ways a boat really can't. A boat can't generally shock load the anchor rode to the same degree a tow vehicle can—the inertia of the boat, which is generally far more massive than the jeep, the elasticity of a long snubber, and the resistance of the water—really prevent it from making very dramatic changes in acceleration or deceleration. Unless the boat is hit and pushed by a breaking wave, most of the forces on the anchor will be relatively gradual in change because of all the give in the various parts of the system. 

If the line breaks—then you've got a huge problem since a lot of the potential energy stored in the line will be released in a single event. I know that people have been injured and killed by a breaking line under heavy load. 

Using a thin snubbing line will likely increase the chance of the line snapping under the dynamic loading situation of a boat at anchor in a storm. A heavier snubbing line is far less likely to reach its breaking limit.


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## ANCORALATINA (Aug 24, 2008)

sailingdog said:


> A heavier snubbing line is far less likely to reach its breaking limit.


Absolutely true!

Then why not using a *CHAIN *as a snubber??

The main (_if not the only_) reason of a snubber is to give « *ELASTICITY *» and the heavier snubber, the less elasticity.

As usual it is a compromise, but if you use a snubber that is not elastic, why using a snubber??

João


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## sailingdog (Mar 19, 2006)

[EDITED by JRP]. *I'm not saying you should use an inelastic snubbing line... just that you shouldn't use too light a snubbing line. *After all, if the snubber breaks, it can't do it job, and the act of it breaking can be very dangerous to anyone nearby. The shock loading of the snubber breaking could easily damage the ground tackle on the boat.

There are two things that give a snubbing line elasticity. The first is how thin it is... a thinner line will be more elastic given the same load as a thicker line. However, the second way a snubber is given elasticity is length. A longer snubbing line is more elastic than a short one. I have only recommended using a fairly thick, fairly long snubbing line for this reason.

This is why I don't recommend a thick, short snubber. It isn't safe. A short thick snubber doesn't have the elasticity required to function properly.



ANCORALATINA said:


> Absolutely true!
> 
> Then why not using a *CHAIN *as a snubber??
> 
> ...


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## SVAuspicious (Oct 31, 2006)

sailingdog said:


> [EDITED by JRP]


That isn't really necessary, is it?



sailingdog said:


> There are two things that give a snubbing line elasticity.


The nice thing about elasticity is that it is linear and singularly variate. F=kx where k is a factor based on the material and construction and x is the extension.

The problem with chain is that the k is so very high once the links are fully in contact over the total length of the chain, ignoring catenary effects that may in fact be relevant (see Alain Fraysse's work on that subject).

Without doing a dynamic analysis, it seems to me that as k increases (larger diameters of line using 3-strand nylon) less energy is stored in the line before significant shock is transmitted to the boat.

And by the way, stored kinetic energy is called potential energy. The physics is clear in this regard. <grin> Kinetic energy is by definition energy associated with a mass in motion.

I guess I'm feeling a little pissy this afternoon.


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## sailingdog (Mar 19, 2006)

SVAuspicious—

I also tend to recommend octo-plait nylon over double braid or three-strand laid lines, since it has almost no tendency to hockle and a bit better elasticity characteristics than either double-braids or three-strand laid lines.


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## SVAuspicious (Oct 31, 2006)

sailingdog said:


> I also tend to recommend octo-plait nylon over double braid or three-strand laid lines, since it has almost no tendency to hockle and a bit better elasticity characteristics than either double-braids or three-strand laid lines.


I haven't measured or found existing measurements for 'k' of various line. I suspect that if someone does make that effort 'k' would be lowest for the multi-plait lines increasing through 3-strand and on to double-braid. "Better" is dependent on application.

IMHO, for anchor rode I do like either multi-plait or 3-strand. For snubbers I am happy with 3-strand but would go to a lower 'k' (multi-plait) before higher (double-braid).

All of that is independent of working load and breaking strength of course. It should be noted that working load is a convention based on an accepted (or not *grin*) safety factor below either breaking strength or the range of elastic deformity. Pick a number, but you better know what you are doing. We're talking about engineering here, not science.


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## soulfinger (Aug 21, 2008)

Agreed; no name-calling is neccessary here. 

I think the bottom line here is that thickness gives you strength, which we all agree is good. However, as you go thicker, you're going to also need to go longer to retain similiar elasticity (in terms of displacement, not "k" value).

You know, there has be a dumb joke in here about about "Captain Hooke", but I just don't have the energy.


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## xort (Aug 4, 2006)

sailingdog said:


> [Edited by JRP]


Real nice, dog

I understood what he meant and what he said has merit.
You agreed by saying that a short thick snubber will not have elasticity.


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## sailingdog (Mar 19, 2006)

Xort-

I'm not the one saying that one should use chain as a snubber... and taking someone else's posts completely out of context.


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## jasonr575 (Sep 12, 2006)

still no need to be so aggressive, you have done this on numerous occasions, how about cutting it out and keeping on topic. 
speaking of, i have not used a snubber before, i am switching over to all chain in the spring, how mutch slack to i put in the chain when connecting the snubber? is there a particular way of doing it or do you just make it tighter than the chan and leave it at that or what


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## sailingdog (Mar 19, 2006)

Jason-

You want to have enough slack that the chain doesn't snug up before the snubber stretches to its maximum, otherwise, there's not point in having a snubber. 


jasonr575 said:


> speaking of, i have not used a snubber before, i am switching over to all chain in the spring, how mutch slack to i put in the chain when connecting the snubber? is there a particular way of doing it or do you just make it tighter than the chan and leave it at that or what


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## jasonr575 (Sep 12, 2006)

thanks, but is there a particular measurement or is it just a guess?


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## sailingdog (Mar 19, 2006)

It depends on what specific rope you're using and such...but you don't have to be that precise about it...  It isn't rocket science-you just want to have enough slack in the chain that the boat doesn't come up hard against the chain unless the snubber has snapped.

BTW, you should never use the windlass as a termination point for the chain. The chain and the snubber should be tied off to proper cleats, mooring bitts or a samson post. Most windlasses aren't designed to act as a termination point for an anchor rode-and doing so will usually damage the windlass.



jasonr575 said:


> thanks, but is there a particular measurement or is it just a guess?


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## xort (Aug 4, 2006)

sailingdog said:


> Xort-
> 
> I'm not the one saying that one should use chain as a snubber... and taking someone else's posts completely out of context.


his point was that going too far with a heavy rope you might as well use a chain. I totally understood what he was saying. there is a balance between too thin/breaking easily and too strong/no elasticity.

Your response was totally uncalled for. you do this a lot. [EDited by JRP]


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## jasonr575 (Sep 12, 2006)

thanks sailing dog now thats constructive feedback. another question came to mind, is there a proper way to cleat a chain off to a cleat. Or does everyone just cleat it like a line


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## sailingdog (Mar 19, 2006)

That's your opinion, but I disagree. I wasn't suggesting using 2" diameter rope or anything unreasonable, especially given the size and weight of the boat in the OP. I understand that there is a balance between going too thin and elastic, and too heavy and inelastic. He was jumping to a conclusion that was unwarranted by my post as far as I am concerned, and quoting me out of context. 


xort said:


> his point was that going too far with a heavy rope you might as well use a chain. I totally understood what he was saying. there is a balance between too thin/breaking easily and too strong/no elasticity.
> 
> Your response was totally uncalled for. you do this a lot. [Edited by JRP]


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## JohnRPollard (Mar 26, 2007)

Gentlemen,

We received a non-specific complaint about personal attacks on this thread. I just read back a few pages and saw several examples from different individuals that could easily qualify. Please refrain from using personally insulting language -- it's not constructive and it violates forum guidelines. Also, editing your posts is not how we like to spend our time.


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## JHJensen (Sep 9, 2008)

*Securing a chain rode and snubber*



jasonr575 said:


> ... is there a proper way to cleat a chain off to a cleat.Or does everyone just cleat it like a line?


Jason the device you use to secure your rode and take the load off the windlass is called a *chain stop/stopper*. (You never just take a chain to a cleat or Samson post.) The stop is mounted on the deck between the windlass and the bow roller. For photo you can do a search on Sailnet or another site. Ideal and Lewmar make their own to go with their gear. A chain stopper will also keep your chain from running out uncontrolled when raising the anchor should there be a failure of the windlass brake to hold that chain which has already been retrieved All of this gear should be installed according the manufacturers instructions. The chain stop needs to be installed with a beefy backing plate. The chain stop will work under normal working loads as long as there is a cantenary (curve/sag) in the rode and proper scope has been released. When the weather kicks up to the point where rode is coming up taught (no centenary) hopefully before&#8230; you will then apply a proper anchor snubber of sufficient length to absorb the shock loads. Picking the proper snubber is covered very well in those two articles I referenced earlier in the thread from the latest issue of PassageMaker Magazine as well as some of the other posts.

I can't emphasize enough that anchor and deck gear be set up properly or it is an accident waiting to happen. People have been horribly maimed or killed by not knowing how to use these important systems. You should practice in calm weather to know how to use this equipment and devices.

Last when you install your deck gear, it should be done in compliance with applicable ABYC Standards. If your system was factory installed these are the standards your builder should have consulted as they were designing the systems on your vessel and if you are having an upgrade done to an older vessel you should request that the work meet applicable standards and regulations.

Below is a section of H-40 to give you an idea of what is involved: (*This not the complete standard as others may apply as well.*)

ABYC Standard H-40 Anchoring Mooring and Strong Points July 2008 is the most important one. (Always reference the latest version if possible)

"40.5 ANCHORING AND MOORING
40.5.1 General
40.5.1.1 All boats shall be equipped with fittings, including a strong point, so that they may be anchored by the bow and secured to a dock or mooring.
40.5.1.2 All fittings or parts of a boat that may change the direction of pull of the dock line and anchor rodes shall be smoothed and rounded to a radius of not less than one-half of the diameter of the maximum intended line size [e.g., a 1/4 inch (6.5 mm) radius for 1/2 inch (13 mm) diameter line].
40.5.2 Materials
40.5.2.1 The anchor shackle, or other means of attaching the anchor to the rode, shall exceed the minimum breaking strength of the weakest component of the ground tackle. (See Ap.Table I.)
40.5.2.2 Materials shall be selected to minimize galvanic corrosion (see ABYC E-2, Cathodic Protection.)
40.5.3 Design and Construction - General
40.5.3.1 For boats over 20 ft (6 m) in LOA, provision shall be made for the deployment of two anchor rodes over the bow.
40.5.3.2 Chocks
40.5.3.2.1 If only one bow chock is used, the opening shall be of sufficient size to accommodate two anchor rodes of the recommended size, plus chafing gear.
40.5.3.2.2 If two bow chocks are used, each shall be of sufficient size to accommodate the recommended size of dock line or anchor rode, plus chafing gear.
40.5.3.2.3 Chocks shall be fastened to withstand the forces applied by an anchor line subjected to the permanent mooring loads in Table I. 
40.5.3.2.4 Chocks shall be mounted to minimize bends in the line, and to prevent the rode from chafing at the toe rail, deck, or rub rail. NOTE: To minimize stretch, cleats shall be mounted as close as practicable to the chock.
40.5.3.3 Anchor Rollers
40.5.3.3.1 If only one anchor roller is used, it shall be of sufficient size to accommodate two anchor rodes plus chafing gear. The designed working surfaces of the anchor roller shall be smooth and rounded to a radius not less than three times the diameter of the maximum intended line size. The working surface and edges of the structure
shall have a radius one-half the diameter of the maximum intended line size.
40.5.3.3.2 Anchor rollers intended for mooring shall have a safe working load at least equal to the mooring load in Table 1.
40.5.3.4 Strong Points
40.5.3.4.1 Strong points shall be of sufficient size to accommodate two anchor rodes or dock lines.
40.5.4 Installation
40.5.4.1 Anchors stowed on deck shall be secured so that they will not break loose when subjected to a vertical force equal to five times the weight of the anchor.
40.5.4.2 Strong points shall have a safe working load greater than, and be fastened to withstand, twice the permanent mooring loads in Table I.
40.5.4.3 Windlass or Capstan
40.5.4.3.1 *A windlass or capstan, if installed, shall be fastened to withstand three times the rated capacity of the windlass.*
40.5.4.3.2 The structure to which the strong point is fastened shall be designed and constructed to withstand twice the permanent mooring loads in Table I.
40.5.4.3.3 *Boats equipped with an anchor windlass shall be equipped with a chain stopper, bitt, cleat, or Samson post to permit the transfer of the load from the windlass.*
NOTE: *A windlass or capstan is not considered to be a strong point to be used for securing an anchor rode
to the boat.*" (Excerpted from ABYC Standard H-40 7/08)

I could not get the Tables 1 and 2 to paste If someone could contact me and tell me how to post things like that I would be most grateful.  
Note: If you want to see Tables 1 and 2 pm me with your email address.

This link is to an interesting article on rodes and calculating the catenary of a rode in both line and various sizes of chain.

Anchor Catenary

Have fun!

John
ABYC Master Technician
Maritime Educator,Trainer & Consultant


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## fcsob (Apr 28, 2007)

We use two 5/8 40 ft dock lines. Tie them to the chain with, I beleive sp, pursit knots and cleat them. No chain hooks or splices.


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## pdqaltair (Nov 14, 2008)

*Do you mean prusik hitch?*

The Prusik Knot or Triple Sliding Hitch

or is there such a thing as a purist knot?


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## bwindrope (Feb 25, 2007)

*I use a rolling hitch on 3/8 three strand*

What a thread, great stuff here. My two cents is that I have been following Nigel Calder's advice for some time and find it works great. Instead of using any hardware, I attach my 3/8 three strand nylon snubber line with a rolling hitch. I've weathered several 40 knot blows with this system and it has never slipped. Easy to tie and untie and no chafing problems. Page 711 of Nigel's book covers the details. He gives the rationale and the recommended line sizes there too.

Just what has worked for me.

Happy Solstice everyone!


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