Houseboat weight

Discussion in 'Boatbuilding' started by boulty123, Mar 2, 2013.

  1. Scottym
    Joined: Apr 2013
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    Scottym Junior Member

    1000mm pipe will float 290 kg at 400mm submerged and 390kg at 500mm- absolute maximum I would ever think you would want to get to - after this depth there is less floatation for every mm deeper as the hulls are round.
    At 10m for a house boat and 3 pontoons this will give you a load capacity of 8.7 metric Tons- incl hull weight with an extra "live load capacity" of say 3T if you were anchored up somewhere and had 15 guests arrive as we have had!
    Plenty of weight carrying capability for something that is easily driven at 8 knots.
    The hulls will weigh 76kg p/m = 2300kg....maybe heavy in comparrison but the safety,lifespan and bullet proof nature compared to timber, fibreglass or aluminium is well worth this minor comprimise.
    you have 6.4T of capacity ie 6 people and 5.8T of building materials.
    More important and I think overlooked on house boats is roll stability...too many are too narrow and tall. Keep it wide for most comfort underway and at rest - 40-45% Width to length ratio both looks right and seems to work well. Putting a second story on needs close looking at!
    Keep your tanks in the centre pontoon either side of center ,maybe just slightly rearward, to minimse attitude and lean as you use water and add blackwater. Put in as bigger fridge as you can- it's the reason why you built the boat after all!
     
  2. srimes
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    srimes Senior Member


    I bet PE is the most common material that boats are made from today. Just look at all those rotomolded kayaks.
     
  3. srimes
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    srimes Senior Member

    Pics?
     
  4. boulty123
    Joined: Mar 2013
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    boulty123 Junior Member

    At last, someone talking from true knowledge. I had just about given up hope, not in my project, just finding someone with some straight and positive thinking.

    I was getting tired of the arrogant "experts" with their condescending manner.

    I should have guessed that another Aussie would provide genuine help.
    Thanks Scotty.
     
  5. Scottym
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    Scottym Junior Member

    Hers a couple of pics of the second set I made. Slightly shorter 9m ones.Same pipe diameter and set up for attatching to platform.
     

    Attached Files:

  6. Scottym
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    Scottym Junior Member

    No worries. PM me if you want any of the background info I have on the how to and the decisions I made before going this way. 5 years afloat now.
     
  7. CDK
    Joined: Aug 2007
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    CDK retired engineer

    The same pipe half submerged will curve in two directions. Both ends go down because of the difference in air / water temperature and the one facing the sun will also curve in a horizontal plane.
    It may not be a real issue as long as the construction carried allows for curvature and expansion, otherwise the boat will always stay noisy, doors may pop open etc.

    I used such pipes along the roof of an industrial building for both cosmetic reasons and to keep thieves from the roof after we had a series of expensive burglaries.
    On sunny days the pipe sections warped so badly the steel supports were torn from the roof, screws sheared or were pulled out, causing water intrusion. We finally solved it by making 5 meter sections, secured in the middle only, a 2 cm gap between the sections and a sliding support at each end. On sunny days it didn't look as sleek as it was originally designed, but it served its purpose.
     
  8. Scottym
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    Scottym Junior Member

    Yep you are right about the theory you describe in air- (and the pipe manufacturers supply all the expansion specs but also detail that for above ground it must be laid in ground or covered ) but in practice in the water is quite different. In a pontoon house boat situation 3/4 of the pontoon is covered by the boat top itself and the water and its surprising how cool the pontoons stay because of this.
    When building these and placed in the water there was no discernible curve in the vertical plane.On land the curve was max about 150mm horizontally but hardly at all vertically - and roasting hot inside the pontoon.. however once in the water the top stayed almost dead flat and inside was just above water temperature- and this was with out any top cover.
    I am not 100% sure why the deformation is so much less in practice but it takes a lot to heat 30mm thick HDPE and maybe the heat soak to the water and air inside overcome the heating and expansion effect.
    Maybe don't curve much in the water because the cool half resists the hot half?
    Anyway as with any pontoon boat ,the rigidity of the deck and the house structure itself is far more important - the minor stress by any heating is miniscule compared to the twisting forces imposed by the lifting force of a diagonally traveling wave! If the frame isn't built to withstand the twisting force of this you are on a raft waiting to breakup.
    Plus you can paint these exposed areas white of course! No doubt someone will point out you can't successfully paint HDPE....but in practice you can.
     
  9. tomas
    Joined: Nov 2012
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    tomas Senior Member

    Hello boulty

    Perhaps a company like this exists near your part of the world. "Wilson Pontoons", produces medium density polyethylene pontoons in 24 inch and 36 diameters. They are modular and are filled with closed cell polyurethane foam. They are also have a v-bottom as opposed to purely circular.

    Here's a link with construction examples:
    http://www.plasticpontoon.com/web/applications/index.html

    and this link for downloading product information:
    http://www.plasticpontoon.com/web/downloads.html

    This is not as inexpensive as building your own, but time is money also.
    Just an idea/suggestion for you to consider.
     
  10. whitepointer23

    whitepointer23 Previous Member

    Some experts have crashed and burned on this thread. Good shooting scotty. 1 question though. Where do you get pipe that large. I have only seen the smaller stuff around mine sites.
     
  11. BPL
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    BPL Senior Member

  12. Scottym
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    Scottym Junior Member

    Made by Iplex and one other company here but I found mine much cheaper by buying an "air dock" - so easy to cut off or fix up any openings in this material. I think aroun $8k per 12m length when I looked last to buy new.
    I did see some this size come up in an auction in QLD at one stage. They use it in large storm water projects.
    Called "flood pipe". Pressure pipe in the same diameter is thicker ,heavier and not needed for this use. Depending on size and number of pontoons either the 800/900/1000 mm would be my advice. I reckon you need 400mm freeboard as absolute minimum and pref about 500-600 ( which seems to be the same as most docks). If the boat isn't too heavy maybe the smaller of these would be ok and cheaper and look at 4 or 5 pontoons. an 8m boat using 5 x 800mm diam pontoons = 7T max at 300mm draft
     
  13. Scottym
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    Scottym Junior Member

    Haven't meant to shoot anyone down but wanted supply my research and 5 years in the water experiance for those who want to do the same.I must say that I really struggled to find a definitive answer to my questions when I started my search for using this stuff - its a new application and not traditional and in the end went with my gut instinct.
    5 years on and I cannot think of a better material for a houseboat hull. No electrolysis, no gel coat worries, no rot, park it on rocks, moor it in the shallow and let the tide go out, bash it beat it scrape it.Nada. All you need is a skill saw, electric planer, a 100mm grinder with a wood carving blade on it ....and a plastic extrusion welder.Thes are not cheap but would sell well once you have done your limited amount of work with it ....and if you can get your pipe cheap...... don't forget its green - HDPE 100% recyclable!
     
  14. whitepointer23

    whitepointer23 Previous Member

    Thanks for replying. I realise you were not having a go at anyone. It is good to read a well constructed post rather than the usual negative replys.
     

  15. pdwiley
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    pdwiley Senior Member

    What brand and how much was your plastic welder? Enquiring minds want to know (and maybe acquire yet another tool).

    I need some tanks welded up - a black water tank and 2 potable water tanks. Choices for potable water are 316, aluminium or HDPE and I'm leaning to HDPE. Black water, got to be HDPE or ply/fibreglass epoxy and I hate working with fibreglass.

    PDW
     
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