Testing a design using cheap contruction dummy boat?

Discussion in 'Boat Design' started by parkland, Sep 27, 2013.

  1. parkland
    Joined: Jul 2012
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    Location: canada

    parkland Senior Member

    Hey everyone!
    I was just sitting at work the other day, and started thinking.
    For those of you that don't know, that can be dangerous, lol.

    But anyways, I got to thinking, as some of you know, I've been tossing and fighting with the idea of making a boat. Something big, but that can still fit on a trailer behind a pickup truck.
    Because I seem to be stubborn, and cheap, I really want a full displacement hull, which is almost non-existent on small boats. I'm after a small houseboat with small diesel inboard drive.
    I've had some good ideas I think, and some bad ones, which you all helped root out. At the end of the day though, here I am still thinking of welding a custom 1-off aluminum boat.

    So my idea was this:
    Build a "dummy boat".
    Build out of cheap OSB plywood or something, utility 2x4's, cover the outside with wax or something cheap and easy, and fill plastic barrels with water, to simulate the weight of the boats cabin and engine, etc.
    Barrels could even sit on pallets or something to simulate the height of the cabin.
    Fix an outboard to the back, and take it for some testing!

    Shouldn't a person be able to simulate a design this way?
    It would only have to last for maybe 20 hours of testing in the water.
    I expect would cost maybe 1000$ or so.
  2. dskira

    dskira Previous Member

    You right, you have some bad ideas
    you will be far better of to spend your money hiring a naval architect to design your boat.
  3. El_Guero

    El_Guero Previous Member

    Dskira is wrong and right.

    Your best bets are on a proa, a catamaran, or a trimaran.

    Best stability - be careful, they freak out when you mention the "p" word .... scares them.

    You can simulate what you want, but why spend $1,000's on a full size rig, when you could build a much smaller model, to see if you like the overall design the NA gave you? 8' to 16' should be more than enough for a scale model. Tow it behind a friend's boat ....

    Sharpies seem to be making a comeback for houseboat, riverboat, designs.
  4. Yobarnacle
    Joined: Nov 2011
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    Location: Mexico, Florida

    Yobarnacle Senior Member holding true course

    There is room for innovation in design.
    But as a very general remark, most options for hull shape have been tried.
    Since older hulls are plentiful and cheap, why not find one very similar to the design you want and modify it.
    Some closed cell foam bits glued on and faired and fiberglassed over will adjust minor differences.
    Might be best to find the USED hull of proven design FIRST, and then have an architect refine the design to your specifications, and draw the bits to be added on.
  5. El_Guero

    El_Guero Previous Member

    I like that idea, and it is GREAT for the environment ....
  6. parkland
    Joined: Jul 2012
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    parkland Senior Member

    That is a good point, if a hull could be found close to what you're after, just modify the changes instead of starting from scratch... Heck you could probably mock up some hull changes to a boat with just temp glue or duct tape, would last just long enough to try it out!
  7. nimblemotors
    Joined: Jun 2009
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    Location: Sacramento

    nimblemotors Senior Member

    I would suggest building a scale model if you are not sure and wanted to create something new or different, and have time to kill and need a hobby.
    If you want cheap, you'd want to get an existing boat to use.
    btw, A boat a pickup truck can tow can't be 'big'.
    Do you mean to say the biggest one a pickup truck can tow?
  8. parkland
    Joined: Jul 2012
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    Location: canada

    parkland Senior Member

    Yep, biggest you can tow legally.
  9. philSweet
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    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

  10. keysdisease
    Joined: Mar 2006
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    Location: South Florida USA

    keysdisease Senior Member

    Buy an off the shelf design that comes close to meeting your needs and build it once. Many stock plans come with options for wood/AL/fiberglass and some design supplier have forums where you can swap questions with builders on the same or similar projects.

    I may have started a new saying, like measure twice, cut once, only: Build it once.

  11. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    Parkland: No designs are started from scratch. NAs and shipwrights based their designs on previous ones. There are millennia of experience and data behind every new design. Re-inventing the wheel is not an efficient use of your time.
  12. rasorinc
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    Location: OREGON

    rasorinc Senior Member

  13. Petros
    Joined: Oct 2007
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    Petros Senior Member

    I have built a lot of small boats with salvaged lumber and scrounged junk. If you are itching to try out an idea building a "mock-up" is a good way to satisfy that itch.

    but go 2/3 to 3/4 size scale, it will save a lot of materials yet will be large enough to ride in it to get a good feel for it. Easier to tow and manhandle on the beach too. You can build it for well under $400 if you shop and salvage carefully, not counting the engine. Also look on Craig's list for used boating hardware and equipment for cheap.

    I would suggest using AC plywood and rip your own lumber from larger planks you buy at a big box store, also use exterior grade construction adhesive, or polyurethane glue. Put seven or eight layers of exterior grade house paint on it (you can get paint for next to nothing from the paint stores, ask for their mis-tinted paint or returns, they usually have bin of them they give you for free or at a very nominal charge like $1/gallon). Use the plated deck screws, they will hold up fairly well for several seasons.

    have a good time, post pictures of what you build.
  14. tom28571
    Joined: Dec 2001
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    tom28571 Senior Member

    Think about the possible outcomes of your quick and dirty project.

    1. It will probably not be quick but may well be dirty.

    2. If it turns out to be a bad boat, you will know what does not work but not what does.

    3. If it turns out to be a good boat, you have wasted a lot of time and money and have a vessel that is not worth anything and will die soon. This is the best possible outcome but will you have enough energy and support left to build the final version?

    4. Building a bad boat takes about as much effort as building a good one, often more.

    Full size cardboard mock-ups are good for interior arrangements but not so good for hulls.

    If you are determined on this course, it makes sense to use material good enough that you will have a decent boat when you finish. Difference in cost is not very much and the extra outlay will soon be forgotten. Nowhere is this more true than in the basic wood materials.

  15. Easy Rider
    Joined: Oct 2009
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    Easy Rider Senior Member

    I built this boat (9X28') out of plywood (very light) as a proof of concept boat. Used it as a real boat for almost 10 years. Had a great time w it, learned most everything I needed to know and had a great but limited boat for quite awhile ... while I was young. Made the trip from Juneau to Seattle and more. Cost very little even though I used marine ply held together w rescornal (sp? .. the purple stuff) glue.

    So I did pretty much what you intend and it mostly turned out very well.

    Since it's the only boat I've designed I thought it appropriate to use her name for my username here on BD.

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