The floatability of platforms can be increased to twice the buoyancy of air volume if the structure is placed with the bottom open to the ocean, as of diving bell. As the structure is inserted in the ocean the air inside is trapped and compressed which exerts an upward force. If an external air compressor is used to pressurize the air within the structure then , the air pushes the water content to the edge of the open structure. Thus increases the pressure and increases the buoyancy as well as the upward force exerted by the air.By this way we can increase the load carrying capacity by twice,
The keyword to google it is “caission”…
But the caisson doesn’t float , they are rested on the solid bed of water bodies.https://drive.google.com/file/d/1wN1FLqRTPbPYKi21kuZmfgwNoXH7q3kR/view?usp=drivesdk
Yeah , it may not increase the buoyancy force but it can reduce the vibrations due to surface waves in ocean.
I had research such “reverse buoyancy” floating structures years ago. My major concern was that in high seas, due to the wave action, air will end up underneath the “hull” and create a gradual loss of buoyancy.
As long as air can be pumped in to compensate, everything will be OK. But if not, in case of a major electric failure to the air pumps, that baby will go down like a rock.
Way too risky when people lives are at stake. IMHO
If the open surface is left at the surface of water , then it is vulnerable to such circumstances, but the surface is deep inside the water hence the waves cannot affect it. If we are affected by the rough Climate then instead of pumping in air , we can suck air to create the vacuum pressure which can hold the platform tight to the surface https://drive.google.com/file/d/11iCkxM_NNbwdQ8taWGIzlnRBOClZF_q0/view?usp=drivesdk
I’m pretty sure noboxes has already commented on this if you can read between the lines…but compressed air is less buoyant than normal air - it weighs more.
… that, and your inverted cup gets top-heavy and unstable, when you don’t have it ballasted…
Catamarans are unballasted, and are top heavy too. You can side-step some reality without breaking all the physics.
The description was of a diving bell… Presumably said diving bell is ballasted, but pushing the C.O.G. of the bell upward, by keeping it filled with air is going to destabilize it…
Agreed. I think commercial bells have a platform below the bell, which holds spare tanks and diver weights and other goodies, unintentionally providing a lower ballast. For an unsealed, always-open bell, it could be made of plastic, as the air pressure is equal to the water pressure.
Top heavy? Catamarans and multihulls in general can have some of the lowest metacentric heights of any powered vessels. You might need more than a 90 IQ to figure how to do this because most plans from naval architects refuse to put seaworthiness over docking ability/accommodation, but it can be done.
Sure, but if it’s above the waterline, it’s top heavy.
That’s an uneducated remark,… Why comment if you have no clue,…
Ok, i should have thrown in all the buzzword caveats, like “apparent”, and “calculated” and “for a given heel angle”, and “for values of acceleration” and “for a given hull shape” and “loading at that time”. I was trying to be really simple. I lose again.
I meant when it comes to a cat…
But I wouldn’t choose a cat hull for a seastead’s hull design. A “simple mono hull” would do excellent. By me.
Also, it doesn’t really matter if you are top heavy or not “early” in the project,…if you gonna end up here.