China’s very large floating platforms are in the design and research phase for floating airports. Floating airports have been built in the past using pontoon structures and there are many interesting floating airport and floating city designs. The modular designs seem the most interesting.
Jidong Development, a state-owned company, is contributing most of the research funding to the joint project, local media reported. This first VLFS, being built near Beijing, would be used as a “deep sea comprehensive security base.”
US Navy built a 550 meter long airstrip on pontoons in WW2
Japan built test airstrips when investigating the idea for Kansai International Airport
Pontoon-type VLFSs are also known in the literature as mat-like VLFSs because of their small draft in relation to the length dimensions. Very large pontoon-type floating structure is often called Mega-Floats. As a rule, the Mega-Float is a floating structure having at least one length dimension greater than 60 meters. Horizontally large floating structures can be from 500 to 5000 meters in length and 100 to 1000 meters in width, while their thickness can be of the order of about 2-10 meters.
Aircushion supported Mega-Floaters are mega floaters that are supported by an air cushion
PhD student Jan van Kessel calculated a way to make mega-floaters more resilient. Breakwaters have always sheltered large floating structures from the waves. In his thesis, entitled ‘Aircushion supported Mega-Floaters’, he presents and calculates another form of floating entirely. Not an immense barge, but rather a bottomless box, floating on a ‘cushion’ of encapsulated air. Think of a shoebox without its lid, turned upside down and placed in the water. Van Kessel shows that the forces on a floating shoebox structure are about half of those on a conventional closed barge. Besides, he argues, the use of aircushions to make things float offshore isn’t new. Forty years ago, gigantic oil storage tanks in Dubai were constructed on land, lifted by pressurised air and towed to their offshore locations, eventually sinking on the spot.
The most logical mega-floating structure needed in the near future is an offshore airstrip. A 3800 meter long runway could land any current plane. The most plausible place for this airstrip would be off the coast of Singapore, since it is a densely populated city-state that has little else to extend to other than the seas.
The mobile offshore base (MOB) idea was first seriously considered when the United States entered Operation Desert Shield (1990–91). MOB is a concept for supporting military operations where conventional land bases are not available. With the MOB concept the U.S. could have a base anywhere in the world in as little as a month. A MOB could accomodate and deploy conventional fighters and even large carge aircraft like the C-17 Globemaster III as well as landing craft.
The largest floating structure was a kilometrer-long floating airstrip in Tokyo Bay. At 149 million dollars, it was a costly experiment to see how well a floating airstrip would perform. Experiments performed after its completion in 1999 showed that there were no significant differences between a land-based runway and a floating one. Quod erat demonstrandum. Afterwards, this structure was dismantled.
Freedom Ship a MegaFloat luxury cruiseship proposal
Floating Cities proposed
Economic Viability of large floating structures for seasteading
William Reidy gives a talk about the Economic Viability of Large Floating Structures at the Seasteading Conference 2012. Willian Reidy is Executive Director at The Maritime Alliance.
Lawrence Livermore Labs had an offshore port design for national security objectives
Another big floating city concept