making a concrete 50' diameter 1/2 sphere boat hull – Ideas
August 23, 2011 at 1:08 am #1602
I am looking for ideas on casting a 50′ diameter 1/2 sphere of concrete 12″ thick in one large pour so it will have no cold joints. the concrete would use PVA fiber for reinforcement and no steel. – please lets no debate about if its a good idea, or who would want it, because I do… I would like to find a way to semi mass produce them, ie someplace near the water on on the water that can be disassembled and reassembled something to be replicated… cost reduction is in mass production.
It would weigh in at about 250 tonns for just the concrete
Any constructive ideas?
my personal blog / forum – http://OutpostAlpha.comAugust 23, 2011 at 2:27 am #14852
i agree with the weight. it sounds consistent with weights that i’ve been calculating. i really dont have a clue, personally on how to form concrete. especially complex shapes. i know there has to be info out there. keep us informed.
“Leadership and do-ership are not the same thing”August 23, 2011 at 3:26 am #14854
I really like the idea of a heavy sphere 1/2 as a cast concrete hull, and the top 1/2 simple 2″ tube steel geodesic structure, with whatever covering you want to add, sunshade, tarp, boat wrap, fiberglass, plexiglass or a combo. Build concrete walls like a honeycomb inside the bottom 1/2 and a concrete deck over the top and put in watertight doors all over, potentially decks below and then ballast below that, im thinking the 1/2 way mark may be 8-10′ below the centerline of the sphere. I think it would make a very sturdy and impressive structure.
The key is to be able to make more than one to develop them back to back to back like a production line. Simplicity and most of all uniformity so replicating will be easy.
Idea 1) I am initially thinking steel plate in geodesic triangles bolted together as a forum then gunniteing on the inside bowl. After casting is complete unbolting the steel panels and you essentially would have a large concrete bowl sititng on the ground. use loaders to push, roll, and wobble it into the water. variation possibly make the steel structure floating in water already so you dont have to move it only use divers to unbolt the lower panels to reveal the concrete.
Idea 2) Digging a pit or building up a sand pile and sculpting out a form like doing a swimming pool then water saturating the hole to float it up a bit and crane it out, it would take a monster crane probably too expensive.
Idea 3) Casting individual trangle shapes that interlock and bolting them together with steel polts and giant plates / washers to even out the load bolting and caulking 1 piece at a time.
comments?August 23, 2011 at 3:42 am #14855
George have u done calculations to find exactly where the water line will be? once u have that its just the beginning, then u have to add weight for the dome on top, interior walls, plumbing electrical, appliances furniture and a bunch of extra… then where does the water line hit? based on my previous work i have a strong feeling your water line is well above the rim of that bowl. and if thats the case, trying making it thinner. i use 8in (0.2m) wall thickness for my bergsteads.
and when it comes to the details of how to actually build the structure, i wouldnt worry too much about it. u see when an idea sparks the interest of some real investment money, modern industrial civilization has ways to materialize things that u might not expect. my opinion is to focus mostly on the product and make sure it’s something that can find a market – above all else.
“Leadership and do-ership are not the same thing”August 23, 2011 at 6:48 pm #14864
If I had all the resources, I would build a sturdy steel form of a 50′ hemisphere with smooth-welded interior seams.
The concrete mix could be dumped into it in quantity that’s more than enough to fill out the form.
Then, a crane could drop in a similar steel hemisphere built on a 48′ diameter and exterior seams to flatten and distribute the concrete between the two hemispheres.
The 1′ wall thickness spacing can be maintained by affixing a 1′ long thick steel pipe, as by breakable wire, to the nadir/trough (opposite of zenith/apex) of the inner form to keep the inner form from being inserted too far. Once outfitted, this pipe can be cleaned out of concrete and threaded on the inside for use by the ballast system. Regulation of the 1′ wall thickness around the perimeter where the edge of the concrete will remain exposed would be trivial.
An issue would be the buoyancy of the inner form’s steelwork, floating in the concrete mix, so being inserted too far is not a really big risk. The suspension work between the inner form and crane could have additional weights on it so that the crane can lower them progressively to use them to apply sufficient weight on the inner form to insure it fully seats in the outer form and concrete.
Then, there should be strong electric or liquid fuel vibrators attached to the inner and outer formwork to apply sufficient vibrations to insure the concrete mix fully fills the form, adding additional concrete around the perimeter as needed.
More likely, the perimeter will need the excess removed, so the outer form’s perimeter should have an outer trough from which additional concrete can be collected to top off the concrete shell and ultimately all the excess can be collected and reused to minimize waste. At this point, any hard points and other fixtures needed to anchor the superstructure to the hull can be embedded in the perimeter of the concrete.
Any interior concrete features can be moulded into the inner form, but, of course, any lower concave surfaces would have to have channels in the inner form that is filled with a filler device held firm for initial filling, but which can be released for the inner form’s ultimate removal, perhaps wood blocks with through-bolts. Those protuberances would likely need someone walking in the inner form’s steelwork with a portable vibrator to insure that they are also properly filled with concrete.
Once the shell has cured sufficiently, the crane can hoist it out of the outer form by the inner form, and swing it over to a place where it can be floated and the interior form released
Fill with interior structure resting on those moulded protuberances, and outfit as desired.
Somewhere, there should be provision for a propeller(s), rudder(s), and directional thrusters for motive force and maneuvering.
I have a thorium reactor under the hood of my car. I get ∞ miles per gallon.August 25, 2011 at 1:26 pm #14862
I want to focus on how to build the 1/2 sphere not weight and balance issues, it distracts form th eprimary goal…
Your going to have the same issues facing development weather you have a 6″ 8″ or 12″ hull thickness…
I want to come up with a practical method to build, then you can look for investment money to make it happen, otherwide your just chasing your tail around.
at 12″ thick a 1/2 speres would come in around 500k lbs and the water displacement capacity of the 1/2 sphere would be approx 2 million lbs… so 500k lbs of building and accessories would still only sink the hull to its 1/2 way mark by volume. The point to have concrete walls vs wood walls vs foam walls or babboo for that point is trivial, its not the issue, the issue is how to construct the shell as simply as possible so we could actually have a real product not just dreams.
so back to how to construct please…
my personal blog / forum – http://OutpostAlpha.comAugust 29, 2011 at 5:47 am #15043
Check out Monolithic Domes. They’ve already done half the design work for you.
For reinforcement, consider fiberglass or basalt.
If you wanted, you could even use this method for the structure part of the superstructure – simply leave plenty of openings for doors and windows.September 21, 2011 at 8:47 pm #15601
Concrete dome homes can be made out over 50′. One method they use is air bags, but I am not sure they could hold weight of 1ft walls. If they can maybe create a 3″ think wall let dry then add the last 9″ (just picked numbers). Most domes I have seen have alot of rebar in them.September 21, 2011 at 11:15 pm #15604
thats a neat idea. pretty smart. im wondering what the berg is for in that profile pic. prob another smart idea.
“Leadership and do-ership are not the same thing”October 4, 2011 at 2:05 am #15742
I would agree with shreder about were your water line will be. You could extend your outer center by eight to ten feet up before you add the top dome. At least in calmer waters you wont have water slapping up on your dome. I am not sure why you want so much material for weight. You limit the distance you can come to land. A sphere has no surface area for bouencey. You can experiment with a plastic fishinhg float sphere. Drill a small hole in the top and slowly add liquid weight to see were your water line goes to. You might reduce the thickness and add an exterior of glass or metal and the same for the inner wall. You could use the wagon wheel design for inner support and strenght for each level. You could increase or decrease your weight with a ballast system using seawater. Either way you may need several molds, to put together one unit. There are all kinds of ideas you can use with a sphere design. Do not forget you may need an opening/area for a small boat or zodiac.Not sure what your vision is, these are just some thoughts.October 4, 2011 at 2:25 pm #15752October 5, 2011 at 1:09 am #15755
Ellmer, the concrete shell design is one of best designs I have seen. One of my drawings is simular, but I still added more height between the water line and the upper dome to prevent some of the waves slapping on deck.as the video showed. Another note,even weight ditribution will help bouyency. Actual at sea steading is going to be alot different than steading in coastal waters. If steading is staying in one place, I think it will be hard for a small unit to stay in one place at sea 100 miles out. Especialy when 30 to 50 foot swells come your way. Have any sea goers on this forum experienced riding a swell? This design would be great for starting point with submersibles. A larger scale ,selfsustaining,submerged for six months or beter would be a great starting point for space travel/colonizing.(submarine style).
The problem I see with humans and sea steading at sea is we are born land dwellers. The ideal situation I think would help this project would be a generation born at sea or water enviroment. Some of that generation should be able to handle an isolation enviorment such as under water colonizing/space travel/space colonizing. It takes certain individuals to handle months to years of sea life., much less a family. Many more thoughts.October 5, 2011 at 9:33 pm #15763
sam7, the submerged living space bubble emerged as a concept (see earlier discussion here ) when it became clear that waves in open ocean can build up to almost arbitrary height and it happens about 5 times a year that a 20m wave can come out of nothing in a 4 m wave ambient. (Draupner New Year wave video )
(The Draupner wave, a single giant wave measured on New Year’s Day 1995, finally confirmed the existence of freak waves, which had previously been considered near-mythical. – see more here)
This brings up the need that ANY structure built for survival at sea that does have less than 15 m freeboard must be designed to be overwashed and submerged sometimes. So logic leads necessaryly to two development axes, enormous structures with more than 15m freeboard that can take draupner waves, or structures similar to a survival pod that can be submerged.
Even a structure like a Bulk Carrier has to be built to be overwashed and submerged sometimes: (see video bulk carrier in violent storm overwashed)
While a ship needs to be built to fit into a existing harbor and load terminal infrastructure, a open ocean capeable living space can be built to be semi, part, or completly submerged what takes all wave hazards out of the picture.
There is a good reason why mother nature never developed a open ocean capeable surface animal or plant – the surface is a biological desert it is too violent to allow bio settlement. Oceanic animals live below the surface or fly above it.
When colonizing the ocean we should think in doing it in a similar way.
Also see disaster proof house: video lens habitat floating and testing
concretesubmarine.comOctober 5, 2011 at 9:39 pm #15764
Seems like the best way to do it, is find a narrow , long inlet, with about a 30 meter depth opening, and up to 60 meter mouth. Would be best if it is rock outcroppings on both sides, so you could build roadways down each side.
Order one of the inflatable dams they use for flood control and urban lakes. Inflate it in the mouth of the inlet, pump out water. In the sand bed on the bottom, form out the shape desired.( i would use a sea turtle shell as a design, it has worked for couple million years ) spray in a foam laminate to fix the shape, and serve as a bumper later. Now shotcrete down a foam ceramic shell to serve as a structural form for the foam concrete. blow in about 3 inches of foam ceramic, let it cure, then blow in 3 in of foam cement. lay down some woven pre-stressing cable for later tensioning,some precast rigid ceramic spines for stiffness (prob on diagonal overlaps) some pvc electrical conduits, and a couple 4″ pvc pipes so you can pump ballast in and out of the bottom, or load one side of the structure (into the wind/waves) for stability in high seas. Now bring in your interior form panels, from preconstructed foam forms on the beach.
I would use this type if you want interior sea water processing facilities ( such as for lithium and magnesium recovery), as it is so easy to form openings beforehand, and it wil also be the dominant surface structures anyway. might as well get proficient with it. You will want to have many, rather than one big one, for privacy, specific sheds, and to keep center of grav low.
or you could just build steel shell forms in the same design if you were going to make many. The benefit of building the steel shell, is it will help hold the higher psi concrete in its shape if you want to pre-stress them. Now you DID remember to connect all those cables to a ring in the bottom, right ? That ring should be connected to a giant eyelet sicking out the bottom. That will be used as a sea bottom anchor point if you want to stay in an area. That stress loading on the anchor cable can easily be converted to piezo and tidal electric conversion, and water pumping. also might be a good idea if you had an outer ring cast in , so you could attach exterior bumper ribs for coast /coral and connections to other foam domes. Better coat em with ceramic foam to keep down oxidation and other corrosion.
Once you have the outer shell, structual ribs, and electrical conduits in, drop in the forms of choice, and pump in some higher psi concrete. Prob be able to hook up regular concrete vibrators to the cable ends, you WANT it to bond to the cables after all, You should probobly pump hot water thru the pvc electrical pipes at this time to heat cure the high psi concrete. Pull the forms, and shoot on another layer 2-3″ layer of ceramic foam for rigidity and fireproofing. Drop in a puddle shaped balloon/airbladder, and hook it up to some actuator valves, pumps, and the 4″ pvc pipes for ballast control. this will be the ballast tank, and the bottom floor of the foam dome.
Now start putting in interior wall forms, design dependent on commercial or residential . Remeber, there should always be SOME residential sleeping quarters down here, at the center of gravity is the least rocking in a storm, and may be the only place to get some sleep in a major storm.
You will prob need at least a quad, and prob prefer six radial walls to the perimeter, to hold it steady as you prestress the interior cables, and to spread any compressive loading from one side to the whole structure. Extra interior walls also make more waterproof compartments, so will be a trade-off of weight vs. safety .
Once you have the interior shaped, and the internal walls, floors, and central spire up (you are putting in a central spire for cooling below decks, a target for focused solar thermal up top, a lookout, and cable anchor for shade/solar/gardening) you should prob start digging out sections of the sand bed below to attach those exterior ribs and then, when you have worked your way around it, pushing and digging sand, pile it up at the rear of the turtle shape, and form in a dock, and a engine mount (optional). (prob gonna have to form in a mermaid out front to balance that).
Deflate the inflatable dam, and your drydock form fills, and you can tow the TurtleBack foam dome out to accompniment of champagne bottle salute (organic, of course !)October 5, 2011 at 9:54 pm #15765
Guess i should have laid the external spars, and the bottom eyelet in the sand first , but it came to me as is was thinking about stressing the concrete. then as an energy generator and water pump
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Written by georgeberz