Is There Such a Thing as 1:1 "Scope?"
- Thread starter Kings Gambit
- Start date
The OED is particularly useful for older English words, because part of the project was to gather examples of usage through the centuries. Many publications use it as the tie breaker, after Websters and others, in determining usage of old words, including nautical terms.
An interesting read and good movie on the topic is "The Professor and the Madman."
An interesting read and good movie on the topic is "The Professor and the Madman."
Scope is the length of line let out relative to the depth, so it is the hypotenuse (ignoring centenary). A 45º angle would be a 1.414 scope. An anchor rode hanging straight down is a 1:1 scope.
Both of your illustrations for talking about the steepness of a hill or roof measure SLOPE which is rise over run [vertical over horizontal]
I have never heard the expression "veered out." Is that common nautical vernacular, or your own invention?
It is common nautical vernacular - did it on all the large gray things I sailed on.
Allowing an anchor or its chain to run out using its own weight is called veering. With the windlass brake set, the ship is backed to set the anchor (cause the flukes to dig into the bottom). The brake is then released and the ship is backed down to veer more chain until it is at the desired scope. Stoppers are then set and the ship is anchored.
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Thanks. Maybe it’s enough to just say/write veered (rather than “veered out”).
A zero scope will not sink your boat. My anchor is always at a zero scope except when I am anchored. It is zero when stored on the bow roller.
Hmmm, that link takes me to the Oxford English Dictionary, but not to anything specifically nautical. I'll have to noodle around and see...
I have two hard copies of the OED in my library. I'll have to peruse those to see how they compare. I've never thought to use it looking for nautical terms ..
dj
A zero scope is what you have when the anchor is still on the bow roller. length of rode / depth 0:1
From the calculations and posts presented here, it appears that the lowest “functional scope” for anchoring might be about 1.4:1. This is where the rode, fully stretched out, could rise (toward the boat) at 45 d angle relative to seabed. I think this is a useful thing to know. Thus, the resultant vector shows that half of the force tugging on the anchor is directed along the seabed, and half is directed toward the surface, etc.
Thus, the resultant vector shows that half of the force tugging on the anchor is directed along the seabed, and half is directed toward the surface, etc.
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I think that the minimum scope for any anchor whould depend on the angle between the shank and the flukes. If the shank is pulled at an angle that does not allow the fluke to lay flat of the sea floor, it will have no hope of every setting. On my Mantus M1 that is about 2.5:1.From the calculations and posts presented here, it appears that the lowest “functional scope” for anchoring might be about 1.4:1. This is where the rode, fully stretched out, could rise (toward the boat) at 45 d angle relative to seabed. I think this is a useful thing to know.
That is an oversimplified model of how a rode or chain falls. It actually falls as a cateenary, and therefore is never straight, except, I suppose, when there's infinite force and infinite holding power. Which is all the better for us, as it means the part attached to the anchor is more horizontal than it would be otherwise.From the calculations and posts presented here, it appears that the lowest “functional scope” for anchoring might be about 1.4:1. This is where the rode, fully stretched out, could rise (toward the boat) at 45 d angle relative to seabed. I think this is a useful thing to know.
Maybe true, but most models of anything are oversimplified compared to “reality.” That’s why we use them to aid our understanding. Describe a system using as few parameters as is possible. That is, simplify it. Then go from there.
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Yes, I get that. Ours is even more complicated than just a chain catenary, too, in most cases, as we have chain spliced to rope. I would probably just count the rope as the scope if I had such a rode, but I have all chain.Maybe true, but most models of anything are oversimplified compared to “reality.” That’s why we use them to aid our understanding. Describe a system using as few parameters as is possible. That is, simplify it. Then go from there.
I've no idea from a theoretical perspective, but from a practical perspective I've always gone with 3:1 as a minimum scope. I would be mighty uncomfortable with anything less. I typically run more like 5:1 but in tight anchorages and not heavy conditions 3:1 seems good enough.From the calculations and posts presented here, it appears that the lowest “functional scope” for anchoring might be about 1.4:1. This is where the rode, fully stretched out, could rise (toward the boat) at 45 d angle relative to seabed. I think this is a useful thing to know.
dj
I'm sorry. I guess the firewall got it.
The nice thing about the on-line version (free through your public library) is that it contains ALL of the back up. A unabridged version of the OED is not a book, it is a volume that fills a room. Go to your library's page and look for it among the on-line resources. Or ask a librarian.