30' plywood sharpie

Discussion in 'Boat Design' started by davesg, Nov 4, 2009.

  1. frank smith
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    frank smith Senior Member

  2. kayaker50
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    kayaker50 Junior Member

    Troy2000, are you building a model? If so, I'd like to know how you make a scale model from scratch. Thanks, Chip.
     
  3. frank smith
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    frank smith Senior Member

    I have used thin plywood from the hobby store , makes it easy to lay out full size .
     
  4. troy2000
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    troy2000 Senior Member

    Very impressive. Of course, that's quite a bit more boat than I plan on building. But it's pretty much the same construction that I'll be using: sides wrapped around bulkheads.

    Um....well, I cut pieces to scale, and put them together like I was building the real thing. The last model of a 30' sharpie I built was 1"=1'-0", but it was a little small for working out the details. So this one will be 1 1/2"=1'-0". That means every 1/8 of an inch will equal one inch...which is going to make for a ridiculously large model, almost four feet long. I'm making it that big partly so I can do some reverse engineering and layout after I establish the basic hull: i.e., cut and fit parts, then measure them.

    Of course I'm working backwards, compared to people taking dimensions off a set of plans. Instead of taking an established overall size and shape and seeing what size parts it takes to get it, I'm arbitrarily setting the size and shape of the sides and the controlling bulkheads, and wrapping said sides around said bulkheads to see what I get. Then I'll modify one or the other as necessary until I'm happy with the results, and go from there with the details.

    I've built models strictly to scale from plans in the past, though. The first one I did was a Grand Bank dory from John Gardner's The Dory Book, years ago. I had a nice soft, even-grained piece of Ponderosa pine left over from some bookshelves, so I used my table saw and a planer blade to rip out a pile of scale lumber. Then I duplicated every piece in Gardner's plans, at 1"=1'-0". It was pretty much like working with balsa wood, and a whole lot cheaper.

    I also built a Caddo Lake Bateau and a few other models of small boats over the years, including several of my own design before I built the real thing. It's the same idea as a traditional boat or ship builder doing a half model to take the lines from, carried to an extreme.:p

    And the 45" model I'm going to wind up with this time? Sorry, but my boys aren't getting this one until I'm dead. I'll probably turn it into an r/c model. I'll have to add some ballast, and replace the pivoting centerboard with a larger, fixed keel for the sake of stability, since there won't be a scale helmsman on board with full-scale judgment....
     
  5. kayaker50
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    kayaker50 Junior Member

    troy2000, I for one would like to see pix of the model as it progresses. I like the idea of dealing with a real object instead of an image on a monitor. Chip.
     
  6. troy2000
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    troy2000 Senior Member

    I'll start posting as soon as I have something to show, Chip; I replaced my defunct digital camera this week for just that purpose. But it'll be a little while. I'm still waiting for a couple of Chapelle's books to show up in the mail, so I can study his designs first-hand before starting mine. Between Parker, Gardner, Monroe and others I already have a decent idea what I want, but it can't hurt to study the classic work boats Chapelle recorded.
     
    Last edited: Nov 13, 2009
  7. kayaker50
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    kayaker50 Junior Member

    Yes, I have Chapelle and Parker. A 27-30 foot sharpie is in my future too. Chip.
     
  8. troy2000
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    troy2000 Senior Member

    I feel about half-crippled; I'm used to having a full-sized drafting table set up to play on. I usually kind of bounce back and forth between it and models or templates, when figuring out anything from rowboats to trebuchets.

    But right now I'm spending a good chunk of my life working away from home and living in a motor home, and no longer have a 'man cave' back at the house. It's been overrun by the wife and sons for their own nefarious purposes, and that big old oak-framed drafting table 'took up half the room, and you never use it anyway..." So I'll be relying even more than usual on model-building for this project.

    I'm also looking at the layout of the motor home, though. If I bought a smaller, basic computer desk and ditched the recliner, I might be able to fit one of my old drafting tables in behind the driver's seat. It isn't like I spend much time entertaining anyway. Mostly, it's just me and a few beer cans.....
     
  9. gonzo
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    gonzo Senior Member

    Seems like you are in good company
     
  10. troy2000
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    troy2000 Senior Member

    Well, ratz.

    The two Chapelle books showed up in the mail, and they're chock-full of information. But the boat plans which were my main reason for buying the books have been shrunk down to fit book pages that are about six inches by nine inches. They're literally unreadable, even using a strong pair of magnifying glasses.

    I guess my only hope is to take them with me when I go back to work, and see if they're legible when I blow them up on the copier.

    If that doesn't work, maybe I can get the drawings elsewhere. Does anyone know whether the Smithsonian owns the drawings Chapelle used in his books?

    Better yet, are there coffee table sized issues of these books available anywhere, new or used?


    edit: never mind; I just answered my own question. I looked it up, and all the plans shown in the two books are catalogued in the Smithsonian's Ship Plan List (American merchant ships and small craft). That runs twenty bucks. I don't know how much the black line reproductions of the plans themselves are individually, but I doubt it'll kill my budget to buy a few of them. And it beats going blind, trying to study the miniature plans in the books.
     
  11. gonzo
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    gonzo Senior Member

    The table of offsets is there. With a flat bottom boat you only need a few points anyway.
     
  12. troy2000
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    troy2000 Senior Member

    I'm not looking at his offsets to build a boat; I was looking for a quick comparison of the hulls for such things as where the maximum beam is located, where the forward flat run starts blending into the midships rocker of the bottom, the height of the stem, etc.

    And I'm not kidding when I say I literally cannot read the plans, including the offsets--even using reading glasses much stronger than the ones I usually wear. They've been scaled down until the distance between perpendiculars for one of his 35' sharpies, for example, is 5-1/4 inches.

    The next time I head into town, I'll stop off at a drug store and buy a big magnifying glass. Hopefully, the numbering and lettering in the plans are sharp enough to be legible when they're blown up big enough to read. If so, I can probably blow them up with a good copier, and we have one at work.
     
  13. messabout
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    messabout Senior Member

    One of the most useful tools of the model builder is an architects scale. For those unfamiliar with such an item, it is a measuring stick with the marks and numbers reduced in various sizes. There are scales of 3/4, 1inch, 1.5 inch, 3 inch and sometimes you can find one with a 2 inch scale. With that tool you can lay out the model without much recourse to the calculator. Many office supply stores have the architect scales.

    If you intend to play in the water with the model you will need to see to it that you have scale weight. Calculating model weight is simple enough. Use the cube of the scale for a denominator of the weight of the full sized boat. If the scale you are using is 1.5 inches to the foot then the scale is one eighth. 12"/1.5" = 8 and 3" to the foot will make it quarterscale or one fourth. For one eighth scale just multiply 8 x 8x 8 = 512 Say the real boat is to weigh 2000 pounds....divide.....2000/512 = 3.90 pounds or 62.5 ounces. When building to small scale like one inch to the foot, the model is not easy to build light enough. One inch scale has a cube of (12^3) = 1728 and so that 2000 pound boat would need to be 2000/1728 = 1.16 pounds or 18.5 ounces. You can see that the advantage is for the larger scales. I usually build at either 2 inch or 3 inch scale and can therefore be less concerned about the weight of the materials that I use.
     
  14. gonzo
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    gonzo Senior Member

    I have those books and it doesn't seem so hard to read the plans. Make a copy and enlarge it.
     

  15. troy2000
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    troy2000 Senior Member

    Thanks for the info, messabout. I'm quite familiar with architect's scales; I was a general contractor for years, and drew my own plans most of the time for everything from patio decks to houses.

    But I've never tried to deal with calculating scale weight for anything fancier than a trebuchet counterweight before, and your explanation of how to do so is very helpful. Thank you.
     
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