Pontoon

Discussion in 'Boat Design' started by Canveysteve, Oct 4, 2018.

  1. Canveysteve
    Joined: Jul 2016
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    Location: Canvey island essex

    Canveysteve Junior Member

    Hiya looking for help!
    I'm looking at a pontoon its a new build in 2017 it's made it's made of 18mm marine ply with three layers of fiberglass all over it the cavity is filled with polyurethane foam I've been told it's 55 ft by 16 ft wide and I believe it to be about 4 ft deep I've been toldtold he's able to float static caravan is this is this if so what do displacement will I be looking at any help gratefully received
     
  2. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

    Hello Steve,
    Are you trying to find out the displacement / weight of the pontoon as it is at the moment?
    Has it been in the water yet, re establishing a waterline where it floats?
    If say the draft is 1 ft, then the displacement would be approx
    (55 x 16 x 1) cubic feet = 880 cu. ft.
    One cubic foot of sea water is approx 64 lbs, so this corresponds to approx 56,320 lbs or 25 tons.

    What are you planning on using the pontoon for?
    Re the fibreglass covering it, do you know if this is made with polyester resin ('ordinary' fibreglass) or epoxy?
    Epoxy is an adhesive, hence this would 'stick' to the plywood much better than polyester.
    Was the plywood coated on the inside as well with resin before being filled with foam?
     
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  3. Canveysteve
    Joined: Jul 2016
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    Location: Canvey island essex

    Canveysteve Junior Member

    Hiya yes I'd in the water now not Shaw re what reisn was used or the ply was coated would that mater ? Will find out the water line adap it's to float a static caravan to be ueus as a house boat
     
  4. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    It should have plenty of reserve buoyancy that would easily be able to cope with carrying a caravan and perhaps a couple of large water containers as well (or will you be able to plumb into a shore water supply?).
    What is the asking price for this pontoon?
    Do you know if there are separate watertight compartments in the pontoon?If so, how many?
    It would be worthwhile trying to find out more about the method of construction - fibreglass over plywood is relatively 'cheap and cheerful', but it can lead to problems in the long run if the fibreglass delaminates from the plywood.
     
  5. Canveysteve
    Joined: Jul 2016
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    Location: Canvey island essex

    Canveysteve Junior Member

    Would have a water tank due to the water supply is pretty crap on a marina as far as I'm aware is solid foam so no compart the going will be going onto it is hopefully going to be 35 ft by 12 ft wide for sale for £16, 000
     
  6. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

    I am a bit confused - are there two pontoons, one 55' x 16', the other 35' x 12', and you are interested in buying the smaller one for £16, 000?
    Do you already have the caravan to put on it? If not, then that is an extra expense.
    Can you maybe post some photos of these pontoons?
     
  7. Canveysteve
    Joined: Jul 2016
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    Location: Canvey island essex

    Canveysteve Junior Member

    Sorry for the confusion the pontoon is 55+16 and the static mobile home is 35+12 can't seem to upload pics
     
  8. Canveysteve
    Joined: Jul 2016
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    Location: Canvey island essex

    Canveysteve Junior Member

    Well the pontoon has been sold now so that idai has gone !
    Ibc would they work ,foam filled to stop it colapcols ?
    Via the above calc 1200mm by 1000mm no cage they float around 5" in the water I'm coming up with 336lbs or 0.15 t per ibc is this correct?
     
  9. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

    I'm sorry Steve, but you have totally lost me now re your post above.
    If you like, you can edit your post to make it a bit more clear by clicking on the 'edit' button at the bottom of your post.
     
  10. BlueBell
    Joined: May 2017
    Posts: 473
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    Location: Victoria BC Canada

    BlueBell Ahhhhh...

    I think for Steve, a "Pontoon" is a type of boat.
    Presumably, this one has two pontoons or floats.
    Presumably, they are round in cross-section.

    Steve, if you could write in point form,
    one idea per line,
    it may be much easier to understand you.

    What is your question?

    One thing I'd like to make clear to you Steve,
    is that your pontoons should never be loaded beyond 1/3.
    That's well below the half-way mark.

    Thanks
     
  11. Canveysteve
    Joined: Jul 2016
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    Location: Canvey island essex

    Canveysteve Junior Member

    Sorry !
    The one I was hoping to buy has now been sold so on to the next Idea
    D
    Ibc /tote trying to calculate what they can take I'm currently living on a boat and am filling one with 500l of water ( no cage just the tank)
    Can anyone calculate the load it can take when empty it floats with about 5" draft they measure at 1000 mm by 1200mm
     
  12. BlueBell
    Joined: May 2017
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    Location: Victoria BC Canada

    BlueBell Ahhhhh...

    Sorry Canveysteve, your post is nonsensical to me, I can't help you.
     
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  13. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Senior Member

    One problem
    IBC are designed to resist a fluid pushing outward. When used floats, the water pushes inward. They often collapse!

    It is very difficult to sufficiently reinforce them
     
  14. Canveysteve
    Joined: Jul 2016
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    Location: Canvey island essex

    Canveysteve Junior Member

    Re the collapse id use a mix of bottle polidtipoli and pu foam
    To fill them

    The one I have now is with 500 L of water and is currently floating at the 500l Mark so would that mean one IBC could float 500kg (.5ton) if empty the 500 is about half way upthetank
     

  15. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Senior Member

    The metric system makes many things easier that the archaic system the US is determined to hang on to.

    1 L water weights 1 KG.
    So a 500 L container floats 500 KG less the weight of container and safety factors.

    50% is a typical safety factor for a pontoons. So 200 KG per 500 L container
     
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