Scope, All Chain Rode and Breaking Strength

[cr180]

Originally Posted by rslifkin

I agree that ground tackle weight shouldn't be overly limited on most cruising boats. The issue is that most boats carry all of the ground tackle weight right up at the bow where boats are the most sensitive to added weight, so it's easier to end up with a weight problem there than in many other places.

So have you thought about a dinghy on davits? Counteracts extra load in bow. We could have another lively debate on size and type of dinghy and OB hp.

[Breaking Waves]

Originally Posted by cr180

But if you undersized size ground tackle based on the notion that the ABYC tables have a safety factor of 3 to 5 on 42 knot wind data, then ???

There are two quite separate and distinct issues with respect to chain sizing/weight: breaking strength/loads and holding power/swinging

Empirically yachting chain (with at least minimal inspection/maintenance) really does not break in real-world anchoring usage. The failure is always somewhere else. This is empirically true even with boats with what we would all consider small chain.

However, boats do drag. And boats on rope do sail/swing in much wider areas than those on chain.

This to me means that the priority (my priority) is related to the holding/swinging factor, and the breaking strength/loads are secondary, almost a red herring. If you have the chain necessary to optimize the holding/swinging equation (which is complex) then you almost by definition also have sufficient chain strength (if it is at all decent chain).

How to optimize the system weight for best holding is a complex question and I don't know the answer. I personally believe there is a relatively broad sweet spot somewhere away from the extreme end solutions. If you examine the extreme ends of the options: all the weight in the anchor and a dyneema rode w/snubber you would be sailing all over the place in light and medium winds which would not make for a friendly fit into tight cruising anchorages and would also increase dynamic shock loads, and finally would essentially always place an up-angle load on the shank. I don't believe that is optimal. And the other end a huge chain and essentially no anchor - this would actually hold in some rocky/coral bottoms and have minimal swinging in light winds but would almost certainly drag in many conditions. So somewhere in between is probably real-world optimal but that leaves a huge range of options and I don't know how to optimize between them - I personally guess the curve is relatively flat there because a wide range of people are successful with a wide range of answers.

During my time cruising the paradigm shifted a bit - when we started you carried two different anchors (mid sized) on your bow and quite big chain (by current standards) . . . then it evolved and switched to one larger anchor on the bow and lighter chain. Honestly, both work if you have the skills and experience and knowledge suited to each. We went rtw once with each approach and had no anchoring trouble either way. Today, I personally think erroring toward the latter makes a bit more sense generally but it is a broad sweet spot of options and a good skipper can make anywhere in that spectrum work just fine

The ultimate answer to holding seems to be more seamanship skill-driven than gear driven to me. In the high latitude crowd, the group uses many different set-ups, pretty much none of us drag, and we almost never discuss ground tackle. It is just already solved skill problem for each of us.

[cr180]

Originally Posted by Breaking Waves

There are two quite separate and distinct issues with respect to chain sizing/weight: breaking strength/loads and holding power/swinging

Empirically yachting chain (with at least minimal inspection/maintenance) really does not break in real-world anchoring usage. The failure is always somewhere else. This is empirically true even with boats with what we would all consider small chain.

However, boats do drag. And boats on rope do sail/swing in much wider areas than those on chain.

This to me means that the priority (my priority) is related to the holding/swinging factor, and the breaking strength/loads are secondary, almost a red herring. If you have the chain necessary to optimize the holding/swinging equation (which is complex) then you almost by definition also have sufficient chain strength (if it is at all decent chain).

How to optimize the system weight for best holding is a complex question and I don't know the answer. I personally believe there is a relatively broad sweet spot somewhere away from the extreme end solutions. If you examine the extreme ends of the options: all the weight in the anchor and a dyneema rode w/snubber you would be sailing all over the place in light and medium winds which would not make for a friendly fit into tight cruising anchorages and would also increase dynamic shock loads, and finally would essentially always place an up-angle load on the shank. I don't believe that is optimal. And the other end a huge chain and essentially no anchor - this would actually hold in some roky/coral bottoms and have minimal swinging in light winds but would almost certainly drag in many conditions. So somewhere in between is probably real-world optimal but that leaves a huge range of options and I don't know how to optimize between them - I personally guess the curve is relatively flat there because a wide range of people are successful with a wide range of answers.

The ultimate answer to holding seems to be more seamanship skill-driven than gear driven to me. In the high latitude crowd, we have many different set-ups, pretty much none of us drag, and we almost never discuss ground tackle. It is just already solved skill problem for each of us.

But earlier on in this thread, you lobbied hard for test data showing a 3 to 5 safety factor in the ABYC data based on 42 knot winds. Then you said on your “rtw” cruise you used way heavy ground tackle than what I currently carry based on the 60 knot data provided by Mantus Anchors. Can’t have it both ways. More cruisers than me see through the hipocrosy.

[Breaking Waves]

Originally Posted by cr180

But earlier on in this thread, you lobbied hard for test data showing a 3 to 5 safety factor in the ABYC data based on 42 knot winds. Then you said on your “rtw” cruise you used way heavy ground tackle than what I currently carry based on the 60 knot data provided by Mantus Anchors. Can’t have it both ways. More cruisers than me see through the hipocrosy.

please read

I base my choices on holding power/swing and not loads.

Earlier I did not lobby for anything, I simply stated facts - that pretty much all measurements I have done or seen suggested significantly lower real world loads than abyc.

you are still obviously upset at me - you might be better to just put me on ignore until you calm down and can read and react more rationally

[cr180]

Originally Posted by Breaking Waves

please read

I base my choices on holding power/swing and not loads.

Earlier I did not lobby for anything, I simply stated facts - that pretty much all measurements I have done or seen suggested significantly lower real world loads than abyc.

you are still obviously upset at me - you might be better to just put me on ignore until you calm down and can read and react more rationally

No, you not only lobbied hard, but attempted to intimidate me for poor seamanship because I had a different opinion based on my Bahamas experience. Now I find out that you carry way heavier ground tackle than you would have ever selected based on your earlier arguments that the ABYC tables have “fat” safety margins. I’m passionate about this subject because I do not want new cruisers to be adversely influenced by you or others that exhibit such hypocrisy.

[Breaking Waves]

Originally Posted by cr180

intimidate me for poor seamanship because I had a different opinion based on my Bahamas experience.

really you need to chill out dude.

I can be a hard ass, calling it like it is, being as fact-based as I can . . . . but aligned with that I am about the least hypocritical person that exists.

And nothing I have said (in posts) above is inconsistent or hypocritical. It is a simple fact that all the data I have created and seen show the abyc numbers as high in the real world measurements, and that my own ground tackle really has very little to do with abyc and nothing to do with their load numbers and all to do with my experience in reducing swinging and maxmimizing holding across a wide range of conditions.

as to seamanship call - at least for me, it had little to do with the abyc argument and more to do with the situations you said you simply accept - potentially sitting on a lee shore with significant fetch in shallow water with little snubber in 60 kts. That is just an equation for one piece of bad luck or one mistake and losing your boat. Seamanship is designed to avoid situations like that.

[cr180]

Originally Posted by Breaking Waves

really you need to chill out dude.

I can be a hard ass, calling it like it is, being as fact-based as I can . . . . but aligned with that I am about the least hypocritical person that exists.

And nothing I have said (in posts) above is inconsistent or hypocritical. It is a simple fact that all the data I have created and seen show the abyc numbers as high in the real world measurements, and that my own ground tackle really has very little to do with abyc and nothing to do with their load numbers and all to do with my experience in reducing swinging and maxmimizing holding across a wide range of conditions.

as to seamanship call - at least for me, it had little to do with the abyc argument and more to do with the situations you said you simply accept - potentially sitting on a lee shore with significant fetch in shallow water with little snubber in 60 kts. That is just an equation for one piece of bad luck or one mistake and losing your boat. Seamanship is designed to avoid situations like that.

Not buying it and I hope others won’t either. So your argument that your own ground tackle has little to do with what you are strongly advocating new cruisers to select doesn’t wash. You are right about one thing. I am done with you. Your future posts won’t dignify my response.

[Breaking Waves]

Originally Posted by cr180

So your argument that your own ground tackle has little to do with what you are strongly advocating new cruisers to select doesn’t wash.

Two things:
(1) If I was making suggestions to a new cruiser I actually would NOT suggest most new cruisers follow my gear selection because most of them are not cruising in Patagonia/cape horn. I might suggest they read my wife's book because it is aimed at the broad coss section of cruisers.
and
(2) I looked back up thread just to double-check and that confirmed my posts focused on factually supporting/confirmed another poster's observation that real-world load measurements tended to be lower than the abyc load numbers.

I never made any (much less 'strongly advocated') suggestion or recommendations anywhere in this thread to any new cruiser about what safety factor might be appropriate for them or what size gear they should pick (hint - a safety factor is not a bad thing, but a regular and normal thing in an engineered product). In fact, the only comments I made about gear selection was to nolex (who is not a new cruiser) where I agreed that 'stout' was a good standard. And the one to you (and you have suggest you are also not a new cruiser) where I described what we used - and neither of those could be construed as suggesting weak gear.

Again, loads/breaking strength are separate and different from holding power/swinging room. Just as an example of how orthogonal they are - you can change the first by changing the chain grade without affecting the second.

I am done with you.

awesome, as I suggested above that's for the best for all of us.

.........

[captstu]

Constant force working load is not what causes the problem in my experience. I was anchored in a hurricane when the eye passed over and caused a significant veer. The boat ran down the chain out the other side and fetched up suddenly against the anchor.

I was anchored with Bruce with a fortress change the trip point. The Bruce tripped The fortress held and the 5/16 HT stretch significantly on my way, breaking the primary and back up nylon bridals in the process.

Be absolutely sure the ultimate braking strength is sufficient to stop your boat when it runs down in the veer.

[cr180]

Originally Posted by captstu

Constant force working load is not what causes the problem in my experience. I was anchored in a hurricane when the eye passed over and caused a significant veer. The boat ran down the chain out the other side and fetched up suddenly against the anchor.

I was anchored with Bruce with a fortress change the trip point. The Bruce tripped The fortress held and the 5/16 HT stretch significantly on my way, breaking the primary and back up nylon bridals in the process.

Be absolutely sure the ultimate braking strength is sufficient to stop your boat when it runs down in the veer.

Thanks for sharing your experience

[JordanH]

Originally Posted by rslifkin

Keep in mind, if you're going to add weight, adding it to the anchor will help more than the chain. I'd rather have 100 lbs of chain and 100 lbs of anchor than 150 lbs of chain and 50 lbs of anchor. The bigger anchor will give much more margin for short scope, poor bottoms, etc.

Uh-oh, you didn't read the assignment. The OP gave two options... the lighter chain (350' @ 231lbs) or the heavier chain (200' @ 231lbs). He is carrying the same weight of chain in both options with no mention of increasing the size of the anchor. So when we hold all else equal, we must assume the anchor, depth and scope etc. all remain the same.


(edit: that probably read too snippy. sorry, was just in jest. I think you also believe that the 200' chain option is better, after re-reading your previous posts.)


You've managed to change the premise of the question by having lighter chain of the same length and increasing anchor size.

All else equal, the heavier chain is the better chain.

[Pelagic]

Originally Posted by captstu

Constant force working load is not what causes the problem in my experience. I was anchored in a hurricane when the eye passed over and caused a significant veer. The boat ran down the chain out the other side and fetched up suddenly against the anchor.



I was anchored with Bruce with a fortress change the trip point. The Bruce tripped The fortress held and the 5/16 HT stretch significantly on my way, breaking the primary and back up nylon bridals in the process.



Be absolutely sure the ultimate braking strength is sufficient to stop your boat when it runs down in the veer.

That's a great example of "Breakaway Sheer" with your experience being the worst, when the eye passes directly overhead.

You are actually advised in some commercial Seamanship texts that during the eye, you reset and reposition your ground tackle for the anticipated new direction.

Stories of Tug and Barges at anchor making that adjustment

[Breaking Waves]

Originally Posted by JordanH

All else equal, the heavier chain is the better chain.

except (generally) for sailing performance. . . which also is important to many of us.

There are compromises to almost everything.

[JordanH]

Originally Posted by Breaking Waves

except (generally) for sailing performance. . . which also is important to many of us.

There are compromises to almost everything.

231 lbs of light chain or 231 lbs of heavy chain. It will affect your sailing performance the same. ;-)

Again, the OP gave 2 options, both the same weight, but different lengths.

[rslifkin]

Originally Posted by JordanH

Uh-oh, you didn't read the assignment. The OP gave two options... the lighter chain (350' @ 231lbs) or the heavier chain (200' @ 231lbs). He is carrying the same weight of chain in both options with no mention of increasing the size of the anchor. So when we hold all else equal, we must assume the anchor, depth and scope etc. all remain the same.


(edit: that probably read too snippy. sorry, was just in jest. I think you also believe that the 200' chain option is better, after re-reading your previous posts.)


You've managed to change the premise of the question by having lighter chain of the same length and increasing anchor size.

All else equal, the heavier chain is the better chain.

In reality, that probably depends on where you cruise. If you don't want to transfer some of that weight into the anchor or anything else, then in most places, the heavier chain is probably better. But if in places where bottom chafe is a concern along with deep water anchoring, then I'd want the longer chain.