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Thread: More Hartley

  1. #176
    Join Date
    Jan 2017
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    RAT Beach, CA, USA
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    276

    Default Re: More Hartley

    Quote Originally Posted by Small boats rock View Post
    Perhaps use some of your three ply to make a test scarf joint. After it is well cured try to break it. You may be surprised at how strong the joint is, or if not then at least you know to look further for other ply wood.
    That sounds like a good idea, you know what they say about assuming...Thanks Geoff. I also need to figure out how to cut the 12:1 taper on 1/4" pieces...any ideas out there?

    Quote Originally Posted by Hugh MacD View Post
    And perhaps give it a "boil test" to see what kind of glue they actually used. I had some "exterior" ply (5/8" 5 ply) offcuts that I got wet and they didn't just delaminate, they fairly flew apart. I was just using them for a benchtop, luckily.
    Ouch! another good test for my assumptions Hugh. By the way I went back to the homeland in the Willamette Valley last weekend, I sometimes forget about how beautiful the PNW is.

    Anyway, thanks for the thoughts and opinions, always looking for more!

    Eric
    Oh, ain't it amazing all the people I meet?
    Got a revolution, got to revolution
    One generation got old
    One generation got soul
    This generation got no destination to hold
    Pick up the cry

    Marty Balin and
    Paul Kantner

  2. #177
    Join Date
    Sep 2005
    Location
    new zealand
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    3,080

    Default Re: More Hartley

    Butt blocks are alternative to scarphing, and work just as well. Use the same plywood as your planking.
    FWIW, when I built the CLC sea kayaks, that was all 4mm 3 ply, and it scarphed fine - just keep the joints away from the areas with a lot of twist, they'll be fine.
    On the Pathfinder, everything below seat level (out of sight) was butt blocked, everything above was scarphed. Butt blocks don't have to be butt ugly either, you can fit them neatly between stringers, and radius the exposed edges.

    Pete
    Don't underestimate the power of stupid people in large numbers!

  3. #178
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    Default Re: More Hartley

    Quote Originally Posted by epoxyboy View Post
    Butt blocks are alternative to scarphing, and work just as well. Use the same plywood as your planking.
    Pete
    Good point, in fact butt joints with a backing plate is the method shown on the plans for the trailer sailor...
    Oh, ain't it amazing all the people I meet?
    Got a revolution, got to revolution
    One generation got old
    One generation got soul
    This generation got no destination to hold
    Pick up the cry

    Marty Balin and
    Paul Kantner

  4. #179
    Join Date
    Jan 2017
    Location
    RAT Beach, CA, USA
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    Default Re: More Hartley

    Greetings all,

    Small steps lately, but just finished up with a lot of detail and the diagonal stringer needed to place all of the rest of the stringers.

    DSCF7233.jpg

    Quote Originally Posted by Hugh MacD View Post
    And perhaps give it a "boil test" to see what kind of glue they actually used. I had some "exterior" ply (5/8" 5 ply) offcuts that I got wet and they didn't just delaminate, they fairly flew apart. I was just using them for a benchtop, luckily.
    I've been thinking about this idea a lot and have decided to embark on an investigation that will hopefully save some $$ and give me some practice with plywood scarf joints. Big question is: Can exterior plywood be used in lieu of BS 1088 plywood? 3 ply vs. 5 ply gives me cause for concern in the connection and the boiling test is very important as well.

    Not that I believe I'll sail into a boiling sea for any measurable piece of time.

    New thread to discuss exterior plywood: http://forum.woodenboat.com/showthre...07#post5623807

    More later,

    Eric
    Oh, ain't it amazing all the people I meet?
    Got a revolution, got to revolution
    One generation got old
    One generation got soul
    This generation got no destination to hold
    Pick up the cry

    Marty Balin and
    Paul Kantner

  5. #180
    Join Date
    Feb 2002
    Location
    Uki, NSW, Australia
    Posts
    25,770

    Default Re: More Hartley

    Quote Originally Posted by FishoutaFlorida View Post
    Good point, in fact butt joints with a backing plate is the method shown on the plans for the trailer sailor...
    I used butt blocks glued on and nailed with clenched copper nails.
    If you can afford the marine 5 ply then go with that. I assume you will be glassing the outside of the hull?
    The definition of stupid has got to be the belief that more guns will negate the bloodshed done with guns.

  6. #181
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    Default Re: More Hartley

    Quote Originally Posted by WX View Post
    I assume you will be glassing the outside of the hull?
    Yes indeed I'll be glassing the outside Gary, 1/4" seems so thin! Right now the marine 5 ply is about 3 times the cost of the 1/4" DF, so I'm hoping that the scarf joints work out.
    Oh, ain't it amazing all the people I meet?
    Got a revolution, got to revolution
    One generation got old
    One generation got soul
    This generation got no destination to hold
    Pick up the cry

    Marty Balin and
    Paul Kantner

  7. #182
    Join Date
    Feb 2002
    Location
    Uki, NSW, Australia
    Posts
    25,770

    Default Re: More Hartley

    3/8” doesn’t feel much thicker when you are out there and there’s all that water under you.
    The definition of stupid has got to be the belief that more guns will negate the bloodshed done with guns.

  8. #183
    Join Date
    Mar 2015
    Location
    Pukekohe, New Zealand
    Posts
    148

    Default Re: More Hartley

    The hull will be plenty strong enough with 1/4" (6mm) marine plywood. That is after the stringers are in place. The 16' only uses 6mm plywood.
    And you are making it stronger by glassing the outside.
    Strongly recommend using 1/4" certified marine plywood 5 ply from a reputable source. 3 ply does not have sufficient strength in the bow area where it is needed.
    The weakness of Hartley ply over stringers and frame is from the inside. Fresh water can trap along the stringers and near the transom which rots the plywood from the inside.
    5 ply marine plywood gives you 4 layers of waterproof glue as added protection.
    So after use drain the boat dry and store under cover. If any water is left inside the hull make sure it is salt water not fresh.
    I always like the skill Richard Hartley took in designing his hulls using a straight stringer in the most curved section of the hull.
    He is the only designer I have seen who universally used this technique.

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