Conachair
Guest
I think he generally steers clear of going too much into generalizing on anchor sizing or design. Wise man
Great site though. 
http://alain.fraysse.free.fr/sail/rode/rode.htm
Anchors, is one big one better than 2 small ones
- Thread starter Neeves
- Start date
I think he generally steers clear of going too much into generalizing on anchor sizing or design. Wise man
Great site though. http://alain.fraysse.free.fr/sail/rode/rode.htm
Neeves
Well-Known Member
Is this the same Conachair?
Frankly I fail to see what world girdling has to do with it, a Force 10 is the same in Ardnamurchan as Patagonia or Labrador.
Force 9 and 10 winds are not uncommon in the UK and it can be challenging to sail NW Scotland. Its patronising to suggest it cannot be as tough in the UK as many other places. Many comments on tough anchoring conditions came from a world girdling yachtsmen quoting summer conditions in the Med, bullets coming down into anchorages, sudden and 50-70kn micro bursts. He mentioned if someone anchored upwind of him, in the Med in summer, with a 'recommended' sized anchor - he was very twitchy.
But I'm glad to see that you consider someone making a summer cruise to the Outer Isles can feel comfortable with the recommended sized (new gen?) anchor (hopefully with a back up (or 2). My thoughts exactly.
Jonathan
Conachair
Guest
You are missing the point. You seem to think that there is a consensus to go 2 sizes up. That just doesn't seem to exist outside of long distance cruisers , not on forums and not around marinas. The "everyone wants 2 sizes up" seems to exist just in your head.
Neeves
Well-Known Member
Hi Conachair,
I'd link you to a poll, I appreciate terribly inaccurate, trying to define the 'bigness' of anchors carried. 30% carry recommended or lighter anchors, roughly 35% carry anchors one size bigger and 35% carry 2 sizes bigger. That's a fair number who believe in BIB and frankly I do not believe all of them are world girdling yacht owners - or not from the personal details they list. So there is, apparently, a wide body of opinion as expressed on CF believing in BIB, not a concensus but large none the less.
Actually I do not think there is a concensus, I think BIB, or 2 sizes bigger, is unnecessary, I do not believe all world girdling yacht owners believe it either. I think there are many world girdling yachtsmen surviving quite happily with pretty average sized CQRs - and if you recall I quoted a short list of award winning blue water cruisers (on CF), listed in the recent YM, as examples of people making pretty impressive voyages and relying on CQRs, Sunstone comes to mind and a couple of yachts making the NW passage. The thread here was to try to ascertain views of people in the UK whose waters can be as challenging as most other parts of the world, I know because I lived in Scotland for 25 years.
The most interesting aspect has been the apparent lack of market penetration of people owning new gen anchors.
Jonathan
I'd link you to a poll, I appreciate terribly inaccurate, trying to define the 'bigness' of anchors carried. 30% carry recommended or lighter anchors, roughly 35% carry anchors one size bigger and 35% carry 2 sizes bigger. That's a fair number who believe in BIB and frankly I do not believe all of them are world girdling yacht owners - or not from the personal details they list. So there is, apparently, a wide body of opinion as expressed on CF believing in BIB, not a concensus but large none the less.
Actually I do not think there is a concensus, I think BIB, or 2 sizes bigger, is unnecessary, I do not believe all world girdling yacht owners believe it either. I think there are many world girdling yachtsmen surviving quite happily with pretty average sized CQRs - and if you recall I quoted a short list of award winning blue water cruisers (on CF), listed in the recent YM, as examples of people making pretty impressive voyages and relying on CQRs, Sunstone comes to mind and a couple of yachts making the NW passage. The thread here was to try to ascertain views of people in the UK whose waters can be as challenging as most other parts of the world, I know because I lived in Scotland for 25 years.
The most interesting aspect has been the apparent lack of market penetration of people owning new gen anchors.
Jonathan
NormanS
Well-Known Member
I'm still not entirely sure what the OP is driving at, except that someone has obviously said to him that his anchor(s) is/are too small.
I'm happy that with a similar length monohull, with therefore much less windage than his cat, all of my anchors, and all of my chains, are more substantial than his. I can sleep at night
I'm happy that with a similar length monohull, with therefore much less windage than his cat, all of my anchors, and all of my chains, are more substantial than his. I can sleep at night
charles_reed
Well-Known Member
What are grandiosely termed "new generation" anchors was, IMHO, entirely a marketing ploy.
Alain Fraysse was quite specific (certainly in all the communication I had with him) about the principles on which he worked.
The first, of maximising fluke area to achieve holding power, is self evident - perhaps more controversial were the means by which he obtained the second benefit - penetration.
All I would point out that we had a bidding war by the various protagonists of these "new", highly overpriced anchors claiming their anchors could be, because of their superior design, be lighter and, therefore, cheaper than their competitors.
What is quite significant is that the manufacturers' recommendation are almost always the next size down from the boat-builders' supply.
Certainly the 25lb CQR (since I took steps to overcome certain inherent waywardness of my boat), provided by the builder holds significantly better than the 5kg Delta as recommended by S W Marine Factors.
In the final analysis human frailty must enter the equation - my age means that a 35kg CQR on 8mm chain would be a major challenge to handle (and I don't just mean to just raise it).
Alain Fraysse was quite specific (certainly in all the communication I had with him) about the principles on which he worked.
The first, of maximising fluke area to achieve holding power, is self evident - perhaps more controversial were the means by which he obtained the second benefit - penetration.
All I would point out that we had a bidding war by the various protagonists of these "new", highly overpriced anchors claiming their anchors could be, because of their superior design, be lighter and, therefore, cheaper than their competitors.
What is quite significant is that the manufacturers' recommendation are almost always the next size down from the boat-builders' supply.
Certainly the 25lb CQR (since I took steps to overcome certain inherent waywardness of my boat), provided by the builder holds significantly better than the 5kg Delta as recommended by S W Marine Factors.
In the final analysis human frailty must enter the equation - my age means that a 35kg CQR on 8mm chain would be a major challenge to handle (and I don't just mean to just raise it).
oldbilbo
...
I don't attribute the 'BIB' idea to Alain Fraysse but agree with Conachair and others that AF's site is a lode of sense and sound info. For my own part, my reading - applied to my comparatively-limited experience - persuades me to have on board an anchoring setup that is certainly strong enough for any reasonably-predictable task I might ask of it. I want a 'modern generation' primary anchor that reportedly performs considerably better than the 'adequate' 25lb CQR I have, and among several excellent contenders I have at present a preference for the Kobra 2.
Selection of size/weight is at issue here. I know of one sailor who anchors muchly in the Scottish NW, and who reports a satisfactory outcome in Lochmaddy using a 16kg Delta in an F9, from his 30' boat ( http://www.yotblog.com/avilion/2011/09/27/2005-summer-cruise/ ). The Delta Selection Guide above suggest a 10kg model for that size of boat, so certainly this experienced and canny sailor has gone for a substantially-heavier/larger hook - and has reaped the benefit. The Etap 30 is a larger boat than mine, and heavier by about 0.6 ton.
Below is a Selection Guide for the Kobra 2 product.
It would appear that an 8kg model should suffice. I'm not persuaded. The 12kg model seems to me to be about right, but the 14kg - providing a worthwhile increase in holding power over the '10' - is only a fiver more expensive. The 16kg model starts to look like overkill, is £30 dearer than the '10', and is likely to be harder for me to store and handle on the foredeck. I believe I'll go for the 14kg Kobra 2..... to be matched with the 50m. of 10mm chain and 50m. of 18mm nylon 8-plait I already have. That seems to me to be enough.....
The existing 25lb CQR, with its existing 8mm chain and 12mm 8-plait warp, will be relegated to the No2 slot. Now, if someone offered me a reasonable price for this, I'd replace it with one of Bainbridge's new 12kg D-shape types.
Selection of size/weight is at issue here. I know of one sailor who anchors muchly in the Scottish NW, and who reports a satisfactory outcome in Lochmaddy using a 16kg Delta in an F9, from his 30' boat ( http://www.yotblog.com/avilion/2011/09/27/2005-summer-cruise/ ). The Delta Selection Guide above suggest a 10kg model for that size of boat, so certainly this experienced and canny sailor has gone for a substantially-heavier/larger hook - and has reaped the benefit. The Etap 30 is a larger boat than mine, and heavier by about 0.6 ton.
Below is a Selection Guide for the Kobra 2 product.
It would appear that an 8kg model should suffice. I'm not persuaded. The 12kg model seems to me to be about right, but the 14kg - providing a worthwhile increase in holding power over the '10' - is only a fiver more expensive. The 16kg model starts to look like overkill, is £30 dearer than the '10', and is likely to be harder for me to store and handle on the foredeck. I believe I'll go for the 14kg Kobra 2..... to be matched with the 50m. of 10mm chain and 50m. of 18mm nylon 8-plait I already have. That seems to me to be enough.....
The existing 25lb CQR, with its existing 8mm chain and 12mm 8-plait warp, will be relegated to the No2 slot. Now, if someone offered me a reasonable price for this, I'd replace it with one of Bainbridge's new 12kg D-shape types.
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Conachair
Guest
Almost with you there.
On the other hand when sailors with the massive wealth of experience of the likes of Evans or Dashew et al speak I will most definitely listen. My limited experience of a few years round the atlantic left a lot of respect for a 1 size too big rocna, never needed anything else. There's something attention grabbing about water exploding from a nylon snubber going bar tight as the bow slews round after sailing 100m across an anchorage with a 50Kt gust 180 deg from the last one. It situations like that 2 hooks would be a complete tangled disaster.
Is 2 sizes up overkill for bluewater cruising? Quite possibly but if the funds were there I wouldn't hesitate. Where's the down side?
As for a decent sized anchor Vs 2 smaller ones? I've never needed to play with 2 anchors, no doubt there are situations where it makes a lot of sense but most situations, give me a decent size new gen with a load of scope.
Neeves
Well-Known Member
Dashew was referring to old styles and Evan has gone back to a Bruce. The thesis is on the basis of newer designed anchors. When the winds are as you describe, simply drop an anchor off the bow such that it just drags across the seabed. It will tame the yawing, if the bottom is such this is not possible try a strong bucket. Its certainly better than allowing your yacht to be beaten from piller to post. If you have a cat get closer to the shore and tie a stern line to a tree. But to allow your yacht to 'sail' 100m looks questionable and is not an argument for bigger anchors, just an argument for using your imagination. You might need a 2 sizes bigger anchor because you impose such a huge load on your anchor, even a 10t yacht sailing 100m after a 50knot gust must have some momentum - much better to tame the movement in the first place (that way you get a decent nights sleep). Its the snatch loads that cause the problem, tame them and many of the issues disappear.
There are many techniques, 2 anchors under some conditions, one anchor and the other off the bow, a stern line ashore, 'V' sail. But to allow your yacht free reign is not one of them (unless of course you need rely on one big, over big, anchor and enjoy snatch loads such that the water' shoots' out of your snubbers).
Oldbilbo - before you buy your Kobra I might, in your case, ask Plastimo for the quality of the steel used in the shank. If you thought a well known anchor maker using some questionable steel compromised the safety performance of their anchor then I might query what Plastimo use (if you thought that furore was simply a storm in a teacup - then carry on). If they do not know or will not tell you, the steel quality, I might think as to why you should buy a product with no specification. If they say the steel is adequate, I might supplementarily wonder what adequate means. It has great performance as an anchor in most tests, I like the simplicity and success of the design, but will it perform as well under Conachair's yawing scenario where the load might be taken on the shank at 90 degrees. If you get an answer from Plastimo I think people might be interested. You could buy one 2, or 3, sizes bigger (it will be stronger) but do you need to (and will, even at 2 sizes bigger, it be strong enough) The Kobra is cheap for a reason.
Jonathan
There are many techniques, 2 anchors under some conditions, one anchor and the other off the bow, a stern line ashore, 'V' sail. But to allow your yacht free reign is not one of them (unless of course you need rely on one big, over big, anchor and enjoy snatch loads such that the water' shoots' out of your snubbers).
Oldbilbo - before you buy your Kobra I might, in your case, ask Plastimo for the quality of the steel used in the shank. If you thought a well known anchor maker using some questionable steel compromised the safety performance of their anchor then I might query what Plastimo use (if you thought that furore was simply a storm in a teacup - then carry on). If they do not know or will not tell you, the steel quality, I might think as to why you should buy a product with no specification. If they say the steel is adequate, I might supplementarily wonder what adequate means. It has great performance as an anchor in most tests, I like the simplicity and success of the design, but will it perform as well under Conachair's yawing scenario where the load might be taken on the shank at 90 degrees. If you get an answer from Plastimo I think people might be interested. You could buy one 2, or 3, sizes bigger (it will be stronger) but do you need to (and will, even at 2 sizes bigger, it be strong enough) The Kobra is cheap for a reason.
Jonathan
GrahamM376
Well-Known Member
My own experience with 38ft 9 ton boat has been that we used to drag the 35lb harbourfast (CQR lookalike) regularly so, if it was blowing a bit or wind over tide snatching, we used to shackle the Fortress to it and lay them in tandem. Then changed to a 44lb Manson Supreme and haven't dragged it so far. Can't see the point of two small anchors as they would rarely pull together, the load would be on one at a time.
Neeves
Well-Known Member
Hi Graham,
Your anchor looks about the right size, but obviously have no idea of your windage. Its not suggested 2 small anchors. Its suggested your anchor might be too small, you should go to, say, 35kg. My contention is you are about right but I'd be carrying a second anchor, same weight, 20kg, different style, as back up to deploy if necessary (but certainly not ungrading in size). 2 anchors can stop veering (if the wind is varying through 90 degrees or less and blowing 30 knots or more)- its a useful part of the armoury - it does work, its easy to do.
Jonathan
Your anchor looks about the right size, but obviously have no idea of your windage. Its not suggested 2 small anchors. Its suggested your anchor might be too small, you should go to, say, 35kg. My contention is you are about right but I'd be carrying a second anchor, same weight, 20kg, different style, as back up to deploy if necessary (but certainly not ungrading in size). 2 anchors can stop veering (if the wind is varying through 90 degrees or less and blowing 30 knots or more)- its a useful part of the armoury - it does work, its easy to do.
Jonathan
Uricanejack
Well-Known Member
Hmm somebody might actually know what he is talking about.
Its the catenary which counts.
GrahamM376
Well-Known Member
We still carry the Fortress, Harbourfast and a couple of fisherman's as well. Fortress makes excellent kedge and main backup.
Babylon
Well-Known Member
Sorry to add a bit of 'practical decision-making' to this theoretical debate, but from the perspective of a South Coast sailor increasingly spending his summers cruising Brittany, Scotland, Ireland, etc in a 27ft 5ton monohull - rather than heading off for perpetual blue-water sailing...
I replaced as my main bower anchor the old 25lb CQR (30m of 8mm chain and 50m of anchorplait no windlass) with a 25lb Manson (50m of 8mm chain and 50m of 3-strand plus a windlass), keeping the old anchor and cable as a spare.
I considered going up a size for the Manson, but rejected this for these reasons:
* The heavier, larger anchor overwhelmed the relatively small area around the bow, and proved to be back-breaking to manhandle over the roller etc;
* The effectiveness of the anchor seems to me to be based more on the weight of the chain and the length of catenary rather than on the anchor's absolute size;
* If a serious blow was forecast (how often in European coastal waters is one without a wide range of sources of 24-hour forecasts?!), then I should have time to deploy the spare bower in a V-formation or even a tandem-formation (I'm also considering making up a V-shaped riding-sail);
* The retention of the second anchor of similar overall weight enables me to set up a Bahamian moor if I had to leave the boat for a while;
* In the event that my main Manson bower becomes fouled, I am in the happy position of being able to buoy it, whilst still having a perfectly workable CQR with which to re-anchor elsewhere.
So, I'm in the two smaller anchors camp - plus I carry a lighter Fortress (10m of 8mm and 50m of 3-strand) as a kedge.
(NB: My decision to buy a new-generation Manson, rather than say a less expensive Kobra or Delta, is based on the perfectly-convincing to me aspects of its design - eg the roll-bar, fluke design, etc - and the widely-reported evidence of its effectiveness in a range of seabeds, relative to the older designs, especially as I've often dragged the old CQR on weedy bottoms etc. This personal choice of anchor type is subsidiary to the main question of the thread, and I'm not looking to start WW3!)
I replaced as my main bower anchor the old 25lb CQR (30m of 8mm chain and 50m of anchorplait no windlass) with a 25lb Manson (50m of 8mm chain and 50m of 3-strand plus a windlass), keeping the old anchor and cable as a spare.
I considered going up a size for the Manson, but rejected this for these reasons:
* The heavier, larger anchor overwhelmed the relatively small area around the bow, and proved to be back-breaking to manhandle over the roller etc;
* The effectiveness of the anchor seems to me to be based more on the weight of the chain and the length of catenary rather than on the anchor's absolute size;
* If a serious blow was forecast (how often in European coastal waters is one without a wide range of sources of 24-hour forecasts?!), then I should have time to deploy the spare bower in a V-formation or even a tandem-formation (I'm also considering making up a V-shaped riding-sail);
* The retention of the second anchor of similar overall weight enables me to set up a Bahamian moor if I had to leave the boat for a while;
* In the event that my main Manson bower becomes fouled, I am in the happy position of being able to buoy it, whilst still having a perfectly workable CQR with which to re-anchor elsewhere.
So, I'm in the two smaller anchors camp - plus I carry a lighter Fortress (10m of 8mm and 50m of 3-strand) as a kedge.
(NB: My decision to buy a new-generation Manson, rather than say a less expensive Kobra or Delta, is based on the perfectly-convincing to me aspects of its design - eg the roll-bar, fluke design, etc - and the widely-reported evidence of its effectiveness in a range of seabeds, relative to the older designs, especially as I've often dragged the old CQR on weedy bottoms etc. This personal choice of anchor type is subsidiary to the main question of the thread, and I'm not looking to start WW3!)
vyv_cox
Well-Known Member
Read the Alain Fraysse website, which most authorities recognise as giving an accurate mathematical assessment of catenary and other anchoring forces. Above a wind strength of about force 6-7 catenary pretty much disappears as a useful device. The rode will not be straight of course as its own weight will always give it some curve, but the whole lot of it will be off the bottom. I have confirmed this by diving on my anchor in winds of around that strength many times, but particularly in Cala Lupe in Sardinia, where we were anchored in shallow water, 2 - 2.5 metres, with 35 metres of chain out. The whole length of it was off the bottom for large periods of time.
Neeves
Well-Known Member
KellysEye and Uricanejack.
You might both be correct but I have been in anchorages with forecast Storm force winds where there is simply not room to deploy 90m of chain and I have shared that same anchorage with 2 other yachts. I arrived second and I admit I could have deployed 90m, but any movement (of my anchor) I would have been on the shore. If I had deployed 90m there would have been no room for the third yacht. The anchorage is the only sensible one for 70nm to the east and maybe 50nm to the NW, there was nothing else. The anchorage is perfectly secure except the wind gusts down at 50-70knots at 180 degrees. The answer is not 90m of chain its 2 short chains, 2 good anchors and a line to shore, or one short chain (and a good anchor) and 2 lines to shore - for each of all 3 yachts. With this system we could have had 6 maybe 8 yachts snug in the anchorage.
We conducted an experiment 6m depth (height), 30m of 8mm chain, 5:1 scope. It takes 80kg to lift the chain off the bottom (in air) in water maybe 70kg. A decently fit man could lift 30m of chain at a 5:1 scope, your yacht on the move will load that chain with 70kg in around 25 knot of wind. Once the chain is off the bottom, yes the chain is not straight, but your yacht is free to move, accelerated by any gust and it can develop large loads on your anchor. Few people can carry 87m of chain (especially if its 10mm or 12mm) but it will lift of the bottom, especially once you get to greater depths, like 10m - 40 knots of wind is not unheard of, you need 2 things
a decent reliable anchor (preferably with an equivalent back up)
decent reliable snubber(s)
Snubbers will absorb the shock loads as long as they are long enough, think at least 10m of 10mm nylon (anything less will not have the elasticity - and if you have a larger yacht, go longer go greater diameter). Think of it as a bungy cord for your yacht. In fact extend the analogy - imagine jumping of a bridge with you ankles tied to chain, now imagine your ankles tied to elastic. The catenary of the chain straightens and as it straightens the chain become less and less useful and greater of an inelastic piece of steel (holding you to your anchor) - give it a better chance, think bungy. But think of securing the bit of steel firmly to the seabed - maybe a decent anchor.
HMS Ark Royal at anchor had an officer specifically responsible to check the position of the vessel - as she dragged back it was his decision when the anchor was lifted, she steamed forward, re-anchored and the procedure re-started. The RN knew of the advantage of chain but knowing they could not carry enough had an anchor watch. We are lucky we have anchor alarms, decent anchors and nylon to use as snubbers.
And for those that think new gen anchors drag try this:
http://www.spade-anchor.co.uk/sd_further_info2.htm
I claim no credit for pulling it from the archives but it does seem most apt. It was sent to me by a 'well wisher'
Jonathan
You might both be correct but I have been in anchorages with forecast Storm force winds where there is simply not room to deploy 90m of chain and I have shared that same anchorage with 2 other yachts. I arrived second and I admit I could have deployed 90m, but any movement (of my anchor) I would have been on the shore. If I had deployed 90m there would have been no room for the third yacht. The anchorage is the only sensible one for 70nm to the east and maybe 50nm to the NW, there was nothing else. The anchorage is perfectly secure except the wind gusts down at 50-70knots at 180 degrees. The answer is not 90m of chain its 2 short chains, 2 good anchors and a line to shore, or one short chain (and a good anchor) and 2 lines to shore - for each of all 3 yachts. With this system we could have had 6 maybe 8 yachts snug in the anchorage.
We conducted an experiment 6m depth (height), 30m of 8mm chain, 5:1 scope. It takes 80kg to lift the chain off the bottom (in air) in water maybe 70kg. A decently fit man could lift 30m of chain at a 5:1 scope, your yacht on the move will load that chain with 70kg in around 25 knot of wind. Once the chain is off the bottom, yes the chain is not straight, but your yacht is free to move, accelerated by any gust and it can develop large loads on your anchor. Few people can carry 87m of chain (especially if its 10mm or 12mm) but it will lift of the bottom, especially once you get to greater depths, like 10m - 40 knots of wind is not unheard of, you need 2 things
a decent reliable anchor (preferably with an equivalent back up)
decent reliable snubber(s)
Snubbers will absorb the shock loads as long as they are long enough, think at least 10m of 10mm nylon (anything less will not have the elasticity - and if you have a larger yacht, go longer go greater diameter). Think of it as a bungy cord for your yacht. In fact extend the analogy - imagine jumping of a bridge with you ankles tied to chain, now imagine your ankles tied to elastic. The catenary of the chain straightens and as it straightens the chain become less and less useful and greater of an inelastic piece of steel (holding you to your anchor) - give it a better chance, think bungy. But think of securing the bit of steel firmly to the seabed - maybe a decent anchor.
HMS Ark Royal at anchor had an officer specifically responsible to check the position of the vessel - as she dragged back it was his decision when the anchor was lifted, she steamed forward, re-anchored and the procedure re-started. The RN knew of the advantage of chain but knowing they could not carry enough had an anchor watch. We are lucky we have anchor alarms, decent anchors and nylon to use as snubbers.
And for those that think new gen anchors drag try this:
http://www.spade-anchor.co.uk/sd_further_info2.htm
I claim no credit for pulling it from the archives but it does seem most apt. It was sent to me by a 'well wisher'
Jonathan
vyv_cox
Well-Known Member
I gave a talk on anchoring last year, after which a member of the audience chatted to me about the topic. He was an ex deck officer on an aircraft carrier and told me that they always dragged. He confirmed what you say - an officer was always monitoring drag, making a decision as to when they had gone far enough and ordering re-anchoring.
oldbilbo
...
Good. That confirms the 'ordinary practice of seamen' that one should keep an anchor watch in other than benign conditions. For me, that is less than F5. In really strong winds, one would expect to have the engine available with which to take some of the load off in the gusts. As I wouldn't sleep easy, anchored in a F5 and above, I may as well be up and 'watching'.
As for....
....that's a rather different proposition to the original. 'Lines ashore and fixed securely to a sub-continent' changes the argument somewhat.
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cds8
New Member
Chris_Robb
Well-Known Member
Jonathan. For me, being a bit of a swinger
, I prefer one large anchor to take account of the change of wind. You however have what appears to be an entirely different set of circumstances as defined above. In the Med, anchored and stern to rocks, I would be happier with say 2 large anchors, but I would, for the simplicity of laying and leaving in an emergency, much prefer 1 single large one. I bought the recommended size for my boat which was 45LBS, but If I was buying again, I would buy at least one size up. I have no problems handling this one, so one might as well go bigger.
