My Grass Hut

Introduction.

The world is changing and I am not sure if it is for the better.  It flows around me like a high wall and I am sure that if I let it ..... it will simply flow over me and it will be ... as if ....  I never was.  So the plan is to build a grass hut on a dessert island and live happily ever after. Unfortunately I don't think I can afford a dessert island ... so I will have to make my own !. 

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I cannot remember where the barrel came from, except it found me in the middle of a high fever. In my delirious state I kept trying to push it away from me, but it always come back Hours later it was still there and I couldn't understand why. The barrel stayed with me for several days and in the end I wondered if it would float.

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You may be a little surprised to find that the 55 US gallon oil drum was invented by a very pretty young lady called Nellie Bly who patented it in 1905. I get a bit confused here because 55 US gallons   is equal to about 46 Imperial gallons. I am confused because I have spent a whole lifetime calling them "44 gallon oil drums" !.  I suppose the easy way out is to call them 200 liter oil drums.  

An anonymous oil drum !. This one speaks both English and Greek !.

Oil drum Sizes.

I once read that all oil drums are the same size ..... but they are not!.  So it will pay you to measure the ones you find !.  Two 'typical sizes I found were 24" x 34" (61 x 86 cm)  and 23.125" x 34.5". The empty weight varies between 32 - 36 lbs (15 - 16 kg).  Closed end drums are standard with one 2-inch NPT and one ¾-inch NPT threaded bunghole on opposite sides of the top head.  Immersed in sea water steel drums last about 5 - 8 years.  They are also available made of plastic.

Drum buoyancy or lift.

The amount of water a drum will displace is roughly equal to the amount of water required to sink it.  So a 55 gallon drum will displace 55 US gallons of water weighing about 440 lbs or .........  204 liters of water. Generally we want to aim at the unloaded weight of the pontoon displacing about one third of the above. This means that that about 8" of each drum will be underwater with the pontoon unloaded. If we decide that we never want more than 16" of the drum underwater, giving us 8" of freeboard then each drum will support 293 lbs or 133 kg of weight. Nine drums would give us 1200kg lift - the weight of the drums and supporting frame. Twelve drums would give us 1600 kg lift - the weight of the drums and supporting frame. You know how much one drum weighs ... so I will leave the rest of the mathematics up to you !

Tall Rafts .... flat rafts.

The sea water around the area I am thinking of is very shallow, so I need a shallow draft pontoon,  perhaps one barrel deep. The usual rule of thumb is one barrel for every person on the raft. On top of this is the weight of any superstructure to create the 'grass' hut, plus a generous allowance for windage etc.  One also needs to consider the 'floor area' of the pontoon.  In advance I want to allot at least 20% of the floor area for a 'veranda' at one end of the pontoon. Any thoughts as to a size for the pontoon yet ?. 

A modular approach to a floating home.

If we start off with too grand a design, it will fail on two points ... cost and practicality.  If we want a mobile sea home, it makes sense to break that home down into achievable modules. So the question is what is the smallest practical sized module ?. The answer to that is decided by material supply. If steel is only available in 6 meter lengths than we have to choose carefully how we use it, to avoid waste. If we intend to use oil drums as our flotation chambers then obviously dimensions may end up as a multiple of their length and width, Coupled with this, is the size of board material available and it is obvious that some careful thinking must be done to avoid expensive mistakes. 

Facilities.

Must be environmentally  friendly and locally acceptable..

It is assumed that water for consumption will be bottled. 

Must have bulk water supply for washing etc. 

Must have a local toilet facility that does not empty near the craft (Portaloo)

Must have refrigeration facility for small amounts of food and booze. (Gas refrigerator).

Must have means of heating during winter (wood burning stove)..

Must have means of generating hot water during both summer and winter months (solar heater).

Must have a shower facility. 

Must have a means of securing valuables against opportunist thieves. 

Must have means of cooling water during the heat of the summer (chatti).

Must have self contained power source for running small appliances (solar array + storage batteries)

Must be able to be easily moved onto land if required (winch). 

Must not require taxes or permits. 

Modular concept must  be expandable to suit any future need. 

Local acceptance.

The problem always boiled down to a structure that local authorities would accept. In Greece a stone structure would not be out of place. Yes, we could actually do a very good low weight imitation of that at low cost. For the same cost we can have the reed hut look. At the end of the day, it depends upon what one can gain official acceptance for. In mitigation it might help to point out that early houses would have used natural materials and that one such material is the tall reed that grows near to the sea on the islands. One thing is for sure, and that is if anyone doesn't like what I build then they can create a lot of problems for me with the authorities. Permits are required to do just about anything, and can be expensive or impossible to obtain. So part of my research will be looking for legal ways to circumvent existing legislation.  For example, all local boats are licensed, but do I need a license for a pontoon ?.  Can I fit an outboard motor to a pontoon to move it, or would that make it a boat ?.  Can I legally tow a pontoon with a boat etc., etc.. 

Another problem is that the authorities will judge the end product by what it looks like to them.  The fact that I want to live on it, may classify it as a house, or house boat ..... even though it is neither. Sanitation should not be more of a problem than it is for say a caravan or small boat .... but  the authorities may not see it that way. I have come to the conclusion that the only way to find out ..... is to go there and build one.  First to gain acceptance for the building of a 'pontoon'. I can consider adding the superstructure after I get over this initial hurdle.

First thoughts on the basic pontoon module.

Twelve  drums as follows ......

My first thought was for 4 x 4 drum layout, but I changed my mind for several reasons. First is that steel angle iron probably comes in six meter lengths. Three drums approximate to 3.0 meters long and four barrels can be adjusted to any width in the range  of 2 - 3 meters. Second was that I could add the veranda as a separate 1 x 4 barrel module. Third reason was that by keeping the size of the first basic module to a minimum, it might be more acceptable to the authorities and a smaller financial loss if it had to be scrapped. 

Development of the basic module.

I visualise a welded 3" angle iron frame, that sits over and contains the drums.  The drums will not be welded to the frame but secured to it by steel straps. This will facilitate repairs and drum replacement. The frame is shown in red.

The pontoon floor will be bolted to the frame giving extra strength. Will it be stable enough ?. Of course I already plan to add on a veranda module and that will greatly increase longitudinal stability. If extra living space is required then additional modules will be added and that will increase lateral stability.

Typical Material Weights

Black steel angle.

Black steel tube.

For any other steel size goto Parker Steels .

Marine Grade Plywood (8' x 4')(2.43 x 1.22 metres).

For other sizes and grades goto Robbins Timber

A stage further.

We are now in a position to approximately calculate  the weight of the proposed pontoon assuming a size of 3 x 3 metres. 

12 drums weigh                                                 180 kg

18 metres of 60 x 60 steel angle weigh               84 kg

Four sheets of 25.0mm marine ply for decking    140 kg

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                                                                       444.0 kg

If you remember 12 drums should give us 1600 kg of lift. If we assume two adults weigh 200 kg that still leaves nearly 960 kg of spare lift available, before we near the 8 inches of free board, I decided upon earlier.  The veranda will add another 400 kg of lift.  Looking good, so far.

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Styrofoam Buoyancy Billets.

It was the Dow Chemical Company that discovered Styrofoam in the early 1900's. The English better know it as expanded polystyrene. It comes in bead, granule and solid block form. The US coast guard adopted it as early as 1942 for a six man life-raft. More recently Dupont's have introduced an improved version for maritime use.  Available block sizes are as follows ........

The use of the Styrofoam billets provides greatly improved stability across the surface of the pontoon. As you can see Styrofoam gives three times the buoyancy per pound of material than an oil drum does. It also allows a treated wooden frame to form the pontoon shell, without the requirement for welding etc.. The skirts of the pontoon prevent UV degradation. Complete construction details and notes are available from .......

http://www.dockbuilders.com/dowdock.pdf 

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To be continued .......

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Pontoon boat notes (not for general consumption).

1.5 x 1 x 8' =  12 cubic feet

12cf  x 62.43 =  749 lbs x two floats = 1500 lbs   or 750lbs  for 9" freeboard.

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1 x 1 x 8' = 8 cubic feet.

8cf  x 62.43 =  500 lbs x two floats = 1000 lbs     or  500 lbs for 6" freeboard.

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