We are working on single family seastead designs.  They usually have 3 or 4 legs/floats/columns that go down into the water with the living area
well above the water.  So they are a bit like tiny oil platforms.

It would be interesting if when they came to a new country instead of just dropping an anchor they could
put a mooring screw into the sand below each leg and pull down a bit to turn the seastead into
a "tension leg structure".  

It is not clear yet if customers will move around frequently like yacht families or if they may move less often.
So it would be nice if it was not too much work to put in the mooring screws.

Pulling down just takes a winch.  So the tricky part is putting the screws in and out.

Our single family seasteads seem to usually be in the range of 20,000 lbs to 60,000 lbs.
Our designs go down into the water between 6 feet and 15 feet.

I imagine it might be possible to often find a spot where the sand was just a few feet below
the bottom of the seastead but it could be nice to have the flexibility to operate even
if the bottom was 100 feet below if that is not too much more costly.

Our first market for the Seasteads will be the Caribbean, which has very small tidal swings,
usually less than 1 foot.  The seastead legs have a small waterline area, so 1,000 or 2000 lbs
can pull the seastead down 1 foot at that leg.  I think that 5000 lbs pull on each leg
would make the seastead very stable for normal weather.  Not sure what storms and waves might
do, or if we should even try to design for that.

For pulling up on the mooring screw, a regular boat anchor windlass could handle 5000 to 10000 lbs?
If we have one by each leg this might be enough to pull down the seastead?

To start for shallow water we could do the following.  Have a detachable lever (maybe 10 feet)
that can connect to the top of a mooring helical screw.  A person goes in the water and gets 
the screw started by turning the lever by hand.   Then a rope is attached from the end of the
lever to the dinghy and the dinghy is driven in circles around and around to pull the lever and
make the screw go in.  Then the person detaches the lever and attaches the rope to the winch is attached.
Then this is repeated for each.   It is a fair amount of work but it is cheap and will get the job done.
But some point it would be reasonable to pay for something more automated, worked in deaper
water, and was less work.

I am thinking of a possible design to make installation and removal very easy.  Imagine the shaft
on our screws are not round but square shape.  The shaft can be
like 8 feet long with cable attached at the top and screw part on the lower foot or so, maybe
1 foot diameter screw.  A device that slid down the cable and over the
shaft down to near screw part (it will have rollers that contact the shaft).  The device will have tripod legs that 
are around 10 feet and angled so they support the device just above the actual screw part of the helical screw.
For storage the tripod legs will at least fold and
might even telescope like a camera tripod.  It will have a big gear, the center of which is
against the square shaft (with rollers).  So a geared down motor can turn the shaft and drive in or out the screw.
The legs can be long enough and have a food shape that resists moving over the sand (maybe a little plow).
As the screw goes in the shaft will move down and the point of contact between the device and
shaft changes but the whole shaft will be the shape that lets the device get a good grip. 
So this could be lowered down the cable going to the screw and it would naturally get in the right 
position.  The cable to the screw can be lifted up and lowered again if the tripod is not level on
the first lowering.  Depending on water depth this may require some underwater camera to see that
it is set ok.  The device can be powered from a cord easily as the device does not spin.  The rope to the screw
needs a shackel as it will spin.  To move to the next screw the drive would be brought to the surface
and the rope from the first pulled out and then the device put over the rope for the next screw.
What do you think of this type of design?

Are there any existing robots/ROVs/tools for easily putting in and taking out mooring screws?
It would be easier to just buy something than to have to design a custom solution.

Can you think of another design for putting in the screws and taking them out that you like better?
How would it work?   How long would it take?  How much human effort/time would it take?
How much would it weigh and how much would it cost if made in China (say batch of 20)?
Maybe make a price range for different sizes if that makes a difference.