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

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

+x

 

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

+x

 

Simon Currin - 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

+x

 

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

+x

 

Simon Currin - 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

+x

 

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

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.

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

P.S. my windlass design and capacity is also a major factor

+x

 

Sonia Johal - 28 Jan 2023

P.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

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

+x

 

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,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

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