Newbie builder question, help is appreciated

Discussion in 'Materials' started by Florida_Skiffs, Feb 21, 2013.

  1. boatbuilder41
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    boatbuilder41 Senior Member

  2. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The plans for the 16' Lumber Yard Skiff have 1/2" for the bottom and 3/8" for the sides. Adding bits and pieces here and there and making things bigger or thicker, thinking it will be stiffer and stronger is a classic engineering mistake. In most cases you just create stress risers and over burden the structure, which causes things to break.

    You'd be best advised to build to the plans. A thicker bottom is a feature I use in my skiff designs, but be careful what you wish for - ever try to bend a 3/4" sheet of plywood? All of my extra thick bottomed boats, use multiple layers of plywood, partly for this reason.

    I'm not sure how you'd make the Lumber Yard Skiff a V bottom, but considering your questions thus far, I'd suggest you haven't the hydrodynamic understanding necessary, to consider this radical of a change to the plans. No offense intended, but getting the balance right on a powerboat is critical, if you expect it to get up and scoot without any bad manners, when you grab a handful of throttle.
     
  3. tsmitherman
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    tsmitherman New Member

    PAR's answers are spot on.
    If this is your first boat, I would strongly suggest that you build it according to the plans. This will insure that you avoid all sorts of problems and that you will end up with a useable boat and not a pile of scrap wood.

    If you want a V-hull, then get plans for a V-hull - don't try to redesign a flat-bottom into a V-hull.

    TS
     
  4. Florida_Skiffs
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    Florida_Skiffs Junior Member

    So ur saying a .1 difference in side thickness will completely throw the dynamics off? I can settle for the flat bottom but ill be going 15 miles of the coast into the gulf and want it strong as possible, and it will be eventually powered by a 50 hp 2 stroke, i have a few ideas to strengthen the transom but what kind of hull modifications will strengthen the boat over all, my 14.5 fiberglass is terryifying in rough water, everytime i land from a wave going fast the sides flex like a kiddie pool. Try not to ruin my new liking for boat building with thing like it cant be done
     
  5. Florida_Skiffs
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    Florida_Skiffs Junior Member

    Priced out the whole thing from wood - paint - vhf and estimated it to cost around 1700, and thats rounding up on everything, however. I know how estimates go...
     
  6. Florida_Skiffs
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    Florida_Skiffs Junior Member

    The plans i saw on old warth suggest 3/4inch bottom and 1/2 sides, or is that for exterior grade
     
  7. boatbuilder41
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    boatbuilder41 Senior Member

    How big is the boat? L x w x h
     
  8. boatbuilder41
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    boatbuilder41 Senior Member

    What is the cost of just the wood?
     
  9. Florida_Skiffs
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    Florida_Skiffs Junior Member

    Ugh 15.4 x 6.6 x 1.6. Its the lumber yard 16
     
  10. Florida_Skiffs
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    Florida_Skiffs Junior Member

    800 dollars
     
  11. boatbuilder41
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    boatbuilder41 Senior Member

    If you got plans for it. Stick with the plan. Dont let me or anyone else get you off plot. I just thought i would list optional materials
     
  12. alan white
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    alan white Senior Member

    I'm not sure but it seems the problem with pressure treated is the high moisture content as it is sold. I haven't seen problems if the PT wood is dry. I've used stuff that had seen many years of UV as a house deck. The green color was very washed out looking at that point. I wouldn't use new stuff but I also wouldn't use any wood that wasn't at least 12% or so moisture content.
     
  13. Florida_Skiffs
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    Florida_Skiffs Junior Member

    Thinking of building the ob 15 now, The lumber yard isnt what i want with the flat bottom, I like the v hull, the chines, the weight, should be better for me and looks stable
     
  14. PAR
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    PAR Yacht Designer/Builder

    The problem with PT lumber and plywood is the chemicals now used. CA treated wood doesn't like epoxy much, unlike the former chemicals (CCA) that did get along with epoxy. The other problem with PT stock is it's usually of very poor quality. It is possible to get CCA treated stock, but you have to have a commercial business license and it's a special order.

    Big box store plywood is quite poor quality, even for a Lumber Yard Skiff. 1/2" plywood will be 3 veneers, the center layer will be full of voids, defects and other unwanted stuff. The exterior will be Douglas fir, which is difficult to finish smooth without a gallon of putty per sheet.

    A lumber Yard Skiff would do well with BS-6566 stock, such as Aquatech. You don't need BS-1088 on this type of boat. You would also do well with a set of plans intended for the type of use you anticipate. The LYS is designed for protected waters and putter around marinas, shallow water fishing spots and general utility. 15 miles off shore in the gulf is well outside the typical realm of the LYS's design parameters.

    Lastly about a small change in scantlings. you may think going from 3/8" to 1/2" isn't such a big deal, but what it is is a 25% different in thickness and weight. Again, as I mentioned, this is a classic engineering mistake and the LYS is more than stout enough in it's scantlings, as designed. Making it heavier, just forces the engine to work harder and decreases capacity and stability.
     

  15. boatbuilder41
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    boatbuilder41 Senior Member

    I hope the plans for either boat includes flotation foam if you arr going 15 miles off shore.bad weather in florida can appear in the blink of an eye.....trust me... i have been therr
     
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