h a l f b a k e r yThe mutter of invention.
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Flat Anchor
anchor that works by suction to ground and sea currents pushing it down | |
a large plastic mat holds to the sand not letting the chain pull
away tugging from the center. Looks like a large suction cup for
a
mobile phone holder in a car, /EDIT with the difference being
that it is flexible and free to fold over obstacles draping them
and covering them, but when pulled
forms a formiddable drag.
END OF EDIT/
It folds away, is much lighter than a
metal anchor, and anchoring the ship is much easier.
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Annotation:
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Marine environments are notoriously irregular; small rocks, vegetation, bits of rubbish, deceased mobsters ...any one of those would stop this from working. And a smooth, sandy bottom would offer no resistance to traction. |
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It would only work on a prepared (concreted) surface kept free of contamination. |
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//a smooth, sandy bottom would offer no resistance to
traction// There speaks the voice of experience. |
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How does it get down there? How does it stick? How does it unstick? How does it fold? |
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I was thinking this was a device to keep one's residence from
moving around. |
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Could make it soft like a tarp so it conforms to the terrain. |
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Unfortunately a regular anchor would work better. |
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I like the idea of an anchor that actively wriggles, like
a flounder (fish), to bury itself beneath the sand. |
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I think the whole thing depends on the forces acting on the
ship. A flat sheet that conforms to the sea bed, and is
tethered at its centre, will be very good at resisting sudden
upward forces. However, this is a Bad Thing, because if it
happens (for instance, because the ship is being lifted by a
large wave), you will soon have a shipful of water on the
bottom of the sea. If the lifting force is steady (for
instance, due to a rising tide), the sheet will simply lift up. |
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The sheet anchor will also be pretty useless at preventing
drift caused by wind or currents. It will just slide sideways. |
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It will also not be particularly easy to stow, because it will
have to be heavily reinforced to prevent the anchor line
from simply ripping out. |
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Also, metal anchors don't need to be particularly heavy.
They are designed to either dig in to a soft sea bed, or to
catch on rocks, not to act by weight alone. For a small (30-
50ft boat), the anchor need only weigh 10 or 20kg, if that.
For bigger boats, they are of course bigger but are still a
minuscule proportion of the boat's weight. |
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What is more important is the weight of the anchor chain,
which has to be heavy enough to form a decent catenary
that can absorb movement - otherwise you just rip the
chain out of your boat. An anchor chain is not meant to be
stretched taut between the anchor and the boat. |
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In short, as anchor designs go, this design is totally sheet. |
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//What is more important is the weight of the anchor chain,
which has to be heavy enough to form a decent catenary
that can absorb movement // |
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So what if you have a tapered chain? Make it heavy near the
center, but taper to the lightest possible weight to
withstand the tension near the anchor and near the boat.
It seem to me that would provide similar shock absorbing
qualities with less overall weight. |
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Possibly - I can't get my head around the catenary enough to
know. But then you'd need different chains for different
depths of water (and hence different anchor lengths). |
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