Nomad Willy
Guru
This is a discussion on the merits of adjusting the weight of the rode's chain so as to ballast the rode to best advantage re the catenary and more importantly the angle of the rode on the bottom to horizontal. I'm going to copy and paste several posts that I made in an attempt to communicate this function.
Post #62
"Food for thought about the catenary because catenary is claimed to be the reason to use all chain.
Imagine a line attached to a tree about 10' up the tree. The other end is attached to a well set anchor about 50' away from the 1st tree. Lets assume about 3' of line droop (catenary) at about the middle of the rode. Place a heavy weight on the line about 3/4 of the way up the line from where it's attached to the anchor. What happens to the angle of pull at the attachment point on the ground at the anchor? Does the angle of pull on the anchor increase, decrease or remain the same?
Post #66
"Reality is that if you add weight to the upper end of the line (about 3/4 of the way up the rode) in my tree example and on a rode of a boat at anchor the rode near the anchor will rise providing it was not on the bottom or strung out straight. What does that tell you about the catenary effect of weight on the upper end of a rode? Simple logic will indicate that the added weight above will raise the rode a bit near the anchor having the opposite effect that chain huggers think happends. Or you can go fine two trees and get out some line and a weight ... and try it.
Post #78
"What I'm trying to communicate is that the bias of weight along a rode has a large effect on the capabilities of the rode re minimizing the angle of pull at the anchor.
I'll try it one more time. Go back to the tree. Tie a rope to two trees so there is considerable droop in the rope. Then put a heavy weight fairly close to one tree and mentally observe that now the rope will form a "V" shape if the weight is fairly heavy. The angle of the rope at each of the two trees will be different. Depending on the location of the weight the angle will vary. If the rope is horizontal the difference of the angle on each end will be maximum.
Here's another illustrative example. Lets say you're anchored and can attach a 200lb weight to the anchor 3' from the anchor. One hell of a Kellet one could say. A dramatic increase in holding power will result. Now take that 200lb weight and attach it to the rode 3' down from the bow roller. It will have practically no effect at all.
So now that one has a choice of where to put chain and line in the rode you can have a great effect on the rode's performance w no increase in cost. Of course there actually be a decrease in cost both in money and weight. This was not very practical before splicing to run through a gypsy was introduced. But it is here and seems dependable. So weight savings, cost savings and performance increases all at once are available w anchor chain weight bias along the rode. And if you are happy w the weight of an all chain rode just use 1/2 to 1/4 as long a chain of the same weight as the all chain rode for considerably more performance.
Lastly I should add a paragraph that Makobuilders wrote after my post #78.
"I believe that all your statements are accurate. That is why historically the boating references recommend at most one boat-length of chain or half the weight of the anchor. I also recall statements told from many commercial fishermen in Seattle about adding a fathom (or less) of extremely heavy chain as a leader, which seemed to solve alot of problems with dragging."
Post #62
"Food for thought about the catenary because catenary is claimed to be the reason to use all chain.
Imagine a line attached to a tree about 10' up the tree. The other end is attached to a well set anchor about 50' away from the 1st tree. Lets assume about 3' of line droop (catenary) at about the middle of the rode. Place a heavy weight on the line about 3/4 of the way up the line from where it's attached to the anchor. What happens to the angle of pull at the attachment point on the ground at the anchor? Does the angle of pull on the anchor increase, decrease or remain the same?
Post #66
"Reality is that if you add weight to the upper end of the line (about 3/4 of the way up the rode) in my tree example and on a rode of a boat at anchor the rode near the anchor will rise providing it was not on the bottom or strung out straight. What does that tell you about the catenary effect of weight on the upper end of a rode? Simple logic will indicate that the added weight above will raise the rode a bit near the anchor having the opposite effect that chain huggers think happends. Or you can go fine two trees and get out some line and a weight ... and try it.
Post #78
"What I'm trying to communicate is that the bias of weight along a rode has a large effect on the capabilities of the rode re minimizing the angle of pull at the anchor.
I'll try it one more time. Go back to the tree. Tie a rope to two trees so there is considerable droop in the rope. Then put a heavy weight fairly close to one tree and mentally observe that now the rope will form a "V" shape if the weight is fairly heavy. The angle of the rope at each of the two trees will be different. Depending on the location of the weight the angle will vary. If the rope is horizontal the difference of the angle on each end will be maximum.
Here's another illustrative example. Lets say you're anchored and can attach a 200lb weight to the anchor 3' from the anchor. One hell of a Kellet one could say. A dramatic increase in holding power will result. Now take that 200lb weight and attach it to the rode 3' down from the bow roller. It will have practically no effect at all.
So now that one has a choice of where to put chain and line in the rode you can have a great effect on the rode's performance w no increase in cost. Of course there actually be a decrease in cost both in money and weight. This was not very practical before splicing to run through a gypsy was introduced. But it is here and seems dependable. So weight savings, cost savings and performance increases all at once are available w anchor chain weight bias along the rode. And if you are happy w the weight of an all chain rode just use 1/2 to 1/4 as long a chain of the same weight as the all chain rode for considerably more performance.
Lastly I should add a paragraph that Makobuilders wrote after my post #78.
"I believe that all your statements are accurate. That is why historically the boating references recommend at most one boat-length of chain or half the weight of the anchor. I also recall statements told from many commercial fishermen in Seattle about adding a fathom (or less) of extremely heavy chain as a leader, which seemed to solve alot of problems with dragging."
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