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re: Birdwatcher II, others being built?

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  • friendlygulltoo
    I too have pondered the question of to glue or not the foam to the ply. It seems to me that gluing would provide the maximum structural benefit but, if not
    Message 1 of 7 , Jan 2, 2005
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      I too have pondered the question of to glue or not the foam to the
      ply. It seems to me that gluing would provide the maximum structural
      benefit but, if not done, the foam would still fulfill its principle
      function of keeping the two plywood skins apart.

      Other issues have been raised regarding outgassing and toxicity in
      case of fire. I would assume that the surrounding surfaces, in most
      cases, will be epoxy sealed. If we extend this to encapsulating the
      foam, we should be able to avoid most of the outgassing and
      possibilities of entrapped moisture. Even if outgassing occurs, BW and
      BWII are inherently well ventilated craft. Fire hazard may be more of
      an issue, not from the foam but from the epoxy and other coatings
      which will be the first to burn. The foam will actually be somewhat
      protected by the plywood.

      The hard hatches are another area which give me fits. I've spent may
      hours sketching alternative constructions. Problems unresolved are
      hold downs, stowage and the loss of walk through capability. I'm
      thinking of doing away with the foam and substituting a curved
      laminate which might, more easily, be stowed. I think it was Phil
      Smith who said that Bolger preferred BWI. Maybe I will accept that as
      permission to incorporate some but not all of the new design.

      Finally, I am concerned about the sheet lead with the new BWII
      configuration. I haven't done a mockup yet but it appears that there
      may be chaff along the back edge of the raised deck
    • Peter Lenihan
      I ve not the plans for BWII but Bolger does call for insulation to be used throughout Windermere in an attempt to make her a full four season
      Message 2 of 7 , Jan 2, 2005
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        I've not the plans for BWII but Bolger does call for insulation to
        be used throughout Windermere in an attempt to make her a full four
        season live-a-board.PCB&Fs call specifically for the use of the 2"
        blue Styrofoam board to be used both in the hull sides and the cabin
        roof.
        Both in conversation with "him" and several letters addressing the
        foaming stages from "them",this is what I now think I know :-)

        1)The foam MUST be thoroughly glued to the plywood panels
        2)All remaining voids found along the perimeter of a glued foam
        panel must be filled with expanding foam.
        3)Sandwich construction is very strong for its weight.

        As great luck would have it, a wonderful little sedan cruiser is
        wintering besides Windermere and is scheduled to have both her coach
        and pilot house roofs replaced due to rot. The preliminary
        inspection has revealed that the Styrofoam was originally installed
        with only globs and big lazy "S" applications of glue.This left lots
        of un-glued and un-seen gaps between the plywood shell and foam.
        Over a relatively short period of time,condensation has done its'
        evil work of rotting out several deck(roof) beams and given rise to
        soft wood along the corner posts of the coach sides.

        I was,at first, simply go to "tack" my Styrofoam in place on
        Windermere while trusting the outside shell to keep the water
        away.Thankfully,this in-the-flesh example of the effects of
        condensation appears to have been sent to me by the God of Silly
        People just in the nick of time :-) It'll be mighty tough skimping
        on the glue this Spring while from my near neighbors shelter will be
        heard the racket of gutting and repair......

        As to the question of strength with sandwich construction, Phil
        Bolger related a story to me of his own gradual conversion to this
        method of construction.A method which he confesses to having been
        leary of for years.Today,he looks back at those years with with
        amused dismay. In essence;Brad Story built a ply/foam/ply sandwich
        with door skins,suspended the finished product between two saw-
        horses and invited Phil to stand up on it to see if it would break
        or deflect much. Well....Phil did,the panel didn't and the rest is
        history. Thus we see more of this construction technique being
        applied to recent PCB design work.
        The ultimate success of this technique however,depends on being very
        thorough with all your gluing and sealing stages.Leave no "holidays"
        nor voids for moisture to come a roostin' in. It is a marvel for
        strength and light weight which hopefully will see further
        applications expressed in new designs to come.

        So...that's all I know or can contribute to this subject. I can't
        wait to hear from a few of our engineers to enlighten us with some
        raw figures or examples.


        Sincerely,

        Peter Lenihan,blissfully un-engineered and close to becoming un-
        hinged,if the New Year festivities don't stop soon, from along the
        frozen shores of the St.Lawrence...........
      • Bruce Hallman
        ... What glue did you use?
        Message 3 of 7 , Jan 2, 2005
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          > 1)The foam MUST be thoroughly glued to the plywood panels
          > Peter Lenihan

          What glue did you use?
        • Peter Lenihan
          ... Hi Bruce, Haven t begun the insulation just yet but Bolger does specify setting the Styrofoam onto a well thickened,evenly spread,layer of epoxy. A couple
          Message 4 of 7 , Jan 3, 2005
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            --- In bolger@yahoogroups.com, Bruce Hallman <bruce@h...> wrote:
            > > 1)The foam MUST be thoroughly glued to the plywood panels
            > > Peter Lenihan
            >
            > What glue did you use?

            Hi Bruce,

            Haven't begun the insulation just yet but Bolger does specify
            setting the Styrofoam onto a well thickened,evenly spread,layer of
            epoxy.
            A couple of folks around these parts,think this route too
            expensive and are suggesting I go with a proven construction grade
            adhessive specically designed for attaching foam to
            wood,steel,concrete etc...
            I'll be writing Bolger before the month is out and will seek
            clarification/opinion on the justification for epoxy along with
            viable,less costly alternative.Stay tuned... :-)

            Sincerely,

            Peter Lenihan
          • Nels
            ... Here is a link to two types of one brand of 1 rigid foam. One is hydrophobic (like me:-) and the second waterproof. They also have a sealing tape
            Message 5 of 7 , Jan 3, 2005
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              --- In bolger@yahoogroups.com, "Peter Lenihan" <peterlenihan@h...>
              wrote:
              > I'll be writing Bolger before the month is out and will seek
              > clarification/opinion on the justification for epoxy along with
              > viable,less costly alternative.Stay tuned... :-)
              >
              > Sincerely,
              >
              > Peter Lenihan

              Here is a link to two types of one brand of 1" rigid foam. One
              is "hydrophobic" (like me:-) and the second waterproof. They also
              have a sealing tape available to seal joints, but don't mention an
              adhesive.

              http://tinyurl.com/yvb7r

              There are also many sources for fire-proof paints and coatings as
              well as waterproof coatings. One example.

              http://www.hytechsales.com/fire_proofing.html

              From what I understand, in building BWII, the rigid foam is glued
              down between 1x1 longitudinals before the topsides and bottom are
              installed around the bulkheads and the outside finished off with
              exterior chines, shear strakes, taped seams and painted. (All
              exterior surfaces are epoxy coated and glassed flat on the floor,
              prior to assembly.) Then the boat is turned upright and the interior
              plywood panels are installed.

              I would expect that there has to be vertical wood supports on the
              topsides and transverse frame supports on the bottom, for the
              attachement of the bulkheads right? Because you can't attach the
              bulkheads directly to the foam. So in essence the sides and bottom
              are web frames and very rigid by themselves especially once the foam
              is cemented in.

              Therefor the interior panels could simply be installed as removable
              panels and could in fact have air circulation vents installed that
              would allow any moisture to evaporate. One could also install
              horizontal natural wood strips, as in Lestat, allowing air to
              cirulate freely behind. Any actual water would run down into the
              bilge troughs that are a part of the design and could be wiped up
              with a rag.

              This is the route that I might choose as this hull would be much
              stronger than the instant line of boats, even without the interior
              layer of plywood. After all, BW is simply a variation of the Scooner
              and HH Schooner hulls which only have one layer of 1/4" plywood!

              Cheers, Nels
            • Rick Bedard
              Yep, been my experience that no air voids can be allowed between ply and foam, or rot will find it s way. That is, unless you intentionally keep them separate
              Message 6 of 7 , Jan 3, 2005
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                Yep, been my experience that no air voids can be allowed between ply and foam, or rot will find it's way. That is, unless you intentionally keep them separate and allow for air circulation and drainage between the foam and ply. Either way, epoxy coat the ply first! I've seen white foam that tends to get pulled apart if bonded on both sides and the panel stressed. I've been told, but haven't seen it proven that the pink or blue is much better at staying intact... I'll be using pink foam held away from the plywood hull sides by fiberglass vertical spacer battens. I'll get zero added structural strength, however I'm only looking for insulation and floatation.

                Rick

                Peter Lenihan <peterlenihan@...> wrote:

                --- In bolger@yahoogroups.com, Bruce Hallman <bruce@h...> wrote:
                > > 1)The foam MUST be thoroughly glued to the plywood panels
                > > Peter Lenihan
                >
                > What glue did you use?

                Hi Bruce,

                Haven't begun the insulation just yet but Bolger does specify
                setting the Styrofoam onto a well thickened,evenly spread,layer of
                epoxy.
                A couple of folks around these parts,think this route too
                expensive and are suggesting I go with a proven construction grade
                adhessive specically designed for attaching foam to
                wood,steel,concrete etc...
                I'll be writing Bolger before the month is out and will seek
                clarification/opinion on the justification for epoxy along with
                viable,less costly alternative.Stay tuned... :-)

                Sincerely,

                Peter Lenihan





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              • oarmandt
                ... ply and foam, or rot will find it s way. That is, unless you intentionally keep them separate and allow for air circulation and drainage between the foam
                Message 7 of 7 , Jan 6, 2005
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                  --- In bolger@yahoogroups.com, Rick Bedard <sctree@y...> wrote:
                  > Yep, been my experience that no air voids can be allowed between
                  ply and foam, or rot will find it's way. That is, unless you
                  intentionally keep them separate and allow for air circulation and
                  drainage between the foam and ply. Either way, epoxy coat the ply
                  first!


                  I wonder if Dave Carnell's preservative technique (borax and boric
                  acid in ethylene glycol - see MAIB 8/15/2004 p26) wouldn't work well
                  in the foam/ply sandwich construction. I am thinking of treating
                  the interior surfaces of all the wood, letting the treatment dry,
                  then gluing all together. Epoxy seal the outside. It seems that
                  there is little chance of the treatment being washed away if the
                  outside surfaces are reasonably sealed. Any water drawn in as vapor
                  is likely to leave the same way, leaving the glycol and/or borates
                  behind.

                  I have a Birdwatcher under construction. Mine will be mostly BW 1,
                  with a few details borrowed from BW 2 where they suit me. I was
                  planning on the foam sandwich hull side panels until I saw the
                  reports of rot here. With the preservative treatment, I think it
                  stands a good chance.

                  Doug
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