Sunday, December 27, 2015

A Ghost of Errors Past

Although I didn't know it at the time, I made an error in laying out BH-2 back in December, 2011. Good Progress

That error wasn't discovered and "repaired" until September, 2012. (Jan helped me spot my error then, too.) Measure Twice Cut Once

However, the real consequence of that error and repair - bad geometry for the King Plank - was not realized until now.

Various views of the King Plank mock-up today:
  • Overall view:
  • At the bow - a pretty close fit to the stem and the top of the stringer/plank structure:
  • In the existing notch in BH-2 (the real King Plank will terminate at BH-2):
  • At BH-1:
So, something needs to be done so the King Plank is fully supported. Filling in the notch in BH-1 is no solution, as the King Plank would stand much too proud of BH-1. Deepening the notch in BH-2 is the solution but the 2011 error and the 2012 repair mean the frame really needs some beefing up. The frame should be 200mm (4") wide before the 20mm notch is cut. The 2012 correction of the error left the frame only 78mm (barely 3") wide.

I'll cut the notch in BH-2 deeper until the King Plank is supported at the stem, BH-1 and BH-2. Then, doublers on both faces of the frame and a filler in between should correct the previous errors and strengthen BH-2.

Of course, now I can only wonder what other ghosts of earlier errors/repairs will appear as work proceeds on Gardens.
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7 comments:

  1. MoManDecember 27, 2015 at 7:49 PM

    When I asked JW about some of my own errors, he replied, "Look, this design is VERY tolerant of errors. Don't worry about them; fill it with epoxy, put some paint on it and go sailing."

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    Replies
    1. BobDecember 28, 2015 at 7:25 AM

      Thanks for sharing JW's comment. Excellent perspective to keep in mind!

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    2. BobDecember 28, 2015 at 7:25 AM

      This comment has been removed by the author.

      Delete
  2. S R WoodDecember 28, 2015 at 9:35 PM

    I had exactly the same error on my Pathfinder build. Subsequent swearing (much) and thinking (some) produced the following solution: split the difference; cut one notch deeper and shim up the other; reinforce as needed. I'm glad it wasn't just me.

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    1. BobDecember 29, 2015 at 9:02 AM

      Thanks for sharing - sometimes I think my mistakes are unique and mine alone. Good to know that isn't always the case.

      Splitting the distance is an option. I plan to enlarge the BH-2 notch a small bit at a time - no point in cutting through the frame if I don't have to...

      Delete
  3. DenisDecember 31, 2015 at 12:10 AM

    Hi Bob, one consideration when choosing a height for the king plank is how the ply deck will wrap over the glued up assembly. Not having a ply deck ( strip plank) allowed me to blend my errors into my mistakes and all was well, but from what I've read, plywood is not as easy. Hope is all goes well in the boat cave, (it's 44 degrees C in mine today).
    Happy and safe new year..

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    Replies
    1. BobJanuary 1, 2016 at 8:15 PM

      Thanks for the reminder. There will be pondering involved in installing the king plank. From what I observed yesterday, there isn't a clean and simple installation that doesn't require some a bit of work to accommodate the ply decking. I'll be careful.

      Delete

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