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Plywood checking on Brucesboat

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  • porneaux
    In it s third season of use I noticed for the first time some minor checking on my Brucesboat floor panel. It s been stored upright on the trailer with the
    Message 1 of 15 , Jun 21, 2013
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      In it's third season of use I noticed for the first time some minor checking on my Brucesboat floor panel. It's been stored upright on the trailer with the transom plug pulled. Some leaves did accumulate and probably held moisture on the floor panels, but with epoxy encapsulation I thought I'd be OK.

      I used 5-ply 1/2 inch Auroco exterior plywood fully encapsulated in epoxy (but not glassed on the interior) with exposed expoxy coated with a quality porch latex paint.

      The checking on painted epoxied areas has texture - I can feel the checking on the surface. Inside the motor box I coated with expoxy but didn't paint - no exposure to the sun, I can see the checking through the epoxy coat but I can't feel it on the surface.

      I'm in the middle of an AF4 build now halted dead in its tracks until I get this sorted.

      I know many builders get better life from their plywood without the expoxy encapsulation. My boat is more expensive, heavier and less durable!

      I have 2 primary questions:

      1) What did I do wrong? Clearly epoxy encapsulation is not a cure-all for non-marine grade plywoood to be stored exposed to the elements.

      2) Can I repair this by sanding into the checked ply(s) and re-epoxying with glass?


      Brian Nimmo
    • joe_mapango
      There are vastly more knowledgeable persons on the list (but that never stopped me!) As far as I know, epoxy encapsulation only has never been claimed to stop
      Message 2 of 15 , Jun 21, 2013
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        There are vastly more knowledgeable persons on the list (but that never stopped me!)

        As far as I know, epoxy encapsulation only has never been claimed to stop checking especially on fur/larch ply. Additionally, Epoxy exposed to UV will degrade and self check within months, or even weeks.

        I really don't think you did anything wrong. I think you just had expectations of epoxy encapsulation that were not lined up with reality. Even on fancy marine ply, you can get checking without glass/epoxy.

        I hope this helps. Don't stop your build. The fact that you were able to even finish your bruceboat makes you a star homebuilder in my book!


        Chris Curtis
        S/V Romany
        curtisfamilyadventures.wordpress.com

        --- In Michalak@yahoogroups.com, owwin@... wrote:
        >
        >
        > In it's third season of use I noticed for the first time some minor checking on my Brucesboat floor panel. It's been stored upright on the trailer with the transom plug pulled. Some leaves did accumulate and probably held moisture on the floor panels, but with epoxy encapsulation I thought I'd be OK.
        >
        > I used 5-ply 1/2 inch Auroco exterior plywood fully encapsulated in epoxy (but not glassed on the interior) with exposed expoxy coated with a quality porch latex paint.
        >
        > The checking on painted epoxied areas has texture - I can feel the checking on the surface. Inside the motor box I coated with expoxy but didn't paint - no exposure to the sun, I can see the checking through the epoxy coat but I can't feel it on the surface.
        >
        > I'm in the middle of an AF4 build now halted dead in its tracks until I get this sorted.
        >
        > I know many builders get better life from their plywood without the expoxy encapsulation. My boat is more expensive, heavier and less durable!
        >
        > I have 2 primary questions:
        >
        > 1) What did I do wrong? Clearly epoxy encapsulation is not a cure-all for non-marine grade plywoood to be stored exposed to the elements.
        >
        > 2) Can I repair this by sanding into the checked ply(s) and re-epoxying with glass?
        >
        >
        > Brian Nimmo
        >
      • prairiedog2332
        Not being familiar with that type of plywood I Googled Auroco plywood checking. and found the thread here that may be of interest. Particularly the 4th post
        Message 3 of 15 , Jun 21, 2013
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          Not being familiar with that type of plywood I Googled "Auroco plywood
          checking." and found the thread here that may be of interest.
          Particularly the 4th post by fracco, Seems the quality also has gone
          down a lot in the past few years just like Luan Plywood Underlayment.
          http://forums.bateau2.com/viewtopic.php?f=5&t=20531
          <http://forums.bateau2.com/viewtopic.php?f=5&t=20531>

          Nels



          --- In Michalak@yahoogroups.com, "joe_mapango" wrote:
          >
          > There are vastly more knowledgeable persons on the list (but that
          never stopped me!)
          >
          > As far as I know, epoxy encapsulation only has never been claimed to
          stop checking especially on fur/larch ply. Additionally, Epoxy exposed
          to UV will degrade and self check within months, or even weeks.
          >
          > I really don't think you did anything wrong. I think you just had
          expectations of epoxy encapsulation that were not lined up with reality.
          Even on fancy marine ply, you can get checking without glass/epoxy.
          >
          > I hope this helps. Don't stop your build. The fact that you were
          able to even finish your bruceboat makes you a star homebuilder in my
          book!
          >
          >
          > Chris Curtis
          > S/V Romany
          > curtisfamilyadventures.wordpress.com
          >
          > --- In Michalak@yahoogroups.com, owwin@ wrote:
          > >
          > >
          > > In it's third season of use I noticed for the first time some minor
          checking on my Brucesboat floor panel. It's been stored upright on the
          trailer with the transom plug pulled. Some leaves did accumulate and
          probably held moisture on the floor panels, but with epoxy encapsulation
          I thought I'd be OK.
          > >
          > > I used 5-ply 1/2 inch Auroco exterior plywood fully encapsulated in
          epoxy (but not glassed on the interior) with exposed expoxy coated with
          a quality porch latex paint.
          > >
          > > The checking on painted epoxied areas has texture - I can feel the
          checking on the surface. Inside the motor box I coated with expoxy but
          didn't paint - no exposure to the sun, I can see the checking through
          the epoxy coat but I can't feel it on the surface.
          > >
          > > I'm in the middle of an AF4 build now halted dead in its tracks
          until I get this sorted.
          > >
          > > I know many builders get better life from their plywood without the
          expoxy encapsulation. My boat is more expensive, heavier and less
          durable!
          > >
          > > I have 2 primary questions:
          > >
          > > 1) What did I do wrong? Clearly epoxy encapsulation is not a
          cure-all for non-marine grade plywoood to be stored exposed to the
          elements.
          > >
          > > 2) Can I repair this by sanding into the checked ply(s) and
          re-epoxying with glass?
          > >
          > >
          > > Brian Nimmo
          > >
          >



          [Non-text portions of this message have been removed]
        • Joe T
          Your boat has no protection from the sun (heat, UV) or moisture. Suggest you build a cover structure to keep it cool and dry. Ample ventilation is also
          Message 4 of 15 , Jun 22, 2013
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            Your boat has no protection from the sun (heat, UV) or moisture. Suggest you build a cover structure to keep it cool and dry. Ample ventilation is also important. My epoxied and painted Oldshoe was so protected while stored outdoors and showed no checking after many years.

            Joe T

            --- In Michalak@yahoogroups.com, owwin@... wrote:
            >
            >
            > In it's third season of use I noticed for the first time some minor checking on my Brucesboat floor panel. It's been stored upright on the trailer with the transom plug pulled. Some leaves did accumulate and probably held moisture on the floor panels, but with epoxy encapsulation I thought I'd be OK.
            >
            > I used 5-ply 1/2 inch Auroco exterior plywood fully encapsulated in epoxy (but not glassed on the interior) with exposed expoxy coated with a quality porch latex paint.
            >
            > The checking on painted epoxied areas has texture - I can feel the checking on the surface. Inside the motor box I coated with expoxy but didn't paint - no exposure to the sun, I can see the checking through the epoxy coat but I can't feel it on the surface.
            >
            > I'm in the middle of an AF4 build now halted dead in its tracks until I get this sorted.
            >
            > I know many builders get better life from their plywood without the expoxy encapsulation. My boat is more expensive, heavier and less durable!
            >
            > I have 2 primary questions:
            >
            > 1) What did I do wrong? Clearly epoxy encapsulation is not a cure-all for non-marine grade plywoood to be stored exposed to the elements.
            >
            > 2) Can I repair this by sanding into the checked ply(s) and re-epoxying with glass?
            >
            >
            > Brian Nimmo
            >
          • souderscott997
            I would agree with you on all but the heat part. I built my Wooboto in my garage here in Aurora, CO. Day temps in the summer are well over 100 in the garage.
            Message 5 of 15 , Jun 22, 2013
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              I would agree with you on all but the heat part. I built my Wooboto in my garage here in Aurora, CO. Day temps in the summer are well over 100 in the garage. Heat I don't think effected anything other that I had to use slow hardener and still needed to have the game plan down as soon as it was mixed. I had pots start heating up on me within 12 minutes a few times. Anyways the boat turned out great as a matter of fact the wife and I are heading to the lake in about an hour or so. Heat...not a concern...everything else you mentioned does need protection especially direct UV exposure.
              --- In Michalak@yahoogroups.com, "Joe T" <scsbmsjoe@...> wrote:
              >
              > Your boat has no protection from the sun (heat, UV) or moisture. Suggest you build a cover structure to keep it cool and dry. Ample ventilation is also important. My epoxied and painted Oldshoe was so protected while stored outdoors and showed no checking after many years.
              >
              > Joe T
              >
              > --- In Michalak@yahoogroups.com, owwin@ wrote:
              > >
              > >
              > > In it's third season of use I noticed for the first time some minor checking on my Brucesboat floor panel. It's been stored upright on the trailer with the transom plug pulled. Some leaves did accumulate and probably held moisture on the floor panels, but with epoxy encapsulation I thought I'd be OK.
              > >
              > > I used 5-ply 1/2 inch Auroco exterior plywood fully encapsulated in epoxy (but not glassed on the interior) with exposed expoxy coated with a quality porch latex paint.
              > >
              > > The checking on painted epoxied areas has texture - I can feel the checking on the surface. Inside the motor box I coated with expoxy but didn't paint - no exposure to the sun, I can see the checking through the epoxy coat but I can't feel it on the surface.
              > >
              > > I'm in the middle of an AF4 build now halted dead in its tracks until I get this sorted.
              > >
              > > I know many builders get better life from their plywood without the expoxy encapsulation. My boat is more expensive, heavier and less durable!
              > >
              > > I have 2 primary questions:
              > >
              > > 1) What did I do wrong? Clearly epoxy encapsulation is not a cure-all for non-marine grade plywoood to be stored exposed to the elements.
              > >
              > > 2) Can I repair this by sanding into the checked ply(s) and re-epoxying with glass?
              > >
              > >
              > > Brian Nimmo
              > >
              >
            • prairiedog2332
              The air temperature in the shade (garage) is not the same as what the surface temperature of something might be getting up to in bright direct summer sun.
              Message 6 of 15 , Jun 22, 2013
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                The air temperature in the shade (garage) is not the same as what the
                surface temperature of something might be getting up to in bright direct
                summer sun. Depends on how dark the surface is of course, but it can get
                up to twice as high as the air temperature in the shade and can soften
                or even wipe out epoxy as Chris mentions. Plus the UV affect and the
                temperature fluctuation over night if you live at higher altitude or in
                a semi-arid climate. And the wetting and drying cycle when it rains can
                all add up to significant accelerated weathering of plywood. And pine is
                the most affected as it has alternating soft and hard rings.

                A good cover is really worthwhile for a wooden boat and not just the
                open designs. And a good cover takes some effort and money to construct
                and fit. Blue polytarp secured with a few bungie cords just won't do it.
                I badly damaged 2 boats that way.

                Nels


                --- In Michalak@yahoogroups.com, "souderscott997" wrote:
                >
                >
                > I would agree with you on all but the heat part. I built my Wooboto in
                my garage here in Aurora, CO. Day temps in the summer are well over 100
                in the garage. Heat I don't think effected anything other that I had to
                use slow hardener and still needed to have the game plan down as soon as
                it was mixed. I had pots start heating up on me within 12 minutes a few
                times. Anyways the boat turned out great as a matter of fact the wife
                and I are heading to the lake in about an hour or so. Heat...not a
                concern...everything else you mentioned does need protection especially
                direct UV exposure.




                [Non-text portions of this message have been removed]
              • Martin Houston
                I have found that any plywood left outside that is not glassed with cloth will check no matter what you coat it with. From: prairiedog2332
                Message 7 of 15 , Jun 22, 2013
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                  I have found that any plywood left outside that is not glassed with cloth will check no matter what you coat it with.

                  From: prairiedog2332 <nelsarv@...>
                  To: Michalak@yahoogroups.com
                  Sent: Friday, June 21, 2013 6:59 PM
                  Subject: [Michalak] Re: Plywood checking on Brucesboat

                   
                  Not being familiar with that type of plywood I Googled "Auroco plywood
                  checking." and found the thread here that may be of interest.
                  Particularly the 4th post by fracco, Seems the quality also has gone
                  down a lot in the past few years just like Luan Plywood Underlayment.
                  http://forums.bateau2.com/viewtopic.php?f=5&t=20531
                  <http://forums.bateau2.com/viewtopic.php?f=5&t=20531>

                  Nels

                  --- In mailto:Michalak%40yahoogroups.com, "joe_mapango" wrote:
                  >
                  > There are vastly more knowledgeable persons on the list (but that
                  never stopped me!)
                  >
                  > As far as I know, epoxy encapsulation only has never been claimed to
                  stop checking especially on fur/larch ply. Additionally, Epoxy exposed
                  to UV will degrade and self check within months, or even weeks.
                  >
                  > I really don't think you did anything wrong. I think you just had
                  expectations of epoxy encapsulation that were not lined up with reality.
                  Even on fancy marine ply, you can get checking without glass/epoxy.
                  >
                  > I hope this helps. Don't stop your build. The fact that you were
                  able to even finish your bruceboat makes you a star homebuilder in my
                  book!
                  >
                  >
                  > Chris Curtis
                  > S/V Romany
                  > curtisfamilyadventures.wordpress.com
                  >
                  > --- In mailto:Michalak%40yahoogroups.com, owwin@ wrote:
                  > >
                  > >
                  > > In it's third season of use I noticed for the first time some minor
                  checking on my Brucesboat floor panel. It's been stored upright on the
                  trailer with the transom plug pulled. Some leaves did accumulate and
                  probably held moisture on the floor panels, but with epoxy encapsulation
                  I thought I'd be OK.
                  > >
                  > > I used 5-ply 1/2 inch Auroco exterior plywood fully encapsulated in
                  epoxy (but not glassed on the interior) with exposed expoxy coated with
                  a quality porch latex paint.
                  > >
                  > > The checking on painted epoxied areas has texture - I can feel the
                  checking on the surface. Inside the motor box I coated with expoxy but
                  didn't paint - no exposure to the sun, I can see the checking through
                  the epoxy coat but I can't feel it on the surface.
                  > >
                  > > I'm in the middle of an AF4 build now halted dead in its tracks
                  until I get this sorted.
                  > >
                  > > I know many builders get better life from their plywood without the
                  expoxy encapsulation. My boat is more expensive, heavier and less
                  durable!
                  > >
                  > > I have 2 primary questions:
                  > >
                  > > 1) What did I do wrong? Clearly epoxy encapsulation is not a
                  cure-all for non-marine grade plywoood to be stored exposed to the
                  elements.
                  > >
                  > > 2) Can I repair this by sanding into the checked ply(s) and
                  re-epoxying with glass?
                  > >
                  > >
                  > > Brian Nimmo
                  > >
                  >

                  [Non-text portions of this message have been removed]




                  [Non-text portions of this message have been removed]
                • Martin Houston
                  Would say yes, sand it good & glass with epoxy resin & cloth. From: joe_mapango To: Michalak@yahoogroups.com Sent:
                  Message 8 of 15 , Jun 22, 2013
                  • 0 Attachment
                    Would say yes, sand it good & glass with epoxy resin & cloth.


                    From: joe_mapango <ccurtis-keyword-sailing.6d3753@...>
                    To: Michalak@yahoogroups.com
                    Sent: Friday, June 21, 2013 3:51 PM
                    Subject: [Michalak] Re: Plywood checking on Brucesboat

                     
                    There are vastly more knowledgeable persons on the list (but that never stopped me!)

                    As far as I know, epoxy encapsulation only has never been claimed to stop checking especially on fur/larch ply. Additionally, Epoxy exposed to UV will degrade and self check within months, or even weeks.

                    I really don't think you did anything wrong. I think you just had expectations of epoxy encapsulation that were not lined up with reality. Even on fancy marine ply, you can get checking without glass/epoxy.

                    I hope this helps. Don't stop your build. The fact that you were able to even finish your bruceboat makes you a star homebuilder in my book!

                    Chris Curtis
                    S/V Romany
                    curtisfamilyadventures.wordpress.com

                    --- In mailto:Michalak%40yahoogroups.com, owwin@... wrote:
                    >
                    >
                    > In it's third season of use I noticed for the first time some minor checking on my Brucesboat floor panel. It's been stored upright on the trailer with the transom plug pulled. Some leaves did accumulate and probably held moisture on the floor panels, but with epoxy encapsulation I thought I'd be OK.
                    >
                    > I used 5-ply 1/2 inch Auroco exterior plywood fully encapsulated in epoxy (but not glassed on the interior) with exposed expoxy coated with a quality porch latex paint.
                    >
                    > The checking on painted epoxied areas has texture - I can feel the checking on the surface. Inside the motor box I coated with expoxy but didn't paint - no exposure to the sun, I can see the checking through the epoxy coat but I can't feel it on the surface.
                    >
                    > I'm in the middle of an AF4 build now halted dead in its tracks until I get this sorted.
                    >
                    > I know many builders get better life from their plywood without the expoxy encapsulation. My boat is more expensive, heavier and less durable!
                    >
                    > I have 2 primary questions:
                    >
                    > 1) What did I do wrong? Clearly epoxy encapsulation is not a cure-all for non-marine grade plywoood to be stored exposed to the elements.
                    >
                    > 2) Can I repair this by sanding into the checked ply(s) and re-epoxying with glass?
                    >
                    >
                    > Brian Nimmo
                    >




                    [Non-text portions of this message have been removed]
                  • prairiedog2332
                    I would have to agree, but that would incur one heck of a lot work, especially if you looking at another build! One fellow I know of who actually lives in CO
                    Message 9 of 15 , Jun 22, 2013
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                      I would have to agree, but that would incur one heck of a lot work,
                      especially if you looking at another build!

                      One fellow I know of who actually lives in CO is John Kolb who finished
                      the interior of an open hull with truck box liner. Might be worth trying
                      to contact him for his thoughts?

                      http://www.kolbsadventures.com/boatbuilding_index.htm
                      <http://www.kolbsadventures.com/boatbuilding_index.htm>

                      http://www.durabakcompany.com/marine.htm
                      <http://www.durabakcompany.com/marine.htm>

                      Another fellow finished the exterior of his fir plywood motorboat hull
                      with a brand of exterior acrylic water based house paint to which he
                      added milled glass and silica as a filler. Last I heard it had not
                      checked after a couple years of usage. But I have to search my files for
                      the paint brand and type he claims works best. I think a high-build
                      undercoat actually, then a finish coat of choice over. Plan on trying
                      that myself as all you just have to do is rough up the existing paint if
                      it is already acrylic. I think you folks down south refer to it as
                      "latex" paint, even though it has no latex in it?

                      http://www.duckworksbbs.com/supplies/additives/milled/index.htm
                      <http://www.duckworksbbs.com/supplies/additives/milled/index.htm>

                      Nels




                      --- In Michalak@yahoogroups.com, Martin Houston wrote:
                      >
                      > Would say yes, sand it good & glass with epoxy resin & cloth.
                      >




                      [Non-text portions of this message have been removed]
                    • porneaux
                      Thanks everyone for the information and advice on plywood checking. Just got back from an overnighter on the Missouri river with the Brucesboat and a buddy.
                      Message 10 of 15 , Jun 24, 2013
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                        Thanks everyone for the information and advice on plywood checking.

                        Just got back from an overnighter on the Missouri river with the Brucesboat and a buddy. 25 mph winds blowing against the currrent made for some nasty breakers in the sections parallel to the wind. Buried the bow into "brown" water several times and finally retreated to a lee shore and set camp.

                        In the really rough stuff I was well beyond my comfort zone and probably near the boat's limit, but have to say it performed admirably. She stayed pointed where I steered, the pointy bow didn't pound, and the boat didn't flex. No big water crashing over the bow when burried into the back of a crest.

                        Looks like my first boatbuiliding project should have been "Build a place to store the finished boat(s). Because that isn't feasible in the short term, and because I love my Brucesboat, I'm going to sand the checks down and epoxy/glass-tape the area. Will be my early season ritual. Will eventually have a glassed interior!

                        Thanks again for the information.

                        Brian Nimmo



                        --- In Michalak@yahoogroups.com, "prairiedog2332" <nelsarv@...> wrote:
                        >
                        > I would have to agree, but that would incur one heck of a lot work,
                        > especially if you looking at another build!
                        >
                        > One fellow I know of who actually lives in CO is John Kolb who finished
                        > the interior of an open hull with truck box liner. Might be worth trying
                        > to contact him for his thoughts?
                        >
                        > http://www.kolbsadventures.com/boatbuilding_index.htm
                        > <http://www.kolbsadventures.com/boatbuilding_index.htm>
                        >
                        > http://www.durabakcompany.com/marine.htm
                        > <http://www.durabakcompany.com/marine.htm>
                        >
                        > Another fellow finished the exterior of his fir plywood motorboat hull
                        > with a brand of exterior acrylic water based house paint to which he
                        > added milled glass and silica as a filler. Last I heard it had not
                        > checked after a couple years of usage. But I have to search my files for
                        > the paint brand and type he claims works best. I think a high-build
                        > undercoat actually, then a finish coat of choice over. Plan on trying
                        > that myself as all you just have to do is rough up the existing paint if
                        > it is already acrylic. I think you folks down south refer to it as
                        > "latex" paint, even though it has no latex in it?
                        >
                        > http://www.duckworksbbs.com/supplies/additives/milled/index.htm
                        > <http://www.duckworksbbs.com/supplies/additives/milled/index.htm>
                        >
                        > Nels
                        >
                        >
                        >
                        >
                        > --- In Michalak@yahoogroups.com, Martin Houston wrote:
                        > >
                        > > Would say yes, sand it good & glass with epoxy resin & cloth.
                        > >
                        >
                        >
                        >
                        >
                        > [Non-text portions of this message have been removed]
                        >
                      • Crandall, Chris S.
                        In short, epoxy painted over plywood does NOT stop checking, although it slows it down some. To prevent checking, there are two choices: 1) Use a plywood that
                        Message 11 of 15 , Jun 24, 2013
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                          In short, epoxy painted over plywood does NOT stop checking, although it slows it down some. To prevent checking, there are two choices:

                          1) Use a plywood that is not prone to checking. This is the pricy stuff, made overseas, and usually involves cutting down some of the rainforest.

                          2) Use fiberglass cloth with that epoxy.

                          Checking comes from moisture cycling. The earlywood and latewood in douglas fir (in particular) expand and contract and notably different rates. This, in plywood veneers, leads to tearing of the fibers (checking) with repeated cycling. Plywood kept at constant moisture doesn't check--but what boat doesn't moisture cycle? (Boats kept in museums, perhaps.) Since tropical rainforests have more constant climate/seasons, there is not the pronounced earlywood/latewood structure--that's the rings you see in the wood [try counting rings in teak or iroko]--and so the checking is less of a problem.

                          So the painting on of epoxy slows down, but as you've learned, does not prevent checking. Since you're not going to replace the plywood on your boat, you have a few options:

                          1) Sand, sand, sand to bare wood, apply a lightweight fiberglass cloth (4 oz is fine, 2oz might be OK), set in epoxy.

                          2) Sand some, and patch. This is the easiest, and it isn't bad. Sand it down as much as you can stand, and then patch with epoxy and filler. I have come to like WEST System Microlight filler. It sands very, very easily. I will never go back to phenolic microballoons. (It's also a pleasing color, which the maroon balloons were not.)

                          3) Paint another coat over it, and recognize that checking is only a problem for you if they trap moisture. If you can keep the boat dry, your problems are primarily cosmetic.

                          And remember to enjoy your boat as it is, and to plan another build.

                          -Chris
                        • Joseph Stromski
                          I agree with everything below, except the pricy stuff comment. My AF4 used 1/2 MDO for the bottom, and 1/4 baltic birch premium underlayment for the side
                          Message 12 of 15 , Jun 24, 2013
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                            I agree with everything below, except the "pricy stuff" comment. My AF4 used 1/2" MDO for the bottom, and 1/4" baltic birch premium underlayment for the side panels. Both obtained cheaply from my local big box store (Menards). The MDO hasn't/won't check due the the facing on it, and the birch shows no indication of checking with only an epoxy spit coat, no glass, after nearly 4 years. 

                            Best,
                            Joe


                            ________________________________
                            From: "Crandall, Chris S." <crandall@...>
                            To: "Michalak@yahoogroups.com" <Michalak@yahoogroups.com>
                            Sent: Monday, June 24, 2013 9:49 AM
                            Subject: [Michalak] Re: Plywood checking on Brucesboat



                             
                            In short, epoxy painted over plywood does NOT stop checking, although it slows it down some. To prevent checking, there are two choices:

                            1) Use a plywood that is not prone to checking. This is the pricy stuff, made overseas, and usually involves cutting down some of the rainforest.

                            2) Use fiberglass cloth with that epoxy.

                            Checking comes from moisture cycling. The earlywood and latewood in douglas fir (in particular) expand and contract and notably different rates. This, in plywood veneers, leads to tearing of the fibers (checking) with repeated cycling. Plywood kept at constant moisture doesn't check--but what boat doesn't moisture cycle? (Boats kept in museums, perhaps.) Since tropical rainforests have more constant climate/seasons, there is not the pronounced earlywood/latewood structure--that's the rings you see in the wood [try counting rings in teak or iroko]--and so the checking is less of a problem.

                            So the painting on of epoxy slows down, but as you've learned, does not prevent checking. Since you're not going to replace the plywood on your boat, you have a few options:

                            1) Sand, sand, sand to bare wood, apply a lightweight fiberglass cloth (4 oz is fine, 2oz might be OK), set in epoxy.

                            2) Sand some, and patch. This is the easiest, and it isn't bad. Sand it down as much as you can stand, and then patch with epoxy and filler. I have come to like WEST System Microlight filler. It sands very, very easily. I will never go back to phenolic microballoons. (It's also a pleasing color, which the maroon balloons were not.)

                            3) Paint another coat over it, and recognize that checking is only a problem for you if they trap moisture. If you can keep the boat dry, your problems are primarily cosmetic.

                            And remember to enjoy your boat as it is, and to plan another build.

                            -Chris




                            [Non-text portions of this message have been removed]
                          • Brian Nimmo
                            Hi Joe, Does the MDO have the nice facing on both sides? Does the facing adhere to epoxy like normal plywood? How do you store your AF4 during long periods
                            Message 13 of 15 , Jun 24, 2013
                            • 0 Attachment
                              Hi Joe,

                              Does the MDO have the nice facing on both sides? Does the facing adhere to epoxy like normal plywood? How do you store your AF4 during long periods of non-use?

                              Thanks.

                              Brian


                              To: Michalak@yahoogroups.com
                              From: j.stromski@...
                              Date: Mon, 24 Jun 2013 09:12:56 -0700
                              Subject: Re: [Michalak] Re: Plywood checking on Brucesboat


























                              I agree with everything below, except the "pricy stuff" comment. My AF4 used 1/2" MDO for the bottom, and 1/4" baltic birch premium underlayment for the side panels. Both obtained cheaply from my local big box store (Menards). The MDO hasn't/won't check due the the facing on it, and the birch shows no indication of checking with only an epoxy spit coat, no glass, after nearly 4 years.



                              Best,

                              Joe



                              ________________________________

                              From: "Crandall, Chris S." <crandall@...>

                              To: "Michalak@yahoogroups.com" <Michalak@yahoogroups.com>

                              Sent: Monday, June 24, 2013 9:49 AM

                              Subject: [Michalak] Re: Plywood checking on Brucesboat







                              In short, epoxy painted over plywood does NOT stop checking, although it slows it down some. To prevent checking, there are two choices:



                              1) Use a plywood that is not prone to checking. This is the pricy stuff, made overseas, and usually involves cutting down some of the rainforest.



                              2) Use fiberglass cloth with that epoxy.



                              Checking comes from moisture cycling. The earlywood and latewood in douglas fir (in particular) expand and contract and notably different rates. This, in plywood veneers, leads to tearing of the fibers (checking) with repeated cycling. Plywood kept at constant moisture doesn't check--but what boat doesn't moisture cycle? (Boats kept in museums, perhaps.) Since tropical rainforests have more constant climate/seasons, there is not the pronounced earlywood/latewood structure--that's the rings you see in the wood [try counting rings in teak or iroko]--and so the checking is less of a problem.



                              So the painting on of epoxy slows down, but as you've learned, does not prevent checking. Since you're not going to replace the plywood on your boat, you have a few options:



                              1) Sand, sand, sand to bare wood, apply a lightweight fiberglass cloth (4 oz is fine, 2oz might be OK), set in epoxy.



                              2) Sand some, and patch. This is the easiest, and it isn't bad. Sand it down as much as you can stand, and then patch with epoxy and filler. I have come to like WEST System Microlight filler. It sands very, very easily. I will never go back to phenolic microballoons. (It's also a pleasing color, which the maroon balloons were not.)



                              3) Paint another coat over it, and recognize that checking is only a problem for you if they trap moisture. If you can keep the boat dry, your problems are primarily cosmetic.



                              And remember to enjoy your boat as it is, and to plan another build.



                              -Chris



                              [Non-text portions of this message have been removed]



















                              [Non-text portions of this message have been removed]
                            • porneaux
                              Great information Chris, thank you. I just returned from a trip enjoying my Bboat just as it is (checking and all), and am 30 hours into the next build - an
                              Message 14 of 15 , Jun 24, 2013
                              • 0 Attachment
                                Great information Chris, thank you.

                                I just returned from a trip enjoying my Bboat just as it is (checking and all), and am 30 hours into the next build - an AF4.

                                --- In Michalak@yahoogroups.com, "Crandall, Chris S." <crandall@...> wrote:
                                >
                                > And remember to enjoy your boat as it is, and to plan another build.
                                >
                                > -Chris
                                >
                              • Joseph Stromski
                                The MDO I used had non-primed facing on 2 sides. There s quite a few different varieties of it out there, however. Primed, non-primed, etc.  I handled it no
                                Message 15 of 15 , Jun 24, 2013
                                • 0 Attachment
                                  The MDO I used had non-primed facing on 2 sides. There's quite a few different varieties of it out there, however. Primed, non-primed, etc.  I handled it no differently than regular plywood. The boat is garaged. 

                                  Best,
                                  Joe


                                  ________________________________
                                  From: Brian Nimmo <owwin@...>
                                  To: "Michalak@yahoogroups.com" <michalak@yahoogroups.com>
                                  Sent: Monday, June 24, 2013 11:23 AM
                                  Subject: RE: [Michalak] Re: Plywood checking on Brucesboat


                                  Hi Joe,

                                  Does the MDO have the nice facing on both sides?  Does the facing adhere to epoxy like normal plywood?  How do you store your AF4 during long periods of non-use?

                                  Thanks.

                                  Brian


                                  To: Michalak@yahoogroups.com
                                  From: j.stromski@...
                                  Date: Mon, 24 Jun 2013 09:12:56 -0700
                                  Subject: Re: [Michalak] Re: Plywood checking on Brucesboat




















                                   


                                     
                                       
                                       
                                        I agree with everything below, except the "pricy stuff" comment. My AF4 used 1/2" MDO for the bottom, and 1/4" baltic birch premium underlayment for the side panels. Both obtained cheaply from my local big box store (Menards). The MDO hasn't/won't check due the the facing on it, and the birch shows no indication of checking with only an epoxy spit coat, no glass, after nearly 4 years.



                                  Best,

                                  Joe



                                  ________________________________

                                  From: "Crandall, Chris S." <crandall@...>

                                  To: "Michalak@yahoogroups.com" <Michalak@yahoogroups.com>

                                  Sent: Monday, June 24, 2013 9:49 AM

                                  Subject: [Michalak] Re: Plywood checking on Brucesboat





                                   

                                  In short, epoxy painted over plywood does NOT stop checking, although it slows it down some. To prevent checking, there are two choices:



                                  1) Use a plywood that is not prone to checking. This is the pricy stuff, made overseas, and usually involves cutting down some of the rainforest.



                                  2) Use fiberglass cloth with that epoxy.



                                  Checking comes from moisture cycling. The earlywood and latewood in douglas fir (in particular) expand and contract and notably different rates. This, in plywood veneers, leads to tearing of the fibers (checking) with repeated cycling. Plywood kept at constant moisture doesn't check--but what boat doesn't moisture cycle? (Boats kept in museums, perhaps.) Since tropical rainforests have more constant climate/seasons, there is not the pronounced earlywood/latewood structure--that's the rings you see in the wood [try counting rings in teak or iroko]--and so the checking is less of a problem.



                                  So the painting on of epoxy slows down, but as you've learned, does not prevent checking. Since you're not going to replace the plywood on your boat, you have a few options:



                                  1) Sand, sand, sand to bare wood, apply a lightweight fiberglass cloth (4 oz is fine, 2oz might be OK), set in epoxy.



                                  2) Sand some, and patch. This is the easiest, and it isn't bad. Sand it down as much as you can stand, and then patch with epoxy and filler. I have come to like WEST System Microlight filler. It sands very, very easily. I will never go back to phenolic microballoons. (It's also a pleasing color, which the maroon balloons were not.)



                                  3) Paint another coat over it, and recognize that checking is only a problem for you if they trap moisture. If you can keep the boat dry, your problems are primarily cosmetic.



                                  And remember to enjoy your boat as it is, and to plan another build.



                                  -Chris



                                  [Non-text portions of this message have been removed]






                                     
                                     

                                     
                                     






                                                           

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