Half a croissant, on a plate, with a sign in front of it saying '50c'
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Flat Anchor

anchor that works by suction to ground and sea currents pushing it down
  [vote for,

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.

pashute, Jul 23 2019


       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.   

       It would only work on a prepared (concreted) surface kept free of contamination.
8th of 7, Jul 23 2019

       //a smooth, sandy bottom would offer no resistance to traction// There speaks the voice of experience.
MaxwellBuchanan, Jul 23 2019

       please see edit
pashute, Jul 24 2019

       How does it get down there? How does it stick? How does it unstick? How does it fold?
pocmloc, Jul 24 2019

       I was thinking this was a device to keep one's residence from moving around.
whatrock, Jul 29 2019

       Could make it soft like a tarp so it conforms to the terrain.   

       Unfortunately a regular anchor would work better.
doctorremulac3, Jul 29 2019

       I like the idea of an anchor that actively wriggles, like a flounder (fish), to bury itself beneath the sand.
sninctown, Jul 29 2019

       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.   

       The sheet anchor will also be pretty useless at preventing drift caused by wind or currents. It will just slide sideways.   

       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.   

       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.   

       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.   

       In short, as anchor designs go, this design is totally sheet.
MaxwellBuchanan, Jul 29 2019

       //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 //   

       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.
scad mientist, Jul 30 2019

       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).
MaxwellBuchanan, Jul 30 2019


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