# Maximum size limits for floating structures (water and air)? **URL:** \ **Category:** Factual Questions\ **Created:** [May 22, 2007, 2:40am UTC](https://boards.straightdope.com/t/maximum-size-limits-for-floating-structures-water-and-air/405016 "2007-05-22T02:40:42Z")\ **Posts on this page:** 15\ **Page:** 2
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [May 25, 2007, 1:33pm UTC](https://boards.straightdope.com/t/maximum-size-limits-for-floating-structures-water-and-air/405016/21 "2007-05-25T13:33:38Z")
It might be possible to build it in modular form; each bit having its own directional propulsion system (on the underside, to minimise thrust against adjacent modules) that could be networked to act in unison. Link the modules together with a hydraulic rams that drive pumps when the modules move relative to one another - the modules around the perimeter of the collection would not only damp out most of the swell (leaving the central ones quite stable), but would generate power as they did it. I’m sure there would be a thousand technical problems to overcome, but I can’t think of anything immediately insurmountable doing it this way. If you were cunning enough with the linkage system (I’m thinking of Rubik’s cube here - where you can move the parts relative to one another without ever detaching them), you could even reconfigure the module arrangement and ‘squirt’ the island through a large canal or strait or something. ---
**Author:** ![Mr.Slant](https://avatars.discourse-cdn.com/v4/letter/m/c57346/32.png) [@Mr.Slant](https://boards.straightdope.com/u/Mr.Slant)\ **Post date:** [May 25, 2007, 1:48pm UTC](https://boards.straightdope.com/t/maximum-size-limits-for-floating-structures-water-and-air/405016/22 "2007-05-25T13:48:03Z")
Oooh. If I had one, I could finally order my crew to “separate saucer section.” I like it. ---
**Author:** ![KP](https://avatars.discourse-cdn.com/v4/letter/k/a9adbd/32.png) [@KP](https://boards.straightdope.com/u/KP)\ **Post date:** [May 25, 2007, 2:10pm UTC](https://boards.straightdope.com/t/maximum-size-limits-for-floating-structures-water-and-air/405016/23 "2007-05-25T14:10:11Z")
On the man-made, self-sustaining iceberg front, The WWII Project Habakuk seems your best bet. It’s built of Pykrete (ice with wood pulp frozen in) I don’t recall the optimum ratio (16% pulp?) but you can easily Google Pykrete. IIRC, Wikipedia had a nice entry. Pykrete is somewhat self-insulating, and has remarkable resistance to melting, as well as being remarkably tough (Lord Mountbatten demonstrated this by firing a gun at a block of ice and shattering it; the bullet he shot at the equivalent Pykrete lock bounced back to hit US Adm Ernest king in the leg (or penetrate his pants leg, depending on the account). A “Habakkuk” ship was built, using cardboard tubes for cooling air. When the project was abandoned, the ship didn’t melt until well into the summer. With a roof of solar cells providing both shade and some fraction of your refrigerating power, your energy needs might not be _as_ atrocious as one might imagine ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [May 25, 2007, 7:37pm UTC](https://boards.straightdope.com/t/maximum-size-limits-for-floating-structures-water-and-air/405016/24 "2007-05-25T19:37:56Z")
[QUOTE=Mr. Slant] Oooh. If I had one, I could finally order my crew to “separate saucer section.” I like it. [/QUOTE] I wrote a _Star Trek_ short story a few years ago in which an _Intrepid_-class starship, like _Voyager_, puts down in an ocean on a Class-M world. She floats without any problem. The chief engineer adjusts the gravity field to prevent seasickness in the crew, and they leave a satellite overhead to keep an eye on local weather and to warn them of any freak waves. Otherwise, no problem. They even open some of the upper airlocks and go swimming off the upper primary hull. 😃 ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [May 25, 2007, 8:35pm UTC](https://boards.straightdope.com/t/maximum-size-limits-for-floating-structures-water-and-air/405016/25 "2007-05-25T20:35:22Z")
\>Earth is not floating in the atmosphere. It is not being held up by the force exerted by the surrounding fluid (atmosphere). Well, it is floating, and it’s surrounded by atmosphere, but its buoyancy in air is unimportant in keeping the system the way it is. So we are interested not just in floating but in the buoyant kind of floating. More to the point, perhaps a better reference is the Sargasso Sea, which is a floating agglomeration of seaweed and the like out in the Atlantic Ocean. I’ve heard it sometimes amounts to a big island. It stays there because surface currents flow together and meet at that location, only to descend together, and because it’s composed of lighter materials that don’t descend with the currents. Somebody has proposed farming it. ---
**Author:** ![Sapo](https://avatars.discourse-cdn.com/v4/letter/s/ec9cab/32.png) [@Sapo](https://boards.straightdope.com/u/Sapo)\ **Post date:** [May 25, 2007, 8:56pm UTC](https://boards.straightdope.com/t/maximum-size-limits-for-floating-structures-water-and-air/405016/26 "2007-05-25T20:56:04Z")
[QUOTE=Napier] \>Earth is not floating in the atmosphere. It is not being held up by the force exerted by the surrounding fluid (atmosphere). Well, it is floating, and it’s surrounded by atmosphere, but its buoyancy in air is unimportant in keeping the system the way it is. So we are interested not just in floating but in the buoyant kind of floating. [/QUOTE] :dubious: please, define floating. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [May 25, 2007, 10:35pm UTC](https://boards.straightdope.com/t/maximum-size-limits-for-floating-structures-water-and-air/405016/27 "2007-05-25T22:35:59Z")
[QUOTE=Napier] Now, which column are we talking about? It must be centered on Maryland, because the sky is right above me. What do the Australians see when they look overhead? Are they jammed right up against the bottom of the column? [/QUOTE] No silly, they’re jammed up against the turtle shell. ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [May 25, 2007, 11:39pm UTC](https://boards.straightdope.com/t/maximum-size-limits-for-floating-structures-water-and-air/405016/28 "2007-05-25T23:39:22Z")
Heck, the continents are floating. Or at least drifting. ---
**Author:** ![Sam\_Stone](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Sam\_Stone](https://boards.straightdope.com/u/Sam_Stone)\ **Post date:** [May 26, 2007, 12:50am UTC](https://boards.straightdope.com/t/maximum-size-limits-for-floating-structures-water-and-air/405016/29 "2007-05-26T00:50:23Z")
One of the problems with very large floating structures is that they cannot follow the peaks and troughs of waves. A smaller boat will ride up and down with a wave, but a bigger ship may find itself with the bow at the peak of one wave, and the stern at the peak of another, with nothing supporting the middle. Then the back of the ship breaks, and it sinks. So you either have to build something small enough to ride each wave, or something strong enough to hold its own weight when supported at each end only, or something so massive that the size of the wave troughs is insignifiant, or you have to make your floating thing flexible so that its various parts can ride the waves. The last would kind of suck from a livability standpoint, so we’re left with really really big, average sized, or really really strong. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [May 26, 2007, 1:01am UTC](https://boards.straightdope.com/t/maximum-size-limits-for-floating-structures-water-and-air/405016/30 "2007-05-26T01:01:03Z")
My hypothetical modular design should be able to work around that - the middle should be more or less damped to level - the edges would wave. ---
**Author:** ![Sam\_Stone](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Sam\_Stone](https://boards.straightdope.com/u/Sam_Stone)\ **Post date:** [May 26, 2007, 1:10am UTC](https://boards.straightdope.com/t/maximum-size-limits-for-floating-structures-water-and-air/405016/31 "2007-05-26T01:10:08Z")
As for the size of things that float in air, how about a [balloon that can fly into orbit](http://www.msnbc.msn.com/id/5025388/)? Such a balloon couldn’t stand the jostling of the lower atmosphere, so it would be assembled at a permanently floating ‘airbase’, and fly between that base and orbit, well above the weather. The balloon (called the ‘ascender’), would be 1.8 kilometers long. That’s pretty big… ---
**Author:** ![commasense](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/commasense/32/3017_2.png) [@commasense](https://boards.straightdope.com/u/commasense)\ **Post date:** [May 26, 2007, 3:53am UTC](https://boards.straightdope.com/t/maximum-size-limits-for-floating-structures-water-and-air/405016/32 "2007-05-26T03:53:56Z")
Read up on Buckminster Fuller. > [@](#): > > Buckminster Fuller proposed that as spheres of great size are considered, the amount of air enclosed grows huge compared to the weight of the sphere. Of a sphere with a radius of 1320 feet, the weight of the enclosed air is 1000 times greater than the weight of the sphere’s structure. If that volume of air was heated only one degree, the sphere would begin to float! > > Geodesic spheres larger than half-a-mile in diameter can be floated in the air, like clouds. Draped with polyethylene curtains – to retard night-time air intake – the spheres would be light enough to remain aloft, at preferred altitudes. > > “Cloud nines” one mile in diameter could house thousands of people, whose weight would be negligible. Passengers could pass from “cloud” to "cloud,‘’ or from “cloud” to ground, as the “clouds” float around the Earth or are anchored to mountain tops. The "clouds’’ could become food factories by impounding sunlight. [From here.](http://www.cjfearnley.com/fuller-faq-5.html) Fuller also had ideas for floating structures on water: > [@](#): > > Triton was a concept for an anchored floating city that would be located just offshore and connected with bridges and such to the mainland. It was a collection of tetrahedronal structures with apartments and such. > > Floating cities are designed with the most buoyantly stable conformation of deep-sea bell-buoys. Their omni-surface-terraced, slope-faced, tetrahedronal structuring is employed to avoid the lethal threat of precipitous falls by humans from vertically sheer high-rising buildings. > > Fuller: “With my associates I completed the design and study as well as a scaled-down model. The studies showed that the fabricating and operating costs were such that a floating city could sustain a high standard of living, yet be economically occupiable at a rental so low as to be just above that rated as the ‘poverty’ level by HUD authorities. The secretary of HUD sent the drawings, engineering studies, and economic analysis to the Secretary of the Navy, who ordered the Navy’s Bureau of Ships to analyze the project for its ‘water-worthiness,’ stability, and organic capability. The Bureau of Ships verified all our calculations and found the design to be practical and ‘water-worthy.’ The Secretary of the Navy then sent the project to the US Navy’s Bureau of Yards and Docks, where its fabrication and assembly procedures and cost were analyzed on a basis of the ‘floating city’ being built in a shipyard as are aircraft carriers and other vessels. The cost analysis of the Navy Department came out within 10 percent of our cost - which bore out its occupiability at rental just above the poverty class.” From the same site. ---
**Author:** ![Sam\_Stone](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Sam\_Stone](https://boards.straightdope.com/u/Sam_Stone)\ **Post date:** [May 26, 2007, 6:19am UTC](https://boards.straightdope.com/t/maximum-size-limits-for-floating-structures-water-and-air/405016/33 "2007-05-26T06:19:46Z")
Buckminster Fuller didn’t understand the huge forces that would be on such a structure in the lower atmosphere. What would a big wind shear due to a floating geodesic sphere? Or a hurricane? That’s why the big balloon I linked to above can only fly from orbit to a permanent floating platform that’s well above most of the atmosphere, and high enough that it’s immune to weather. ---
**Author:** ![commasense](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/commasense/32/3017_2.png) [@commasense](https://boards.straightdope.com/u/commasense)\ **Post date:** [May 26, 2007, 2:36pm UTC](https://boards.straightdope.com/t/maximum-size-limits-for-floating-structures-water-and-air/405016/34 "2007-05-26T14:36:29Z")
[QUOTE=Sam Stone] Buckminster Fuller didn’t understand the huge forces that would be on such a structure in the lower atmosphere. What would a big wind shear due to a floating geodesic sphere? Or a hurricane? [/QUOTE] I’m sure that Fuller understood weather and other natural forces just fine. Clearly there would be serious practical issues involved in actually building a floating bubble city. I’ve always thought of it as an interesting conceptual exercise, not a serious practical suggestion, unlike the Triton concept which was seriously considered for a while. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [May 27, 2007, 10:49am UTC](https://boards.straightdope.com/t/maximum-size-limits-for-floating-structures-water-and-air/405016/35 "2007-05-27T10:49:24Z")
\>please, define floating. “To move freely and gently in or through the air, as if buoyed up or carried along by it.” -Oxford English Dictionary [Previous page](https://boards.straightdope.com/t/maximum-size-limits-for-floating-structures-water-and-air/405016.md?page=1)