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DoubleWhisky · 18-05-2014, 04:32

I read the BiB 2 thread with much of interest and want to thank all the contributors, particularly JonJo and Andrew Troup, for broadening my knowledge and understanding.
Still I’m under impression that the debate there was quite academical, and did not provide purely practical answers.
First of all my feeling is that for average cruising yacht the weight of a chain is not so much of an issue. May be for cruiser-racers used for cruising… With oversized stern sections and quite tiny forward sections they probably seriously need to limit weight at the bow. May be also for multihulls, as they are overly weight sensitive? Surely it is not a problem for flat out racers, as they do not use all chain rode anyway…
And for average mono hulled cruiser? One or two sizes of chain one way or another shouldn’t be a real problem, I believe, as long as other weight distribution is cared for properly. I know that concentrating the weight on the yacht have its advantages, but reading of Marchaj’s "Theory of sailing" and "Seaworthiness – the forgotten factor" left me under the impression, that this is more important for racing yachts and that it should be debated taking into account the longitudinal distribution of buoyancy (displacement) on the given hull. This distribution is much more even for cruising (even modern) yachts, than for cruisers-racers, so concentration of weight can be of less concern on cruisers. Generally the weight concentration is mainly addressed at the design level, by proper placement of ballast, engine, machinery, tankage and storage spaces. By the way – with the hull of more even distribution of buoyancy it is possible to overly concentrate the weights, leading to excessive pitching of the boat in a seaway.
Some people here are great fans of lightweight anchor chains, others, quite the contrary – put their trust into rather heavy chains. There are different reasonings behind these attitudes. Personally I do not want to have too light chain on my boat. I want the chain of given length (to have enough scope) and given weight (for catenary security and comfort). I'm not a fan of snubbers and use them rarely, as I prefer to rely on catenary.
But for all of us – light weight, medium weight or heavy weight camp – there is really one important question: what chain is the safest for given weight? What is the best compromise regarding static and dynamic loads. What chain is most fail safe?
I think it is very practical matter well worth a discussion here.

With my very best regards

Tomasz

MarkJ · 18-05-2014, 04:56

Ummmm your post is extremely academic. Why cant you just ask a question? You will just get the pontificator academics replying.

If you want to know the practical answer its not going to help you pitching the question as you have.

Why dont you tell us SIMPLY what boat you have and whats its displacement and those who KNOW this stuff in practice will make their suggestions. Pretty damn accurately.

Mark <----- who sails and is at anchor every night.

DoubleWhisky · 18-05-2014, 05:40

You see Mark, I know very well what size of chain I want to have on my boat. I have this size chain in the chain locker. But earlier or later I will be replacing it (by the same size chain, by the way).
While reading the BiB 2 thread I realized however, I'm not sure what material is best for the anchor chain, what material offers most security per unit of weight for this application

So I hope for academic seminar with some practical outcome

**boatman61** · 18-05-2014, 05:49

For me... the biggest galvanised I can fit on my anchor.. and in my windlass if I have one..
But then I'm a Luddite.. 3.5 x length + depth.. more weight on the bottom = more force needed to move the boat before the hook takes the strain = more security..
Guess someone can translate that to 'Scope'/'Catenary' and such.. then tell me I'm talking crap..

DoubleWhisky · 18-05-2014, 06:03

Quote:

Originally Posted by boatman61

For me... the biggest galvanised I can fit on my anchor.. and in my windlass if I have one..
But then I'm a Luddite.. 3.5 x length + depth.. more weight on the bottom = more force needed to move the boat before the hook takes the strain = more security..
Guess someone can translate that to 'Scope'/'Catenary' and such.. then tell me I'm talking crap..

So we are both Luddities, Boatie, as I have what fit in my windlass

Now I want to know what the best material is...

FSMike · 18-05-2014, 07:41

Quote:

Originally Posted by boatman61

-----
But then I'm a Luddite.. 3.5 x length + depth.. more weight on the bottom = more force needed to move the boat before the hook takes the strain = more security..
Guess someone can translate that to 'Scope'/'Catenary' and such.. then tell me I'm talking crap..

Boatie - Do I understand correctly that you deploy anchor chain to the length of 3.5 x your boat length? Plus the depth?
I'm sure you don't have much of a problem with dragging anchor.
For my 40' trimaran, which is rarely anchored in more than 10' of water, it seems a tad excessive. To each their own.

poiu · 18-05-2014, 13:23

I'd go with the Maggi grade 70. When I change, it will be the size down. If you want a heavy one they will do it, but with greater strength than a Campbell or Acco or whatever in G40 and if you want to save weight then you can achieve that aim, but keep the same strength by taking advantage of its higher tensile strength. This is the only one I have come across galvanised in stock in 70 grade.

They don't publish the chain's elastic modulus, but from the curves in the catalogue it doesn't look a lot different in shape from lower grade chain, so presumably not any more brittle.

I know you didn't talk about catenary and don't want a snubber, but anyway it does go with the selection of chain... If a lighter chain is chosen and a snubber is used I expect the same shock absorption could be achieved that you would have previously had from the catenary of the heavy chain. You may find the snubbing effect of the catenary of a smaller chain is adequate for your boat without a snubber anyway.

Another advantage of going for the size down is it puts less load on your anchor and chain. The catenary is an extra load on the anchor and chain that you remove completely in proportion to the saving in chain weight if you go for a snubber / lighter chain combination.

Actually, I'd really like to go for a titanium chain. I don't know anyone who sells it. I'm sure it would be too expensive, though with the way prices are falling it should be affordable in time.

**boatman61** · 18-05-2014, 13:34

Quote:

Originally Posted by FSMike

Boatie - Do I understand correctly that you deploy anchor chain to the length of 3.5 x your boat length? Plus the depth?
I'm sure you don't have much of a problem with dragging anchor.
For my 40' trimaran, which is rarely anchored in more than 10' of water, it seems a tad excessive. To each their own.

Most times I'm in around 4-5 metres.. so on my Corribee21 it would be roughly 21metres + depth.. on my 331 it was around 45metres + depth.. takes a lot to make me drag.. or make the anchor reset..

DoubleWhisky · 18-05-2014, 13:45

Quote:

Originally Posted by poiu

Actually, I'd really like to go for a titanium chain. I don't know anyone who sells it. I'm sure it would be too expensive, though with the way prices are falling it should be affordable in time.

I'm not so sure about future affordability of titanium. It is so expensive not only due the technology (this factor is decreasing really with the time going), but also due to the high cost of raw material. So the falling of the prices can stop at still unaffordable (unreasonable for this application) level.

Cheers

Tomasz

**Dockhead** · 18-05-2014, 15:10

You can get an in-depth technical explanation from Andrew Troup, in favor of larger, heavier, lower-grade chain. The simple, non-technical version -- from me -- is that you don't want something like anchor chain to be over-engineered and designed to work at the ragged edge of its capability. You want your anchor chain to have plenty of material so that as it corrodes and wears it still has plenty of material left. You want to be able to regalvanize it. You want it to be heavy and forgiving. And yes, catenary, even if it doesn't do anything in extreme conditions, does a lot in all other conditions.

For these reasons, I went with 12mm G40 chain rather than the lighter, G70 chain recommended by Steve Dashew.

100 meters of that weights 330kg. Does that hurt sailing performance, right in the bows? Yes, I think it can't be good. But I wouldn't feel quite safe with lighter chain.

That's an entirely unscientific view.

sparrowhawk1 · 19-05-2014, 01:07

Here's my 2 cents. not using a snubber is a big mistake. I've been anchoring for over 20 years have gone through some storms of over a hundred knots, in those conditions the chain is bar tight and every wave puts the total stress on the anchor and ground tackle without a snubber. I have a 40 foot boat with three eighths inch high test chain and a windlass to match. When I'm traveling I use a large Bruce usually put out at least 100 feet of chain with a snubber. if I'm going to stay for a long time I put out 2 fortresses hundred eighty degrees apart with 60 feet of 3/8 inch chain and a hundred feet of 3/4 line. I don't store heavy things forward of the mast. My system may seem overkill but I've been a lot of places were the holding isn't that great. And the safety of my vessel is dependent on the ground tackle so I'm going to use the best I can

Blue Crab · 19-05-2014, 02:20

So SH and others who normally anchor in sand, oolite, and grass ... You are laying out chain every night?

sparrowhawk1 · 19-05-2014, 04:31

If I'm on 1 anchor and the waters not deep I always use all chain rode. If the water is not clear you never know what's down there. shopping carts, bicycles, broken glass,etc. If I needed more than 125 feet of chain I would then have the rest of the rode line.( but only put out enough so it stays off the bottom) If I was somewhere where the water was clear and I could see there were no obstructions I would consider using 50 feet of chain and the rest of the rode line. Edit I have 100 feet of five eighths inch line connected to my 125 feet of chain. If a severe storm comes up and I have the room I can let out the line