Brute-force approach
This is the procedure for getting the platform from the hole in the ground in which it was cast, into the water. It is described for the ¼ scale experiment, because it will not be practical with the 300 ton full scale module. This may still be problematical, the item weighs 3.3 tons. It will require 3-4 people.
Dig out a track from the platform
into the pond.
Anchor a steel cable to several trees
across the pond.
Couple it via cable and pulley to
form a sling around the platform through the tiedowns.
Drag it into the water with a
come-along.
Hazards: If the cable snaps, heads, or other body parts, could roll. Have care not to get pinned beneath the platform, ie stay to the sides, keep away from front and rear.
Alternative airbag scheme
This is a speculative way to launch the 50 foot module, that will be easy, if it works. It must be tried out on the ¼ scale module first. If it fails, we fall back to the brute-force method above. The idea is to construct a large air bag from the 6 mil poly, like we do for the water bags. We place it under the poly layer that lines the bottom of the mold. When ready, we inflate the bag to raise the platform up a few inches. It's counter-intuitive, but the pressure in the bag is .53 psi under the ¼ scale, and only 1.07 psi under the full scale module. This corresponds to tension forces of 1.06 and 2.14 lbs , respectively across a linear inch, no threat to 6 mil poly. The hazard is punchuring the bag with something sharp left in the pit, or whatever.
Now wait a minute! Thats not the way I figured tension in a wirerope ring around the perimeter wall. Need to review the physics. Anyway:
Smooth out the bottom of the pit and
clear the walls of sharps.
Lay out a 6 mil poly airbag same flat
diameter as the platform.
Route inlet hose under
wall on uphill side.
Cover bag with the layer
of poly that will retain the concrete.
Cast and cure the
platform.
Dig out a path from
platform to water and clear of sharps.
Inflate the airbag with
a compressor until the platform is lifted 6 inches.
Place another airbag,
same diameter, 1 foot downhill of it.
Inflat the second bag to
5 inches above ground.
Give the platform a
push.
It should zoom downhill
after it reaches the lip with almost no friction.
For a long path, more
bags may be needed.
If this gets out of control, the momentum will be awesom. If this doesn't work on the ¼ scale model, we will have to look at the track mechanism (the 'ways') used to launch large vessels in a shipyard.