What construction method was used on this boat?

Discussion in 'Wooden Boat Building and Restoration' started by Tiny, Jan 7, 2009.

  1. Tiny
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    Tiny Junior Member

    I dont know a massive amount about wooden boat construction, so please forgive me if this is a really dumb question...

    I'm curious about the construction of the boat (a cruiser racer) in the attached photo. I'm sorry the detail isnt brilliant.

    The planking is approx 60mm wide, sapele I think. I assume glass or veneer on the inside of the hull for cross grain strength.?

    There are no noticable filled fixing holes to where temporary frames would have been, so how would planks have been fixed during bonding?

    Or am I totally wrong and its stringer-frame with plywood.

    Can anybody fill in the detail please?
     

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  2. PAR
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    PAR Yacht Designer/Builder

    That looks to be a molded hull. It's made of thin veneers of wood, over a mold, often vacuum bagged into place as the glue cures. Several layers of wood, typically running at alternating angles to provide cross grain strength, are glued together. On this one and commonly done of brightly finished hulls, the outer most layer is run fore and aft, though the other layers will be alternately about 30 degrees to perpendicular. This is one of the lightest ways to build a wooden hull.
     
  3. M_Star
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    M_Star New Member

    Maybe a faux wood

    Is it possible this is a conventional fiberglass or similar material with a faux wood finish applied? There are systems available to make almost any non wood material appear as wood. Some people are so good at applying these faux finishes they are labeled professional artist. Sometimes they will use similar techniques to produce a marble affect.

    Today's technology is touching every field, including paint and finishes, not just computers and electronics.
     
  4. alan white
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    alan white Senior Member

    The chance that this is a glass boat with applied wood, either fake or real is microscopic. Not only have I never heard of such a thing, but I know well how difficult it would be to achieve such a surface treatment, only to watch it deteriorate from UV rays until it becomes too expensive to keep up any more.
    No, this is surely as PAR said it is: a cold molded hull like so many others.
    Even the solid wood veneer, which is quite thick compared to a faux finish, is a lot of work to maintain, and if it were mine, I might just leave the transom bright and paint the rest of the boat.
     
  5. Boston

    Boston Previous Member

    I can tell you its not plank on frame
    way to smooth for that
    I think cold molded is a good bet
    or it could be a dam good Ashcroft method

    cheers
    B
     
  6. PAR
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    PAR Yacht Designer/Builder

    It's possible it's a faux finished boat. A few manufactures are using this technique now. One give away is the "step and repeat" pattern of the wood grain that doesn't appear on the image shown. Most samples of this "printed veil" 'glass fabric used in the faux applications, has a repeating pattern about every 48" and the grain (if chosen wisely) is rift, as to not make this pattern obvious. The image above has a lot of wild and flat grain in it, plus obvious seams every fourth plank on a common axis, which wouldn't be in a faux finish.

    Ashcroft would have a diagonal planking pattern. If an additional layer was added to Ashcroft, to make a fore and aft planking run, then it would become a true molded build and decrease the benefits of the Ashcroft method.

    It could be double planked as well. I've seen carvel hulls this smooth, but you don't see this quality of carvel building any more and there aren't any visible caulked seams. If it's double planked, it would explain the seams every fourth plank on a vertical axis. I can't see enough of the hull to tell if this continues further up the hull. This is a lot of trouble to do on a molded build, but I've seen some that did it.

    I still think it's molded because there aren't any visible bungs, or they're very well matched, which seems unlikely.
     
  7. Tiny
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    Tiny Junior Member

    Another picture

    Gentlemen, thanks very much indeed for your replies. It would seem that the consensus is that it is a moulded hull. I have included another picture which shows detail slightly better.

    I do believe she is a light and stiff hull, having raced against her I seem to remeber she was fast for her rating.

    I dont believe it is a faux finished boat, becuase (and this is not clear in the picture) as the planks/veneers curve round towards the keel near the transom they are just as one would expect if they were planks/veneers.

    PAR is correct, there are no visible bungs, well matched or otherwise. I couldnt see evidence that veneers have been temporarily stapled in place prior to bagging, but the holes would have been small.

    What I still dont understand is, if it is cold moulded, wouldnt one choose to use strips of veneer wider than 60mm and reduce the work load?

    I estimate the boat is 15 years old, the hull is in near perfect condition. With cold moulding is there not a good possibility of ripping through a layer of veneer whilst sanding back, and this in general making the boat difficult to maintain?
     

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  8. Guest62110524

    Guest62110524 Previous Member

    she looks like Heaths Condor cold molded maxi ex Whitbread race Conor of Bermuda renamed, went up on reef, with Aussie skipper years ago
    others were Golden Apple Of The Sun, Ron Holland Admirals Cupper laid up the skins totalled one inch, cat remember 3 or 4 layers mahogony
    see I have been around for ages
    anybody who suggested ply , really well shame!!
    Condor was salvaged, skipper fired,
    beautiful way to construct a yacht, google up Apple Ron Holland, cruised with her in 1981 in New Calidonia
    In NZ still do it this way although not well accepted eleswhere in the world Tightest timber method there is
     
  9. PAR
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    PAR Yacht Designer/Builder

    Wider planks can cause edges to curl as they are twisted to shape over the mold. 60 mm planks can be cut from less then ideal stock, cutting around defects, which would have to be included in wider stock.
     
  10. Guest62110524

    Guest62110524 Previous Member

    thats why the first two and sometimes the third layers are planked diagonally around the body
    besides all of these were built using CLEARS when timber, the mahogonys were more readily available
    the biggest majority of diagonally planked boats were glassed
     
  11. PAR
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    PAR Yacht Designer/Builder

    They were planked diagonally because of longitudinal grain orientation and the ease of bending the stock on without excessive shaping or torture. The fore and aft arrangement is purely an aesthetic consideration. All molded hulls will have diagonally orientation of the planks, 90% of the time these will be opposing in subsequent layers. Some methods, such as Ashcroft and double planked will have same direction orientation, but they are weaker for the same shell thickness.

    Molded boats have been around for a few hundred years that I know of, so the vast majority of them wouldn't have been 'glassed, though modern versions of this method will have been, for abrasion resistance.
     
  12. Boston

    Boston Previous Member

    back in neolithic times when I was out on the cape we did several cold molded hulls
    another benefit to them is that u can use less than perfect pieces in the inner layers saving your best pieces for the finish

    its a bunch of resawing though
     

  13. Tiny
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    Tiny Junior Member

    Thank you Gents, I am enlightened.
     
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