By Dick - 24 Jan 2023
Hi all,
It is my take that weight in the anchor does more to enhance ground tackle effectiveness than weight anywhere else It is also my casual observation (in no way buttressed by facts or evidence I am aware of) that increasing weight in the anchor increases effectiveness in ground tackle effectiveness not linearly, but exponentially.
So, I had a new thought on how to think about weight in the anchor. Mine is a 77-pound Spade: used ~~10 years. My previous Spade was 66 pounds (used 8 years) making for an ~~17% weight increase which would be a nice linear increase in ground tackle effectiveness, but not dramatic. My experience (and this is the really casual observation) is that the 77 pounder is more than 17% more effective: it is exponentially better. I am not sure if there is anything in the literature to validate this (or otherwise).
I went with a bigger anchor as I anchor in marginal and remote areas. That said, even if you are not going to Greenland or the fjords of Norway, 10 extra pounds on the bow in your anchor will likely make little noticeable difference in sailing performance, but might make a difference in anchoring security.
Interested in reactions to my random thoughts.
My best, Dick Stevenson, s/v Alchemy
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By simoncurrin - 25 Jan 2023
Dick,
Yes, we have saved weight in the chain (moved to high tensile 10 years ago) and went for a 100 lbs anchor and have no regrets. It should be easy enough to measure whether the relationship is linear or exponential so the data must exist.
Simon
+xHi all, It is my take that weight in the anchor does more to enhance ground tackle effectiveness than weight anywhere else It is also my casual observation (in no way buttressed by facts or evidence I am aware of) that increasing weight in the anchor increases effectiveness in ground tackle effectiveness not linearly, but exponentially. So, I had a new thought on how to think about weight in the anchor. Mine is a 77-pound Spade: used ~~10 years. My previous Spade was 66 pounds (used 8 years) making for an ~~17% weight increase which would be a nice linear increase in ground tackle effectiveness, but not dramatic. My experience (and this is the really casual observation) is that the 77 pounder is more than 17% more effective: it is exponentially better. I am not sure if there is anything in the literature to validate this (or otherwise). I went with a bigger anchor as I anchor in marginal and remote areas. That said, even if you are not going to Greenland or the fjords of Norway, 10 extra pounds on the bow in your anchor will likely make little noticeable difference in sailing performance, but might make a difference in anchoring security. Interested in reactions to my random thoughts. My best, Dick Stevenson, s/v Alchemy
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By Dick - 25 Jan 2023
+xDick, Yes, we have saved weight in the chain (moved to high tensile 10 years ago) and went for a 100 lbs anchor and have no regrets. It should be easy enough to measure whether the relationship is linear or exponential so the data must exist. Simon +xHi all, It is my take that weight in the anchor does more to enhance ground tackle effectiveness than weight anywhere else It is also my casual observation (in no way buttressed by facts or evidence I am aware of) that increasing weight in the anchor increases effectiveness in ground tackle effectiveness not linearly, but exponentially. So, I had a new thought on how to think about weight in the anchor. Mine is a 77-pound Spade: used ~~10 years. My previous Spade was 66 pounds (used 8 years) making for an ~~17% weight increase which would be a nice linear increase in ground tackle effectiveness, but not dramatic. My experience (and this is the really casual observation) is that the 77 pounder is more than 17% more effective: it is exponentially better. I am not sure if there is anything in the literature to validate this (or otherwise). I went with a bigger anchor as I anchor in marginal and remote areas. That said, even if you are not going to Greenland or the fjords of Norway, 10 extra pounds on the bow in your anchor will likely make little noticeable difference in sailing performance, but might make a difference in anchoring security. Interested in reactions to my random thoughts. My best, Dick Stevenson, s/v Alchemy
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By Dick - 25 Jan 2023
+xDick, Yes, we have saved weight in the chain (moved to high tensile 10 years ago) and went for a 100 lbs anchor and have no regrets. It should be easy enough to measure whether the relationship is linear or exponential so the data must exist. Simon +xHi all, It is my take that weight in the anchor does more to enhance ground tackle effectiveness than weight anywhere else It is also my casual observation (in no way buttressed by facts or evidence I am aware of) that increasing weight in the anchor increases effectiveness in ground tackle effectiveness not linearly, but exponentially. So, I had a new thought on how to think about weight in the anchor. Mine is a 77-pound Spade: used ~~10 years. My previous Spade was 66 pounds (used 8 years) making for an ~~17% weight increase which would be a nice linear increase in ground tackle effectiveness, but not dramatic. My experience (and this is the really casual observation) is that the 77 pounder is more than 17% more effective: it is exponentially better. I am not sure if there is anything in the literature to validate this (or otherwise). I went with a bigger anchor as I anchor in marginal and remote areas. That said, even if you are not going to Greenland or the fjords of Norway, 10 extra pounds on the bow in your anchor will likely make little noticeable difference in sailing performance, but might make a difference in anchoring security. Interested in reactions to my random thoughts. My best, Dick Stevenson, s/v Alchemy
Hi Simon,
Yes, I think for a widely wandering and adventurous boat such as Shimshal, that is the way to go. Elsewhere in the Forum, I believe, I have posted my article on choosing chain where I make a case for choosing chain primarily for its strength, rather than weight, and that the catenary of chain disappears when you want it most: in a gale: so weight in chain is less or not at all important. This is when pounds added to the anchor makes a big difference. and makes for a far more effective ground tackle system.
Too many cruisers, in my observation and opinion, worry too much about weight in the bow or expense when choosing such an important, mission critical, piece of gear.
My best, Dick Stevenson, s/v Alchemy
Ps. Had dinner last night with Brian McVickers who is well and planning to crew on a boat doing an W to E NW passage in a year or two.
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By Sonia.Johal - 28 Jan 2023
Thanks Dick,
Would you share a link to your article when not too busy?
As you know I’m taking the cowards route and buying two Rocna anchors, while complying with manufacturer’s 50knot wind recommendations for insurance purposes.
My boat’s fully laden weight is 10T and I purchased the 20kg anchor. My secondary anchor only for emergency >force 10+ wind usage, will weigh less at 15kg.
My investigation provided this following data on boat length, boat weight, anchor weight and recommended chain;
For me this data seems to be subject to anchor design versus boat length and weight. So this data is a little too complex for me to determine the relationship as linear or exponential 🤔
Hope this helps with your anchor weight and chain review and looking forward to reading your updated article.
Grateful for your feedback and ongoing support.
Fair winds,
Sonia
SY Salacia
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By Sonia.Johal - 28 Jan 2023
P.S. my windlass design and capacity is also a major factor
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By Dick - 28 Jan 2023
+xP.S. my windlass design and capacity is also a major factor
Hi Sonia,
The article can be found at: https://stevedmarineconsulting.com/choosing-chain-challenging-a-maritime-myth/.
I am not sure what you mean by saying you are taking the coward’s way out?
Which version(s) of the Rocna anchor do you have 2 of?
And, yes, too often a windlass’s design or installation plays a part in anchor choice: almost invariably to the detriment of designing an effective ground tackle system.
I am not a fan of the charts used by anchor companies. In general, for widely wandering cruising boats, I have found 2 levels bigger than their recommendations about right.
I have written elsewhere in the Forum, I believe, on my thoughts on anchoring: in short, I think for widely wandering cruising boats one’s best anchor (sometimes stowed deep and called a storm anchor) should be one’s everyday anchor. Too often one meets gale and more force winds at zero-dark-thirty in an unexpected squall: not the time to be getting out a spare anchor. And there is little reason, none compelling for cruising boats, not to use one’s best anchor all the time with an adequate spare in the bilge.
And, like most things having to do with anchoring, documenting that anchor effectiveness increases exponentially rather than linearly with increased weight is elusive. That said: I am pretty sure that is the case.
My best, Dick Stevenson, s/v Alchemy
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By Sonia.Johal - 28 Jan 2023
Thanks Dick,
I appreciate the article and it was great to read about your own sailing adventures too…
Having now researched as much as I can, I have decided to revisit my windlass specification to see how much it can safely lift and with what size of G40 chain…
Although , I will not be upgrading my windlass, this will help me to determine whether or not I can accommodate a heavier Rocna 25kg anchor with its wider and heavier G40 chain requirements…
My spare anchor and chain will also be used to ensure I have a second seabed holding option, if I buy the heavier Rocna…
Grateful for your help and support.
Fair winds,
Sonia
SY Salacia
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By Dick - 28 Jan 2023
+xThanks Dick,I appreciate the article and it was great to read about your own sailing adventures too…Having now researched as much as I can, I have decided to revisit my windlass specification to see how much it can safely lift and with what size of G40 chain… Although , I will not be upgrading my windlass, this will help me to determine whether or not I can accommodate a heavier Rocna 25kg anchor with its wider and heavier G40 chain requirements…My spare anchor and chain will also be used to ensure I have a second seabed holding option, if I buy the heavier Rocna…Grateful for your help and support.Fair winds,SoniaSY Salacia
Hi Sonia,
Were I to start over, and money no object (always plays a role) I would go with high tensile (G10?) chain and put any weight savings into the anchor. Or, the weight savings might enable your present windlass to work effectively.
What design style Rocna are you choosing? Both anchors the same style?
As a point of reference: Alchemy has anchored (certainly many thousands of times dropping the anchor at this point) on the same 5/16” ACCO G4 chain for more than twenty years now: this on a 12m 30,000-pound boat: re-galvanized once. Loss of metal on the links still comes in within spec.
My best, Dick
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By Sonia.Johal - 28 Jan 2023
Thanks Dick,
My anchor is the original Rocna, as opposed to the newer Vulcan recommends.
I understand the G10 (100N/mm chain) will be lighter, and appreciate you know it to be enough, but I believe the G10 is also weaker.
Also, to satisfy my insurance I must comply with Rocna’s G40 (400N/mm chain) recommendation for upto 50knots and also to benefit from the manufacturer’s warranty.
I also feel some chandleries have stopped selling anything less than G40. For example, found this interesting information on the Jimmy Green website;
Many thanks again and I hope this Jimmy Green table helps… Alternatively I also found another useful article link;
https://www.elitesalesinc.com/tag/industrial-chain-grades/
Wishing you all the best with your upcoming article and thanks for keeping us Associate newbies on our toes...
Fair winds,
Sonia
SY Salacia
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By Dick - 28 Jan 2023
+xThanks Dick,My anchor is the original Rocna, as opposed to the newer Vulcan recommends. I understand the G10 (100N/mm chain) will be lighter, and appreciate you know it to be enough, but I believe the G10 is also weaker. Also, to satisfy my insurance I must comply with Rocna’s G40 (400N/mm chain) recommendation for upto 50knots and also to benefit from the manufacturer’s warranty.I also feel some chandleries have stopped selling anything less than G40. For example, found this interesting information on the Jimmy Green website; Many thanks again and I hope this Jimmy Green table helps… Alternatively I also found another useful article link; https://www.elitesalesinc.com/tag/industrial-chain-grades/Wishing you all the best with your upcoming article and thanks for keeping us Associate newbies on our toes...Fair winds,SoniaSY Salacia
Hi Sonia,
My apologies: senior moment.
G10 refers to fg sheeting. I should have written that the higher-level chain than G4 is Grade 70 (G70) which is both significantly lighter and stronger.. Chain for boats is well explained at: https://www.practical-sailor.com/sails-rigging-deckgear/anchoring-mooring/making-sense-of-marine-chain-standards.
My best, Dick
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By Sonia.Johal - 30 Jan 2023
Thanks Dick,
I feel we all have them at all ages ☺️. I’m grateful for your article, especially as I subscribe and very much enjoy Practical Sailor magazine.
Unfortunately, I must comply with manufacturer’s guidelines for my insurance company and will be sticking with my G40. Although I will re-visit my anchor options…
Thanks again for your input.
Fair winds,
Sonia
SY Salacia
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By Dick - 31 Jan 2023
+xThanks Dick,I feel we all have them at all ages ☺️. I’m grateful for your article, especially as I subscribe and very much enjoy Practical Sailor magazine.Unfortunately, I must comply with manufacturer’s guidelines for my insurance company and will be sticking with my G40. Although I will re-visit my anchor options…Thanks again for your input.Fair winds,SoniaSY Salacia
Hi Sonia,
Firstly, sticking with G4 chain is eminently seamanlike and is a very good (and very common) choice for many cruisers: I just mention grade 70 as way some experienced skippers have saved weight in the chain and put weight in the anchor. This enhances the effectiveness of their ground tackle system. As grade70 chain is more expensive and presents some challenges at retaining overall strength when choosing shackles to attach to the anchor, it is far from commonly seen (often solved by specifying the end links being over-sized). I am also thinking others are likely to read this stream and may wish to consider their options.
I have not heard of manufacturers giving guidelines that the insurance company (and boat owner) feels must be complied with. Is this common? What are other’s experiences in this area? My experience is that the insurance company wants periodic surveys and if the surveyor signs off saying the boat is fit for purpose, then that covers the Insurance Company and they stay away from the details.
It would not make me happy to hear manufacturers and/or ins co giving guidelines to skippers. I have not always been happy with decisions by either party. For example, look at the number of boats out there with stainless steel chain: I assume most or all of these boats are insured and many came with the chain from the manufacturers. And ss chain has a long history of rare but occasional catastrophic failure (crevice corrosion) (I believe the QC on ss chain has improved a good deal over the last years so that buying ss chain from a good source makes less likely problems).
And finally, from my perspective over the decades, I would consider properly installed grade 70 chain to be seamanlike (safe and effective) and in no way in need condemnation by manufacturers and or insurance companies.
As I have no personal experience with Grade 70 chain, I look forward to hearing other’s reports.
My best, Dick Stevenson, s/v Alchemy
Ps. You report re-visiting anchor options: just a heads-up. There is accumulating evidence that the classic Rocna with the roll bar has an occasional bad habit of not re-setting in a wind shift or in tidal current changes in direction.
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By Sonia.Johal - 31 Jan 2023
Thanks Dick,
Please note it’s the G40 that has been recommended to me by the Rocna specifications, plus chandleries such as Jimmy Green also recommend G40 as their minimum recommended chain.
Plus, I may confirm that subject to manufacturer specifications compliance the Rocna anchor is deemed to be sufficient up to 50knots or F10 of wind.
I take onboard your caution, but my own experience has been very different with continuous live-aboard usage since 2016. With changing current directions and backing or veering winds exceeding F8, I have not yet experienced any drag, nor any twist or fowling. In fact the Rocna has yet to budge according to both my chart plotter and iPad.
As my journey has taken me from the Shetlands, Scotland Ireland and Wales to and around the Outer Hebrides, the Channel Islands and English South Coast on a frequent basis, I am fully satisfied with my original Rocna anchor’s holding.
Of all the articles read, I am yet to be convinced, as many refer to smaller vessels in shallow water.
Plus, I don’t intend to use my Rocna beyond its manufacturing specifications.
Grateful for your input and guidance.
Fair winds,
Sonia
SY Salacia
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By Dick - 2 Feb 2023
+xThanks Dick,Please note it’s the G40 that has been recommended to me by the Rocna specifications, plus chandleries such as Jimmy Green also recommend G40 as their minimum recommended chain.Plus, I may confirm that subject to manufacturer specifications compliance the Rocna anchor is deemed to be sufficient up to 50knots or F10 of wind.I take onboard your caution, but my own experience has been very different with continuous live-aboard usage since 2016. With changing current directions and backing or veering winds exceeding F8, I have not yet experienced any drag, nor any twist or fowling. In fact the Rocna has yet to budge according to both my chart plotter and iPad.As my journey has taken me from the Shetlands, Scotland Ireland and Wales to and around the Outer Hebrides, the Channel Islands and English South Coast on a frequent basis, I am fully satisfied with my original Rocna anchor’s holding. Of all the articles read, I am yet to be convinced, as many refer to smaller vessels in shallow water.Plus, I don’t intend to use my Rocna beyond its manufacturing specifications.Grateful for your input and guidance.Fair winds,SoniaSY Salacia
Hi Sonia,
I am glad you have had good luck with your classic Rocna with a roll bar. It is a much better anchor than the old generation anchors such as the venerably CQR and Bruce anchors.
I probably would not have written this if I was writing to you alone as you seem to be happy with your choices, as should every skipper. But I know there are others who are reading this stream of postings. Every skipper should make up his/her mind about gear on their boat, especially mission critical gear. I respond to postings with the head-set that I wish every skipper be as fully informed as reasonable and I share my experience, thoughts, and observations with that in mind.
I am also very interested in the safety aspects of our recreation and tend to write more fully when the question involves safety.
So, in that vein, I will comment that the fact that the re-setting issue has not happened to you in your anchoring experience, does not mean the anchor does not have this bad habit: I did say it was occasional: certainly many, possibly most, times the anchor resets well. But when it does not, safety for the boat and crew may be compromised.
Skippers should do their own research and data collecting. On a personal level I know of 3 OCC members who have had their Rocna classic with a roll bar not reset after a wind shift. I will also point to this bad habit being also fairly well documented on google and by Practical Sailor, and Attainable Adventures cruising has also had a number of its commentators speak to this. There are also a superb collection of videos of many anchor’s performance done by sv Panope which shows the habit in their series on the re-setting of the Rocna Classic.
Google and you will find all these sources quickly come up and more.
My best, Dick Stevenson, s/v Alchemy
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