Nomad Willy
Guru
There is much talk about catenary and scope. Often, more often than it would seem necessary or appropriate.
But in many anchoring discussions I think it’s assumed that the anchor is in an ideal position somewhere north of 6-7 to 1 scope. And 10-1 talk sounds like “you can’t get better than that”. This post is saying you can.
Every anchor probably has an ideal angle of rode to fluke. At 10-1 scope w the rode at the anchor shank and laying flat on the seafloor one tends to think it’s an ideal arrangement. I think it may .... but it may not. Relative to a specific seafloor every anchor has an ideal angle to it’s fwd progress in the substrate relative to the angle of pull. The angle of pull is not the throat angle of the anchor.
If you discard the shank and put an eyebolt at various fore and aft positions along the fluke center the anchor fluke will assume a position based on a balance and when that balance positions the fluke at an ideal angle maximum resistance will give the anchor it’s maximum holding power.
But when all these positions, angles and balance come together it may not be at a 10-1 or even 7-1 scope. It may even happen at 5-1. No anchor test has ever addressed this issue or concept.
I read somewhere that one anchor in a test did better at a moderate scope than at a long scope ... like 10-1.
But I don’t see anchor tests turning into scope/holding power tests. First it would be too much work. But more importantly it would take down (IMO) the assumption that more scope is always better. I think that it’s possible 4-1 or 5-1 scope may be the best scope for performance.
Anyway I welcome any ideas that may shed light on the above. When I think about the ideal anchor I sometimes think of a joint in the shank that would allow the fluke to find it’s ideal angle. There are some big boat or ship anchors that articulate around a point in between the fluke tip and the crown. The Danforths articulate around and at the crown. There’s a lot to be gained by this (I think) and it’s related to ideal scope.
In this picture the articulation point is not at the crown like a Danforth. The articulation point is further fwd toward the fluke tip. This way there is not big pressure differences around the flukes but a more even fluke loading. With more even loading higher loading can be had overall.
But in many anchoring discussions I think it’s assumed that the anchor is in an ideal position somewhere north of 6-7 to 1 scope. And 10-1 talk sounds like “you can’t get better than that”. This post is saying you can.
Every anchor probably has an ideal angle of rode to fluke. At 10-1 scope w the rode at the anchor shank and laying flat on the seafloor one tends to think it’s an ideal arrangement. I think it may .... but it may not. Relative to a specific seafloor every anchor has an ideal angle to it’s fwd progress in the substrate relative to the angle of pull. The angle of pull is not the throat angle of the anchor.
If you discard the shank and put an eyebolt at various fore and aft positions along the fluke center the anchor fluke will assume a position based on a balance and when that balance positions the fluke at an ideal angle maximum resistance will give the anchor it’s maximum holding power.
But when all these positions, angles and balance come together it may not be at a 10-1 or even 7-1 scope. It may even happen at 5-1. No anchor test has ever addressed this issue or concept.
I read somewhere that one anchor in a test did better at a moderate scope than at a long scope ... like 10-1.
But I don’t see anchor tests turning into scope/holding power tests. First it would be too much work. But more importantly it would take down (IMO) the assumption that more scope is always better. I think that it’s possible 4-1 or 5-1 scope may be the best scope for performance.
Anyway I welcome any ideas that may shed light on the above. When I think about the ideal anchor I sometimes think of a joint in the shank that would allow the fluke to find it’s ideal angle. There are some big boat or ship anchors that articulate around a point in between the fluke tip and the crown. The Danforths articulate around and at the crown. There’s a lot to be gained by this (I think) and it’s related to ideal scope.
In this picture the articulation point is not at the crown like a Danforth. The articulation point is further fwd toward the fluke tip. This way there is not big pressure differences around the flukes but a more even fluke loading. With more even loading higher loading can be had overall.
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