displacemant of a drum

Discussion in 'Boat Design' started by whitepointer23, Feb 9, 2012.

  1. whitepointer23

    whitepointer23 Previous Member

    how much weight can a 200 liter drum support. i am thinking if i was to make a pontoon type barge with 200 liter plastic drums, but i don't know what they will support.
     
  2. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    Assuming the plastic is close to neutral bouyancy, it will support 200 kg in fresh water, a bit more in salt water. Obviously you need more for a reserve, than that, of course.
     
  3. whitepointer23

    whitepointer23 Previous Member

    thanks, i thought it might be 200kg but i did not know if the shape had anything to do with it. we get a lot of empty drums that detergent comes in. they are quite thick walled and robust, i reckon they would make a great barge or house boat base. what would be the best way to lock them in position.
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    Plan on something that doesn't involve penetration of the drum. Strapping of some kind that can't slip off, that doesn't cut into the drums, and won't deteriorate in the water. Those drums cut in half would make a good tank to run an outboard in !
     
  5. tom28571
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    tom28571 Senior Member

    Actually your question is not quite so simple. The submerged displacement is easy but the displacement,or buoyancy of a cylinder, which is what you are probably interested in, requires some calculation. At half submerged its half the full amount but at any other draft you have to do some calculation. I don't know how much draft pontoon designers rate their craft at but I'd guess it is no more than half the diameter and maybe less.
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    Not sure what you are thinking here, but apart from the desirability of a reserve for additional load on the pontoon, the displaced volume will be the only measure of bouyant lift,(neglecting the plastic) though the level of immersion per unit of weight will vary according to how the drums are oriented.
     
  7. Submarine Tom

    Submarine Tom Previous Member

    Three things come to mind:

    Orient on their sides, lid high.

    Secure them well. If they roll the result is usually disasterous. I've seen it!

    Plan for 60% reserve buoyancy. That is, use enough barrels so they are only submerged by 40%.

    -Tom
     
  8. gonzo
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    gonzo Senior Member

    Those barrels are commonly used for floating docks and platforms. They work really well.
     
  9. whitepointer23

    whitepointer23 Previous Member

    would they need breathers, if fully sealed would they pressurise in hot weather or does the water around them keep them cool enough. we have winter temps of -2 to 20 degree celsius and summer 15 to 42. celsius.
     
  10. Mr Efficiency
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    Mr Efficiency Senior Member

    Wouldn't be a concern, IMO. Seal and forget.
     
  11. CDK
    Joined: Aug 2007
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    CDK retired engineer

    A drum closed on a warm, sunny day may partly collapse in cold water and loose buoyancy.
    There are also differences in air pressure to consider (nearly 10%), so it is wise to tighten the caps early in the morning when the drums are cold or pour a few drops of propane in first.

    There is a large fish farm on this island, using hundreds of polyethylene drums; the ones sealed in summer have large dents in winter, the ones that weren't properly sealed retain their shape but sucked in a lot of water and are almost submerged now.
     
  12. Mr Efficiency
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    Mr Efficiency Senior Member

    I'm thinking the shape of the drum would play a big part in any tendency to deform. A barrel shape would hold up pretty well I suspect.
     
  13. buzzlymutt
    Joined: Jul 2008
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    buzzlymutt Junior Member

    i live on a houseboat,floating on 200ltr plastic drums!my ideal when starting out,Drums were to be half submerged;50%.As above;Due to changing air pressure & temp;they are very good at loosing air,esp the ones in most sun.also ,Drums with the seam running thru the Bung hole,are likely to split(at the hole) if they've ever been overtightened.The best results in sealing,are ones that were sealed on a frosty morning,at the coldest time.Early winter here with the highest air pressure.on several lightly loaded rafts,drums give less trouble.
     
  14. whitepointer23

    whitepointer23 Previous Member

    can you post any pictures of your house boat.
     

  15. whitepointer23

    whitepointer23 Previous Member

    i was thinking of putting a breather in each drum with a bit of hose up the walls to keep the water out. you can buy those spear type fittings that go in irrigation hose.
     
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