How to use a snubber with a bowsprit?

[Kettlewell]

I still need to use some kind of snubber though as last night made clear if for no other reason to stop than the chain graunching.

This is an underrated problem! On our boat you can easily hear the chain (and/or rope) moving back and forth on the roller and I find it wakes me up at night, which can be a good thing if there is a change in the weather. However, if I am expecting the wind to remain the same overnight I will often take a stretchy rubber bungy cord and wrap it around the chain and roller in order to pad and limit the movements of the chain/rope on the roller--really quiets things down.

[Dockhead]

Originally Posted by poiu

You are right as mentioned above you need a chain stopper of some sort, but here, imagine the snubber stretches to max, which is rather a lot. 20% roughly. Then it snaps and you need the chain stopper to save you, but the boat is accelerating backwards under what will be extremely high loads and u less you have sized the length of the chain stopper line just right so momentum does not build the shock load is going to extremely high and likely to break something. Chain stoppers on big ships are never slack, so this doesn’t happen to them. You need either or I think.

Well, not "or". But for sure, some kind of damper on the chain belay would be a good thing, for the case where the snubber breaks. I've had a few snubbers break in my cruising lifetime; it never caused damage to the chain stopper, but the bang could be destructive under the right circumstances. [/QUOTE]

Originally Posted by poiu

I suppose I can answer my own doubts - if the chain stopper line was in nylon, triple strength of the snubber for example that may save the day. Not dyneema.

Once a piece of nylon is as strong as the chain, it's not going to be very elastic unless it's very long, but I suppose it's better than dyneema for shock absorption. I like dyneema for this not just because it's strong, but because it's highly chafe resistant, which nylon is not.



Some kind of damper could be arranged I guess.

Originally Posted by poiu

Unfortunately many cruising boats aren’t set up perfectly for anchoring as I am discovering and the vertical bow, bowsprit, only one anchor roller, no chain stopper, as per most new boats is not as good as it looks.. . .

I agree completely and would be more blunt than that. Totally unsuitable is what I would say.



I lack a bowsprit on my boat, and miss it for flying the A2. One of those retractable ones would probably be the thing. Two bow rollers and a raked bow are important for efficient anchoring.


My ideal foredeck would have a horizontal windlass (Lighthouse etc.) with a warping drum, a hella strong Samson post, substantial bulwarks, four and not two bow cleats, roller fairleads in the bulwarks. A strong chainplate nearer the waterline at the bow would probably be a good thing too.

[hpeer]

Originally Posted by Dockhead

Well, not "or". But for sure, some kind of damper on the chain belay would be a good thing, for the case where the snubber breaks. I've had a few snubbers break in my cruising lifetime; it never caused damage to the chain stopper, but the bang could be destructive under the right circumstances.

Once a piece of nylon is as strong as the chain, it's not going to be very elastic unless it's very long, but I suppose it's better than dyneema for shock absorption. I like dyneema for this not just because it's strong, but because it's highly chafe resistant, which nylon is not.



Some kind of damper could be arranged I guess.





I agree completely and would be more blunt than that. Totally unsuitable is what I would say.



I lack a bowsprit on my boat, and miss it for flying the A2. One of those retractable ones would probably be the thing. Two bow rollers and a raked bow are important for efficient anchoring.


My ideal foredeck would have a horizontal windlass (Lighthouse etc.) with a warping drum, a hella strong Samson post, substantial bulwarks, four and not two bow cleats, roller fairleads in the bulwarks. A strong chainplate nearer the waterline at the bow would probably be a good thing too.[/QUOTE]

I have a bow sprit and all the above excepting 4 cleats, only 2. But I have the Samson Post and a cleat on the Lofrans Falcon.

The bow sprit/bob stay combination can be a PITA as the bob stay will foul the anchor when raising/lowering and makes a mooring difficult, lines foul bib stay and chafe. I added a “spare”. Bob stay connection at the cut water to use as a snubber attachment, but it is a PITA itself. I moved the anchors forward to clear bob stay, helped greatly. I have a very substantial chain lock.

[hpeer]

A few years ago there was a substantial thread on snubber useage, material and size.

The argument I found compelling was the snubber should be long and thin enough to provide good elasticity. And YES, it needs to be backed by a substantial chain stop.

If you want elasticity AND strength then you need a longer snubber.

I have come to view the snubber as a consumable, it will wear and eventually break. This should be no big deal.

In STORM conditions the situation is somewhat different. Then you may want to apply a larger diameter rope, but you will lack elasticity.

To get fancy you may want to apply multiple snubbers, staged to add strength.

If you have no chain stop I suppose one could use an adequately sized soft shackle to a cleat or other strong point.

I should clarify my above post by noting my sprit is quite long, 5’ and my comments about the bob stay are relevant to this particular installation.

I think the KEY is the anchor layout needs to be adjusted to the vessel and conditions. I have made many changes, minor and otherwise, to get a happy solution.

[Peeew]

On that type of sprit with the chain exiting through a hole I rig a 2 leg nylon snubber to cleats near the bow. Usually 20ft or so on each leg. I splice an eye where they meet at the anchor chain. When I pull the anchor I pull the eye up with the chain through the sprit and disconnect only that end, storing the snubber in the chain locker. When setting the system inside a soft shackle to attach to the chain and let the chain out pulling the attached snubber eye with it. Works well and all the setting is done on deck. Similar to what many catamarans do.

[Dockhead]

Originally Posted by hpeer

. . . If you have no chain stop I suppose one could use an adequately sized soft shackle to a cleat or other strong point.. ..

There are a number of different ways to belay the chain besides a chain stop.


I use a stainless steel chain strop with chain hook on the end, made off to the inner forestay chainplate (a hella strong strong point).


You can also make a strop to take to a bow cleat or cleats.


A soft shackle might be a more secure way to connect to the chain than a chain hook, but I've never had an issue with a standard chain hook, which has the advantage of being capable of being connected or disconnected in one flick of one hand, provided it's unloaded, quite a bit faster and easier than connecting or disconnecting a soft shackle. Mantus make a really nice one which locks in place.


Anyone concerned about snatch loading the chain lock or strop in case the snubber breaks (when, not if) could organize some damping separate from the belay device. Maybe a short and thick nylon backup snubber which is not too elastic and so not too comfortable, but which will take the edge off the snatch load.

[Dockhead]

Originally Posted by dlj

I would definitely make that at least as strong as required for a hard point per ABYC. Plus, your snubber should be pretty darned close to as strong as your chain.

dj

Your snubber almost can't be as strong as your chain and still be elastic enough to snub. It would have to be very, very long, and thick. Don't forget to discount for cyclic loads and chafe.


Another data point on snubberless anchoring:


I'm sitting at this moment at anchor in a shallow anchorage (about 6 meters of water) with 50 meters of chain out, with the wind gusting into the 30's. I would normally put a snubber on in such conditions -- shallow water with only half my chain out greatly reduces the snubbing effect of the chain catenary. I decoded to continue the experiment and didn't put on any snubber.



But haven't come even close to a snatch load so far, in half a day of this. Still riding very comfortably.

[dlj]

Originally Posted by Dockhead

Your snubber almost can't be as strong as your chain and still be elastic enough to snub. It would have to be very, very long, and thick. Don't forget to discount for cyclic loads and chafe.

I follow John Harries' published advice on this subject. I'd highly recommend paying the very small yearly fee to have complete access to his web site. In my opinion, it's the best web site found anywhere for cruising sailors.

My snubber is about 60 feet long. I typically run out 25 to 45 feet, depending.

My nylon line is close to the same strength as my chain. With that kind of length, it does have enough elasticity. Yes, as I said before, my line is thick.

I inspect that line every time I retrieve it. I've replaced it three times in the past 3 years. Sounds like once a year, but actually not really. It's when it shows signs that it needs changing, so that depends upon how the anchoring conditions have been. It was actually once in 2 years, and twice in one year.

dj

[Dockhead]

Originally Posted by dlj

I follow John Harries' published advice on this subject. I'd highly recommend paying the very small yearly fee to have complete access to his web site. In my opinion, it's the best web site found anywhere for cruising sailors.

My snubber is about 60 feet long. I typically run out 25 to 45 feet, depending.

My nylon line is close to the same strength as my chain. With that kind of length, it does have enough elasticity. Yes, as I said before, my line is thick.

I inspect that line every time I retrieve it. I've replaced it three times in the past 3 years. Sounds like once a year, but actually not really. It's when it shows signs that it needs changing, so that depends upon how the anchoring conditions have been. It was actually once in 2 years, and twice in one year.

dj

I've been a subscriber for many years. I agree it's a great resource.

Yes, if you make the snubber long enough, you can make it stronger.

But it's very hard and perhaps impossible to make it really as strong as the chain, once you consider weakening from cyclical loading (nylon is very susceptible to this), from being wet (nylon again), and from chafe (nylon). The sudden failure of nylon ropes at far less than their rated strength is well-documented. This is essential reading: https://www.cruisersforum.com/forums...4&d=1506084876

John uses a chain stopper in addition to a snubber, but wrote here: https://www.morganscloud.com/2020/02...n-and-marking/ that he doesn't think a chain stopper is strictly necessary.

I disagree with him for the reasons discussed in this thread. I've corresponded with him about this and I thought he was going to change the article, but he hasn't.

People reading this can make up their own minds.

You wrote "My nylon line is close to the same strength as my chain." Well, that would be the case only if the rated strength were 3x or 4x the rated strength as the chain. Nylon has to be severely derated for (a) cyclical loading; (b) being wet; (c) any chafing (and once a snubber is pretty long, it may chafe on the bottom or get cut on rocks too). I think it's worth saying again -- trying to get your snubber, especially a nylon snubber, to do the job of a chain stopper or other chain belay, is a really bad idea, as it's inherently unsuitable for that task.

[Dockhead]

"While doing research for a new book on heavy weather tactics, Surviving the Storm, we encountered several instances where new nylon rodes had failed when used in conjunction with parachute anchors under storm conditions. In all cases the failures were at loads well below the catalog breaking strength of the rode, and external chafe did not seem to play a part in the equation. . . .

"Further investigation with rope manufacturers revealed several startling facts. First, the rated strength of nylon drops by 15 to 20% when it is wet, as compared to the catalog breaking strengths (which are dry rated). Second, when nylon is repeatedly cycled at a high percentage of its breaking strength, typically above 50%, it generates substantial amounts of internal heat. This internal heat degrades the structural performance of the nylon, by as much as half, and is thought to be a common cause of failure at high loads. This internal heating process is worse when the rope is wet." [Emphasis added.]

https://www.cruisersforum.com/forums...4&d=1506084876

All of us experienced cruisers have experienced a sudden failure of a nylon snubber at some point or another -- it happens all the time. A nylon snubber should NOT be the only thing you want holding your ground tackle to your boat.

[hpeer]

My attitude, although I have not had to try it, is to use a light snubber (always) for comfort. If a really nasty is coming, +30-40kts, then use a larger snubber. If really really nasty then use multiple snubbers (repurposed dock lines).

Multiple solutions are allowed.

The only trouble I have is moorings. I can’t find a way to make a bridle work. Unusual bow set up, 5’ sprit with anchors forward and outboard. Works great for anchoring but on a mooring the hob stay wants to cut the bridle AND frequently spins around making a mess to let go.

We very rarely take a mooring anyway.

[dlj]

Originally Posted by Dockhead

I've been a subscriber for many years. I agree it's a great resource.

Yes, if you make the snubber long enough, you can make it stronger.

But it's very hard and perhaps impossible to make it really as strong as the chain, once you consider weakening from cyclical loading (nylon is very susceptible to this), from being wet (nylon again), and from chafe (nylon). The sudden failure of nylon ropes at far less than their rated strength is well-documented. This is essential reading: https://www.cruisersforum.com/forums...4&d=1506084876

John uses a chain stopper in addition to a snubber, but wrote here: https://www.morganscloud.com/2020/02...n-and-marking/ that he doesn't think a chain stopper is strictly necessary.

I disagree with him for the reasons discussed in this thread. I've corresponded with him about this and I thought he was going to change the article, but he hasn't.

People reading this can make up their own minds.

You wrote "My nylon line is close to the same strength as my chain." Well, that would be the case only if the rated strength were 3x or 4x the rated strength as the chain. Nylon has to be severely derated for (a) cyclical loading; (b) being wet; (c) any chafing (and once a snubber is pretty long, it may chafe on the bottom or get cut on rocks too). I think it's worth saying again -- trying to get your snubber, especially a nylon snubber, to do the job of a chain stopper or other chain belay, is a really bad idea, as it's inherently unsuitable for that task.

Johns web page clearly stated that the breaking strength, not the working load limit, should be about the same. You are mixing those two concepts it would appear from your statement above.

We will just have to agree to disagree I imagine. I do not feel it is inherently unsutable. Neither has anyone commenting on Johns post identified this in the comments.

As to nylon ropes not all being equal, I have to say my personal experience has shown that to be very much the case. I bought a polyamide line in Europe that was excellent. Polyamide is the material name, nylon is a trade name used more often in the US as I understand it, but that is the same material. There was a discussion on Johns web page about different manufacturers here in the US with one manufacturer standing out. I'd recommend reading about that aspect.

I'm not disagreeing that your system is in any way inferior or wrong, but it clearly has some compromises, as all things in boating have. But you are stating that using a nylon snubber is inferior or wrong. That I disagree with.

dj

[Dockhead]

Originally Posted by dlj

Johns web page clearly stated that the breaking strength, not the working load limit, should be about the same. You are mixing those two concepts it would appear from your statement above.

I don't see what difference that makes -- whether SWL or break strength, nylon objectively does not live up to its rating when wet, under cyclical loads, etc. We've all had snubbers break so I think we all know this pretty well from practical experience.

Originally Posted by dlj

We will just have to agree to disagree I imagine. . . .

Of course. We are all responsible for our own boats, so it's up to every one of us to make his own judgement.


Note, by the way, that John does not indeed recommend using only one snubber as the only attachment of the boat to the ground tackle. He writes:


"In all cases I would back up the primary snubber with a second shorter and heavier one and make sure all crew members are well clear when the snubbers load up, but then we do that with a chain stopper too."

Originally Posted by dlj

I'm not disagreeing that your system is in any way inferior or wrong, but it clearly has some compromises, as all things in boating have. But you are stating that using a nylon snubber is inferior or wrong. That I disagree with. . .

Well, it's objectively true and not a matter of opinion, that nylon rope less than 2x or 3x the strength (SWL, breaking load, pick whatever you like) weakens the ground tackle AS A SYSTEM and creates a potential failure point. What is a matter of judgement is whether this loss of strength of the system is acceptable or not. Everyone has to decide that for himself, but I think it's useful to have these discussions and highlight these issues, which not everyone has thought about.

What's also true and possibly a defect in my system is that if a snubber breaks and you get a snatch load on a hard attachment like my stainless chain belaying strop, or someone's chain lock, that could break things and create a failure point.

I've never experienced that (in more than 40 years of cruising) but that doesn't mean it can't happen. Maybe a project for this winter will be to solve this.

A dyneema strop instead of chain, and with some kind of shock damping in it. Doesn't need to be as elastic as a snubber, just enough to take the edge off a possible shock load if a snubber were to break. Or maybe simpler just a really thick piece of nylon as someone suggested. That would no doubt be a significant improvement to my system. So these discussions help me too.




I'm standing at anchor as I write this, and yesterday went through a significant gale which lasted all day long, with gusts near 40 knots and whitecaps in the anchorage, and considerable boat motion. As an experiment -- inspired by this discussion -- I rigged a snubber but didn't deploy it -- didn't let enough chain out for it to start working. I wanted to see whether I would find the end of the damping effect of my chain catenary. I am in shallow water and with only half the chain -- 50 meters -- out, so much less catenary damping than in deep water with all 100 meters deployed.

Surprisingly we didn't seem to come anywhere near any kind of snatching up of the chain or any shock loading. Ride was smooth as it could be. I always use a snubber if there is a material chance of winds over 25 knots and/or wave action. I might loosen that rule now a bit. Certainly nothing under 30 knots is going to require a snubber.

[dlj]

Originally Posted by Dockhead

I don't see what difference that makes -- whether SWL or break strength, nylon objectively does not live up to its rating when wet, under cyclical loads, etc.

The difference seems to me from John's writing, has to do with the amount of stretch you get – using UTS vs SWL makes a major difference in line diameter sizing. If you are matching the strength of your chain at SWL, then it will be a lot larger diameter than if you size it to the UTS and you will get less stretch.

I don't really have any horses in the race – I'm really more interested in learning. So that comment is simply from an outside observation from what I'm reading.

Originally Posted by Dockhead

Well, it's objectively true and not a matter of opinion, that nylon rope less than 2x or 3x the strength (SWL, breaking load, pick whatever you like) weakens the ground tackle AS A SYSTEM and creates a potential failure point. What is a matter of judgement is whether this loss of strength of the system is acceptable or not. Everyone has to decide that for himself, but I think it's useful to have these discussions and highlight these issues, which not everyone has thought about.

Reading through the work done by your German “genius” (very interesting read) I noted that he suggested that when using a snubber, that the amount of slack chain left hanging after deployment should be the amount of stretch the snubber would provide – hence at maximum stretch you would be transferring load to the chain prior to breaking the snubber line. (He also stated that one should always use a snubber...)

I found his writing very interesting and something I've never done but something I'm definitely going to think about and see how easily it is to employ. At first blush, doesn't seem that easy. I'd have to mark out my snubber line so that I know quite precisely how many feet of snubber line I have out, I'd have to be able to then measure quite precisely how many more feet of chain I let out to meet that requirement. And I'd have to know fairly precisely how much stretch my snubber line has. All of those things together make it seem like this would not be an easy thing to deploy with accuracy...

Originally Posted by Dockhead

What's also true and possibly a defect in my system is that if a snubber breaks and you get a snatch load on a hard attachment like my stainless chain belaying strop, or someone's chain lock, that could break things and create a failure point.

Snatch loads can be enormous...

Originally Posted by Dockhead

Surprisingly we didn't seem to come anywhere near any kind of snatching up of the chain or any shock loading. Ride was smooth as it could be. I always use a snubber if there is a material chance of winds over 25 knots and/or wave action. I might loosen that rule now a bit. Certainly nothing under 30 knots is going to require a snubber.

IIRC, you are using ½ inch chain? In any case it's quite heavy chain. I would be very interested in learning more and seeing if indeed there is a cut-off for chains under a certain size or over a certain size for a given boat where this works and under what conditions one needs to use a snubber, then proper sizing the whole package.

The difficulty for using large chain, is that you can't carry as much chain. So it seems to me it depends upon where you are cruising and anchoring what is preferred, the compromises of a long snubber and a lot of chain, or less chain but sufficient where one is anchoring.

I have friends that have gone to smaller higher strength chain in order to have sufficient scope for where they are anchoring. In my opinion, having the correct scope is one of the most important parts of setting anchor. If you don't have enough scope – you have a much more serious problem than use or not of a snubber....

dj

[Dockhead]

Originally Posted by dlj

. . . IIRC, you are using ½ inch chain? In any case it's quite heavy chain. I would be very interested in learning more and seeing if indeed there is a cut-off for chains under a certain size or over a certain size for a given boat where this works and under what conditions one needs to use a snubber, then proper sizing the whole package.

That's why I thought of the German guy -- there are complicated physics involved way above my pay grade. But yes -- 1/2" chain behaves totally different -- in my experience -- from smaller grades.

Originally Posted by dlj

. . . The difficulty for using large chain, is that you can't carry as much chain. So it seems to me it depends upon where you are cruising and anchoring what is preferred, the compromises of a long snubber and a lot of chain, or less chain but sufficient where one is anchoring.

My cruising grounds the last 10 years have been the old Viking seaways including the whole Baltic Sea, whole North Sea, Iceland, Greenland. In a lot of these places you have to anchor in very deep water, so I can't compromise on the quantity of chain. I carry 100 meters (330 feet) of 1/2" chain, which has mostly been enough for me. I only wished for more in Greenland where there are very few feasible anchorages due to extremely steep sloping seabed, and I had to anchor in 30 meters and sometimes over 40 meters of water.


I think if I go back there I would extend the chain with rope; I don't think there's much point in having more than 100 meters of chain, even if it's a lighter grade.

Originally Posted by dlj

I have friends that have gone to smaller higher strength chain in order to have sufficient scope for where they are anchoring. In my opinion, having the correct scope is one of the most important parts of setting anchor. If you don't have enough scope – you have a much more serious problem than use or not of a snubber....

That's Dashew's recommendation -- to go to lighter but higher grade chain. His argument is that catenary does end at some point, and then at that moment when you most need it, so it's better to put the weight into the anchor.


I considered doing this myself but in the end I just didn't want to give up the plush ride of heavy chain. I removed all my chain from the boat a few times for racing, and noticed zero difference in upwind performance or trim, and that settled it -- I bought a new 1/2" chain in the end and kept the old gypsy.


Dashew also recommends not fetishizing scope, and himself anchors often on very short scope, sometimes less than 3:1. In deep water you need less scope (don't ask me why; the physics are beyond me), so he prefers to anchor in deep water on short scope. Obviously you need a good anchor (Dashew favors giant anchors) and good anchoring technique to pull this off, but I myself went through a serious storm in Greenland on about 2.5:1. It was over 40 meters of water and I only had 100m of chain. We held perfectly, which was a good thing because there are no rescue services up there and my insurance was not valid above latitude 69N.



Why I did this was because with very steep sloping seabed, the only chance you get for a place where your anchor might hold is in the deepest part of a cove, where the sediment rolls down. So you have no choice. Dashew teaches that it's better to be on shorter scope but deeper water and better seabed, than compromise on seabed, especially if it slopes.


Our German friend gives us pretty exact numbers for the increase in holding power with scope. Compare that to the difference in holding power with different seabeds, and you will see that you will prefer to compromise on scope, rather than on seabed quality, where the differences in holding power go to orders of magnitude.