So we spoke about scuppering cargo vessels until nightfall. I advised a common vessel larger than required. First distribute weight to make it bottom heavy. Lead a tube from another vessel pumping air.
How heavy can it be before refusing to float upward? Red line on Hull.
How light before keeling over? Mark the Hull
Can water be used in cells if carrying polystyrene?
How large do the air tanks need to be?
When you've done that start converting a real one & practice hover with the first. Proper weight distribution can be checked looking over the side at marks on the hull, water pump adjust.
Oil tankers are bottom heavy requiring ballast cells pumped with water to prevent listing & a cellular hold, prevents oil slicks. Can tow a short range sub.
