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  #1  
Old 10-14-2007, 05:55 AM
gp1953 gp1953 is offline
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help with raft houseboat

Howdy All,
I'm in the process of designing a houseboat raft, simular to what could of been a shanty in day gone by. I have a chance of getting some plastic 55 gal drums for around 8 bucks each. Each one will displace around 450 pounds. My question is this if you were to stand them on end instead of laying them on their side would they be more stable? This raft would be around 15-20 foot wide and 30-40 foot long. I'm thinking of putting a geodesic dome on it to keep the center of gravity low. I would like to make it self contained and unflipable if that is possible under all conditions. So any advice or help in this matter of designing this will be greatly apericated.
thanks
GP1953
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  #2  
Old 10-14-2007, 10:05 AM
Busman1965 Busman1965 is offline
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drums

Very hard to secure drums in a verticle position. I have built a number of rafts with the drums horizontal, and they work just fine. I doubt it will make any difference on stability, at all. Just put them as far outboard as possible.
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Old 10-14-2007, 12:59 PM
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alan white alan white is offline
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The most stable method would not use barrels. It would be a steel or concrete basin (hull) that allowed the living quarters to begin below the waterline (perhaps this would be a couple of feet).
Any use of flotation from individual vessels such as barrels is going to make the underbody suseptible to rough underwater dangers, and also raise the CG at least by the depth of the barrels.
A steel barge hull with a flat bottom is probably ideal. It will have the least draft (and hence least liklihood of grounding), and the lowest CG short of a concrete hull. Barrels make sense under smaller rafts, but if a raft is large, a lot of money is going into accomodations, much more than into the hull. This is the reverse of a simple small barge.
A simple solution might be to see what large diameter (36"-48") steel pipes would cost. Two pipes would make a sort of catamaran, and the living arrangements could be slung between. Each hull could have an access hatch and allow painting inside.
But if you intend to do this for pocket change, with "whatever works", then the barrels make sense. Upending them ensures watertightness, but it will cause the CG to rise, increasing capsizability, though if the barrels are in two banks, leaving a big space between, the accomodations could nestle between and that would lower the CG.
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Old 10-14-2007, 03:06 PM
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The barrels would be more stable if horizontal, unless ballasted in the vertical position, which would decrease their floatation capacity. Of course draft would increase dramatically with a vertical orientation as well as the previously mentioned difficulty securing them to the house structure.

A box is the simplest of structures, if maximum stability and floatation requirements are high on the priority list. Steel, aluminum and plywood are the usual choices for these types of structures. Steel barges can be had pretty cheaply and with repairs can provide a substantial platform to build on. A plywood box can be built inexpensively and coated with a number of products to fend of moisture ingress. Truck bed liner may be an option here if coating costs are a concern. Another advantage of a barge like construction approach (scow bowed) is propulsion attachments are convention and they will do better underway and you can attach the house in a conventional manor.
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Old 10-14-2007, 08:14 PM
gp1953 gp1953 is offline
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Thanks for the input, Living in Kasas there is not a lot of options for building materials. Building the platform for the living quarters lower than the tops of the barrels if stood in a upright position would lower the CG. Running them in double rows across each side would provide more stabiltity? I was looking at putting a geodesic dome on the platform for low CG along with it being more airodinamic in case of high winds. Going with the dome would I make the platform a 6 sided like a stop sign? This would need to be livable for 6 months to a year depending on what goes down and then could be use to live in once removed from the water. Are there any plans out there for this type of craft?
thanks
GP1953
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Old 10-14-2007, 10:02 PM
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alan white alan white is offline
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A geodesic shape is pretty hard to make practical on a rectangular base like a pair of hulls. Why not use steel semi-hoops (similar to a a quonset hut profile)?
The semi-hoops could straighten just as they reached half-circle point and go straight down inside the barrels, to flat steel disc bases to which the steel is gusseted and welded, that sit at the bottom of the barrels. Barrel tops could be drilled for the frame and be slid up the frame sections before the steel disc feet are attached, then to slide down into place afterwards to seal the barrel tops.
That would make the barge an assembly of identical units. Each unit could also have cross spalls for the living space floor and a means of lengthwise attachment to tie all together.
Once on land, after the event you speak of, the barrels could be cut away and the discs would then sit on the earth.

Alan
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Old 10-14-2007, 11:38 PM
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Positioning additional the barrels vertically per support point will not make it more stable, just more buoyant, which could be an issue if you have too much and a house (of any configuration) sitting on top.

Do yourself a favor and calculate what your planed house should weigh including; structure, food, supplies, guests, everything, then you can make reasonable guesses at the amount of floatation and stability you'll need, with a margin of safety you can live with. In the end, floatation will be the least of your concerns.
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Old 10-15-2007, 12:24 AM
gp1953 gp1953 is offline
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The drums that I have available are plastic 55 gal. laying the drums on their side could be an option too. Each drum will displace about 450 pounds. I need to measure how long each drum is and then figure from there how many will be needed to place octagnoaly around a geodesic dome 12 feet across and around 10 foot tall. The barge raft houseboat will hold two people with enough supplies for 6 months to a year. If the dome has to be made larger to acomadate all the provisions and living quarters that would not be a problem, I would need to figure all that in before building the frame and dome. The quansan hut sound like a very good ideal too, using plastic drums would that be fesiable? The trick would be how to tie them into the barrels?
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Old 10-15-2007, 12:46 AM
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Quote:
Originally Posted by gp1953 View Post
The drums that I have available are plastic 55 gal. laying the drums on their side could be an option too. Each drum will displace about 450 pounds. I need to measure how long each drum is and then figure from there how many will be needed to place octagnoaly around a geodesic dome 12 feet across and around 10 foot tall. The barge raft houseboat will hold two people with enough supplies for 6 months to a year. If the dome has to be made larger to acomadate all the provisions and living quarters that would not be a problem, I would need to figure all that in before building the frame and dome. The quansan hut sound like a very good ideal too, using plastic drums would that be fesiable? The trick would be how to tie them into the barrels?
Well, I could see a system of building where a single round-section steel or wood trame curves across every four feet or so, then longitudinal members inside tie all the hoops together. Lately I've been noodling on the re-use of 275 gallon oil tanks. They are pretty easy to get (I got one like new from next door a couple of years back for $50.00. Then, just recently, across the street I scored a half-full tank with some pitting. I saved the oil to my house tank and I will make two firewood stands (one for me and one for sale) using 18" of the two ends of the tank.
But now I'm wondering if oil tanks (layed flat) might make a good basis for a cheap barge hull. You might need about 10 tanks for a 25 ft long dual hull.
You would have to repair some, and then weld around each joining face to create long hulls. Each would be seperate containers, so no leak in one would be a big problem.
A single 275 gallon tank would displace about 2400 lbs submerged and 1200 lbs half-submerged "design" displacement with a reserve of 1200 lbs.
This would give you a possible total displacement of 12000 lbs, or about 10,000 on top of the tanks, which might weigh 200 lbs each. Easily enough for being self-contained for a year.
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  #10  
Old 10-15-2007, 01:51 AM
gp1953 gp1953 is offline
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I would have to investigate that other option of the larger containers. i just know about the plastic 55 gal right now. I can get 25 for $200 which would be 450 x 24 devided by 2 would be close to three tons of top weight at $8 bucks each could go what ever it took to make this thing float. The quanson hut would give more room and could be made out of pvc pipe instead of steel pipe and the covering could be either metal or fobergass.
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