beginner wants to build a boat

Discussion in 'Boat Design' started by GrandPixel, Aug 26, 2010.

  1. GrandPixel
    Joined: Aug 2010
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    Location: Florida, USA

    GrandPixel Junior Member

    I've been having ideas lately about building a boat. My search has led me to boatdesign.net forums. Greetings.

    I would like a large platform boat. My unexperienced boat-building imagination is picturing a bunch of large PVC pipe and some type of plywood-like floor. Then I would frame walls around the edge about 3-4 ft high.

    Should I use something other than PVC for floatation? What about the floor?

    Just getting started here and don't really even know the basics. I know that designing/building boats can surely be a very complex process, but I'm thinking that a large platform that floats should not have to be so complex.
     
  2. hoytedow
    Joined: Sep 2009
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    hoytedow Wood Butcher

    Welcome to the forum.

    Keep the first boat simple, perhaps skin on frame or stitch and glue.
    Keep it small, maybe to hold 2 people safely.
    Learn about fiberglass and epoxy.
    It is not that difficult if you take the time to read.

    Study the various threads on this forum.
     
  3. GrandPixel
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    GrandPixel Junior Member

    I did not mention the desired size of my floating platform. I would like it to be about 25' x 40' and hold about 50 people
     
  4. hoytedow
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    hoytedow Wood Butcher

    1 cubic foot of hull displaces about 62.4 lbs. of water. Do some calculations.
     
  5. ancient kayaker
    Joined: Aug 2006
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    ancient kayaker aka Terry Haines

    Sounds more like a dock than a boat. Go see what is available for building docks.
     
  6. apex1

    apex1 Guest

    With the PVC pipes and 50 people, you have a nice mix to learn something about jails in your region, you know?
     
  7. GrandPixel
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    GrandPixel Junior Member

    soooooo... any constructive feedback?
     
  8. jalmberg
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    jalmberg Junior Member

    Does this baby need to move? Like one of those pontoon party boats?
     
  9. alan white
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    alan white Senior Member

    You can call it a boat but it isn't. It's a dock. Learn how to build a dock. That information is already out there. Look at dock websites. 25 ft is crazy wide for any practical use. Half that would be more in line with something that can actually maneuver and fit existing systems for handling, hauling, and storing boats.
    I hope that's constructive but ask away if you need more help.
     
  10. MatthewDS
    Joined: Mar 2010
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    Location: Juneau, Alaska

    MatthewDS Senior Member

    It sounds like you want a float, not a boat. For something like that, you can get large diameter HDPE pipe, and build a timber structure on top. More common than that however, is a simple timber frame supported by coated polystyrene flotation billets.

    For a bit of perspective, a rough estimate to have a typical 25x40 foot float professionally built is around $100,000.

    edit:
    Here is a manufacturer of HDPE pontoon floats:
    http://www.hdpe.com/docks/Dock_Floats.shtml
     
  11. Vulkyn
    Joined: Jun 2010
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    Vulkyn Senior Member

    Right ... why on earth would u want to fit 50 people on a platform? and for what purpose ? Where will you use it? Why ?
    Did you choose the dimension based on something you saw or was it a random figure ?

    Still have a read through this thread should help shine some light on building a boat (if thats ur goal that is, wount help with building a floating dock i think)

    http://www.boatdesign.net/forums/open-discussion/dummies-guide-boating-stuff-33407.html#post382354
     
  12. DougCim
    Joined: Jul 2010
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    DougCim Junior Member

    Bah, so many crabby people around here. It's a boat, not the Space Shuttle.

    It's not a small start for sure, but many first-timers have built larger and much more complicated designs.

    .....PVC is very heavy and not very durable.... -and purchased retail, it's also not very cheap. I kinda cringe whenever I see the "how to build a PVC sailing cat" articles, I hope they had fun because anyone who did probably paid too much to build a dreadfully heavy boat. For a better solution, there's commercially-made HDPE floats you can get, or you can use HDPE pipe, or there's even HDPE barrels (used poly food barrels can often be bought very cheap from local food manufacturers).

    .....Neither is wood really, for this sort of application. Wood works for a normal boat hull because only one surface is wet, and you can smooth and seal that surface with epoxy or whatever. With a dock you have a big open structure, and EVERY exposed wetted surface would need to be sealed,,,, and even after that, it's gonna flex at the joints and crack the seal, and water will get in and rot it right at the joints. Forget the wood, use aluminum. And read about galvanic corrosion if this is to be used in salt water, else the stainless bolts will eat through the ends of the aluminum beams.

    .....A single-piece 25' x 40' platform would need to be built VERY thick, just to be stiff enough to keep from being damaged by wave action. I'd suggest making it in four sections that are joined by eyelets in their adjacent sides, so that they can individually flex with the waves. Floating plates cover the cracks in-between so you don't fall through when walking around. (As someone else pointed out, this is how large inland platform docks are made.... by joining several smaller platforms. USUALLY the individual platforms are small enough to be trailer-able, so that they can be hauled up the boat ramp for underside maintenance when it's necessary.)

    And also--people already done that.
    http://rollingbarge.com/floating-docks.htm

    FWIW, I don't know anything about building boats--but I have built other stuff, using a lot of different materials and machinery. If you gave me a budget and asked me to make a copy of one of these "rollingbarge" things, I doubt I'd have much of any problem.
    ~
     
  13. Raggi_Thor
    Joined: Jan 2004
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    Raggi_Thor Nav.arch/Designer/Builder

    Bathing floats are frequently built by lots of plastic cans inside a wooden structure. You need approx 100 liters or 25 gallons per person + some extra.
    I guess that's the cheapest way to go if you can find free plastic cans or barrels or something.
    I suppose, in the US, you get in trouble IF something happens to those 50 persons?
     
  14. Submarine Tom

    Submarine Tom Previous Member

    Sure! Have lots of fun and spend lots of money.

    Remember, safety first.

    -Tom
     

  15. Raggi_Thor
    Joined: Jan 2004
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    Location: Trondheim, NORWAY

    Raggi_Thor Nav.arch/Designer/Builder

    Doug is right :)

    [​IMG]
     
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