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Thread: More Hartley

  1. #176
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    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
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  2. #177
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    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
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  4. #179
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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
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    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
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    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
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    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.

  9. #184
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    Default Re: More Hartley

    Just a thought on your use of flour for thickening.
    With woodflour, the wood dust can soak up the epoxy and starve the join, not leave enough to adhere to both sides. I'd have thought wheat flour would do the same. Micro balloons don't do this.
    I use woodflour, but i always apply unthickened epoxy to both mating surfaces, and then add the thickened material. Just to make sure there is enough epoxy to soak into the material. I suspect that may be why your scarf snapped.

    I think when you are coating your epoxy you may be applying a lot more than necessary. Not a problem, just expensive. How are you applying it?
    I use 100mm foam paint rollers for large areas like your CB case, and work it in well. Just enough to soak in after 2 layers, especially when adding glass, you want the glass to be tight to the ply.
    Otherwise i buy bunches of cheap glue brushes on ebay for small stuff.
    Last edited by gypsie; 07-17-2018 at 12:31 AM.
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  10. #185
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    Default Re: More Hartley

    Greetings all,

    Quote Originally Posted by WX View Post
    3/8” doesn’t feel much thicker when you are out there and there’s all that water under you.
    True that Gary, but I still love the band Blind Faith...

    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.
    Great point about the bow situation Don. While not done with the testing program yet, I keep thinking about a gray windy day and wondering...are 3 plys enough?

    Just a thought on your use of flour for thickening.
    With woodflour, the wood dust can soak up the epoxy and starve the join, not leave enough to adhere to both sides. I'd have thought wheat flour would do the same. Micro balloons don't do this.
    I use woodflour, but i always apply unthickened epoxy to both mating surfaces, and then add the thickened material. Just to make sure there is enough epoxy to soak into the material. I suspect that may be why your scarf snapped.

    I think when you are coating your epoxy you may be applying a lot more than necessary. Not a problem, just expensive. How are you applying it?
    I use 100mm foam paint rollers for large areas like your CB case, and work it in well. Just enough to soak in after 2 layers, especially when adding glass, you want the glass to be tight to the ply.
    Otherwise i buy bunches of cheap glue brushes on ebay for small stuff.
    Thanks Trev!

    Thanks for the awesome review, here we go.

    With regard to the wheat flour, I read an opinion of how this was an acceptable substitution and decided to follow that ideology. Made a lot of scarf joints with the material and stockpiled the results. While I hate to admit it, in the past couple of days, several scarf joints have failed after being installed several months ago. Now, I used a 7:1 ratio on those joints which in hindsight is too steep, but the failure was in the epoxy and it appeared that there was a significant amount of entrapped air in the glue. Which may correspond to observing air bubbles when I add the wheat flour. From your comments and some research it looks like I need to go back to the library on this item.

    Too much epoxy? I've run out of measuring containers and have noticed that my production runs now seem to have been a bit oversized. The epoxy that I'm using is about 3 years old so I'm also not too tight on this issue. All of these excuses are just that, excuses for not getting it right

    Regarding the goal of keeping the glass to be tight to the ply, I'm with you on that, has to happen.

    With wood surfboards I always use an un-thickened epoxy on the wood before a light sand, lay glass and spread the epoxy. The lack of the sealer coat in a joint situation could certainly be my problem.

    No rollers for me yet, I'm using cheap glue brushes from the internet. May change that when I start to scarf larger pieces.

    For more info on ply & joint selection check out this sidebar:

    http://forum.woodenboat.com/showthre...trailer-sailer

    Thanks all for your observations and input, will definitely benefit this task!

    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

  11. #186
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    Default Re: More Hartley

    Having just bought a sheet of quality (OZ made) marine grade ply I strongly recommend you save your pennies and get quality.
    The definition of stupid has got to be the belief that more guns will negate the bloodshed done with guns.

  12. #187
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    Default Re: More Hartley

    Greetings all,

    Quote Originally Posted by WX View Post
    Having just bought a sheet of quality (OZ made) marine grade ply I strongly recommend you save your pennies and get quality.
    I'm beginning to come to that conclusion. Haven't even finished testing the DF sample but I've got a huge case of the willies about sticking with that material. Thanks for the opinion Gary, it's greatly appreciated.
    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

  13. #188
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    Default Re: More Hartley

    The International Cadet dinghy I am restoring has 'but blocks' or covering strips on a 4 piece deck. I was going to scarf 2 bigger sheets and give her a one piece deck with darts, but seeing it's a restoration should I stick to the original build standard? The other way I thought of was to rebate the frames under the joints enough to take a ply 'but block' and so leave a smooth deck. Any thoughts?

  14. #189
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    Default Re: More Hartley

    Greetings all,

    Quote Originally Posted by WX View Post
    Having just bought a sheet of quality (OZ made) marine grade ply I strongly recommend you save your pennies and get quality.
    Well Gary, after a whole lot of testing that didn't prove much, I've come to the conclusion that your are right. 6mm, 5 ply BS1088 for the hull, and seriously considering butt backer joint instead of scarf. Maybe do some more testing, but...

    Anyway, on with the stringers, first I did something that I didn't do on the chines or other stringers.

    DSCF7279.jpg

    which helps the stringers get to the right spot.

    DSCF7280.jpg

    Finally starting to take shape, I'm seeing how I will need to shape the chines now too. So I'm pumped!

    DSCF7289.jpg

    Thanks again for all of your comments and observations!

    Now it is on to the bow stringers, buying plywood and some planking. Yahoo!

    On the medium range radar is a trailer and centerboard. I've think I've got the centerboard figured out, but would love trailer ideas. Size, material type, place to find one, etc.

    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

  15. #190
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    Default Re: More Hartley

    She's looking good mate.
    The definition of stupid has got to be the belief that more guns will negate the bloodshed done with guns.

  16. #191
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    Default Re: More Hartley

    You won't need much of a trailer for such a light weight boat, but, look for a trailer which keeps the load as low down as possible, single axle for manoeuvrability, long draw bar so as to get the boat out deep enough before the tow vehicle reaches the drink, and you might want some of those guide post thingamajiggys (let's just call them majiggys) because a breeze or current will make the boat drift annoyingly side on to the trailer when trying to load back on. The less joins and complexity in the construction the better in terms of reducing corrosion issues down the track.

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