Anchor attachment point to rode
- Thread starter fred1diver
- Start date
simple math. 4 to 1 ratio whether it is chain or line is 4 to 1. same with 7 to 1.
just like the 3rd grade math teaser. what weighs more a lbs of feathers or a lbs lead.
vectors baby.
this will be taught to you by trained instructors if getting your masters up here on the lakes. on sailboats of the size we all sail here the only reason for using chain is chaffing.
now, if you claim that you use a 3 to 1 scope because the the sag in the chain will help it set. well, might get away with that on a calm night. BUT, you still are not 4 to 1 are you. bad choice, that's not how i roll.
personal experience: 60 yrs sailing the lakes, ships and boats, never heard of one case of a rope rode being an issue. let's face it, chain is a major pain. dirty, nasty, heavy bulky, ugly, expensive, that many store above the water line which is the worst place for all that weight. above the water line all the way forward in the bow. really, that's not how you load a vessel.
just like the 3rd grade math teaser. what weighs more a lbs of feathers or a lbs lead.
vectors baby.
this will be taught to you by trained instructors if getting your masters up here on the lakes. on sailboats of the size we all sail here the only reason for using chain is chaffing.
now, if you claim that you use a 3 to 1 scope because the the sag in the chain will help it set. well, might get away with that on a calm night. BUT, you still are not 4 to 1 are you. bad choice, that's not how i roll.
personal experience: 60 yrs sailing the lakes, ships and boats, never heard of one case of a rope rode being an issue. let's face it, chain is a major pain. dirty, nasty, heavy bulky, ugly, expensive, that many store above the water line which is the worst place for all that weight. above the water line all the way forward in the bow. really, that's not how you load a vessel.
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Interesting as I have read a lot of stuff about the “value” of using chain as part of the rode. I certainly am not disputing your position as it’s based on a lot of experience and a career on the water.
Personally I rarely anchor other than in sheltered bays to go for a swim so the idea of getting rid of the chain has its appeal for all the reasons you state. Hmmmmm
if there is coral, chain is a must. i would love you to show me an article that says chain is needed or gives you an improved position up on the great lakes. then even worse, some boats put windlasses and ground tackle way high and forward. not good at all. on the ships the chain goes all the way down to the bottom of the hull.
In the absence of coral or rock, I think it is true that you don't need chain, with emphasis on the word need.
Probably most boats under 32 feet in soft bottom, brown water areas, use mostly rope, and we don't hear a lot about chafe. The risk we hear most about is wrapping the rode around the keel (either tide or current can do that), and that is solvable with smart use of a kellet.
The bigger the boat the greater the risk of chafe. Small boats have limited rode pressure against rocks, larger boats have much greater cutting force. In my case, I use over-sized 1/2-inch nylon, because I had it and because it is easier to grip than the 3/8-inch the boat actually needs. And it also reduces my cutting risk disproportionatly, because there is more to cut and because the spot-pressure on a rock is lower. I also like the reduced stretch (no bungee).
Some anchors like chain for the initial bite when setting. Not pivoting fluke anchors, which often do better with no chain in soft mud. But it doesn't take much. 10 feet is enough for that. I've used all manner of old-style and new generation anchors with little or no chain. My fortress kedge on my cruising cat had no chain (easier to row out). It did have a covered Dyneema chafe leader.
Boats with rope swing more. This depends on the boat; a multihull on a bridle doesn't swing because of the wide bridle. You can use a riding sail, kellet, or hammerlock as well.
With chain you can anchor in less space... until it really starts to blow (>60 knots). Then I'm not so sure it matters.
And finally there is catenary. It helps, but so does nylon and more scope. With rope you will have to use slightly more scope. For example, when 3:1 might work with chain, you will need 5:1 with rope. When it blows rope rode users got to long scope sooner, but once we get out to 12:1, there is no difference.
Is chain good? Yes, it solves a lot of problems. The anchor sits a little more quietly. The windlass likes chain. Do you always need it? No. Is it easier to live with on may boats? Yes. Either can work, if you know the rules. Horses for courses.
[I've cruised with all-chain and with only 6 feet of chain.
Probably most boats under 32 feet in soft bottom, brown water areas, use mostly rope, and we don't hear a lot about chafe. The risk we hear most about is wrapping the rode around the keel (either tide or current can do that), and that is solvable with smart use of a kellet.
The bigger the boat the greater the risk of chafe. Small boats have limited rode pressure against rocks, larger boats have much greater cutting force. In my case, I use over-sized 1/2-inch nylon, because I had it and because it is easier to grip than the 3/8-inch the boat actually needs. And it also reduces my cutting risk disproportionatly, because there is more to cut and because the spot-pressure on a rock is lower. I also like the reduced stretch (no bungee).
Some anchors like chain for the initial bite when setting. Not pivoting fluke anchors, which often do better with no chain in soft mud. But it doesn't take much. 10 feet is enough for that. I've used all manner of old-style and new generation anchors with little or no chain. My fortress kedge on my cruising cat had no chain (easier to row out). It did have a covered Dyneema chafe leader.
Boats with rope swing more. This depends on the boat; a multihull on a bridle doesn't swing because of the wide bridle. You can use a riding sail, kellet, or hammerlock as well.
With chain you can anchor in less space... until it really starts to blow (>60 knots). Then I'm not so sure it matters.
And finally there is catenary. It helps, but so does nylon and more scope. With rope you will have to use slightly more scope. For example, when 3:1 might work with chain, you will need 5:1 with rope. When it blows rope rode users got to long scope sooner, but once we get out to 12:1, there is no difference.
Is chain good? Yes, it solves a lot of problems. The anchor sits a little more quietly. The windlass likes chain. Do you always need it? No. Is it easier to live with on may boats? Yes. Either can work, if you know the rules. Horses for courses.
[I've cruised with all-chain and with only 6 feet of chain.
thin, of course to much of what you wrote. like the 'need' part. now what about that rope has stretch and chain does not. my rope gets fed the the sailing winches if needed. where did you come up with this 12 to 1 ratio. with all my experience and all courses i took and training by many, i've never heard of that one. who dreamt that one up.
^^ The math of anchoring is a continuum. If you go by any over simplified group of rules, you will be wrong some of the time. I didn't state any specific conditions or bottom type where one might use 12:1. I said that when we do, there will be no difference (in holding capacity) between rope and chain. However, if you are using in-line tandems and learn the math, you will learn that 12:1 is probably the minimum safe scope (Peter Smith) and 20:1 is not unreasonable on some bottoms. Google it. I've tested it.
I think the people who cruise and live aboard dreamt that one up. I was once anchored in 12' of water with 90' of chain and 10' of nylon rode deployed. The wind picked up as forecasted, and when it hit 55 knots, most of the chain was out of the water. The anchor held.
My mistake. That was 100' of chain and 10' of nylon rode.
20' of water depth, another 5' up to the chock, with your supposed 12 to 1 and or 20 to 1 would indicate 500' of chain and or rope. Thin, it don't add up. peter smith, ok, manufacturer , salesman, yachtsman, ........
nov 10th, 1975, it was blowing 105 mph going thru the breakwall at lackawanna. i was the bosun on the fordeck. we dropped the 2 seven ton anchors on the bow with about three shots of chain each. the second mate was on the stern with a seven ton anchor that he dropped as well. when the stern cleared the opening the old man rang up full speed astern with that chain out the back. we had 1500' ish to the far side of the harbor. we fought hard, earned some luck and won.
Take a look at this article. It is consistent with what you are saying. When conditions start to get interesting, the chain is going to flatten out anyway. Scope is key. Now, abrasion resistance is a different matter altogether.
Yes it does. I've done this. First, 20 feet is your assumption. Let's say 6 feet depth, for a total of 9 feet. That makes 108 feet, no problem there. Next, set two anchors in tandem. Dive on the anchors and watch the nearer anchor lift as soon as the wind hits 15 knots. Right off the bottom. Look the Peter Smith drawing, which anyone will tell you is mathematically correct. Then ease the scope to 20:1 (180 feet) and both anchors stay on the bottom.
I'm not saying this is common. It is very, very rare. It is something you only do on slate, cobbles, or hardpan, so no, it does not apply to you. I'm saying you need to understand ALL of the math before you set simple rules. I disagree with Peter on many things, but in this case both the math and practice say he is right. The US Navy has also researched this.
I have no interest in scope vs. hold arguments. I have tested anchors and a range of scopes and published the data. I've done the same with catenary. You have to consider wind, bottom, anchor type, chain weight, yawing tendancy, and depth before you can talk about scope. Or you can just pick a "rule" that fits your boat and the places you go.