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letting buoyancy chambers breath?

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  • Curran Bishop
    I was talking to a guy who was admiring the AF4 and he said he had built fiberglass johnboats and warned me to make sure the buoyancy chambers had a means of
    Message 1 of 8 , Jul 22 9:30 PM
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      I was talking to a guy who was admiring the AF4 and he said he had built
      fiberglass johnboats and warned me to make sure the buoyancy chambers had a
      means of breathing. He pointed out that with the way I have mine set up
      with pop-out deck-plates to keep them water-tight the sun hitting the sides
      of them can heat the air inside and make it expand, compromising the seams
      of the chambers. While I store and transport the boat with the deck-plates
      open, there is still opportunity for heating when the boat's in use - how
      serious a concern is this?

      I've been thinking something along the lines of a 1/8" hole on the boat's
      centerline, above the deck-plates, running at an upward angle as it enters
      the chamber (so that water splashed on the hole will run out and not enter
      the chamber) would be the simplest solution...

      Thanks all,
      --
      Curran Bishop

      " 'Round our boat be God's aboutness,
      'er we try the depth of sea,
      egg-shell frail for all her stoutness
      unless Thou her helmsman be."
      -- Old Scottish Prayer


      [Non-text portions of this message have been removed]
    • Anders Bjorklund
      Sounds good to me. Are your buoyancy chamber deck plates located where they wouldn t admit water if you just drilled your holes through their cover plates
      Message 2 of 8 , Jul 22 10:56 PM
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        Sounds good to me. Are your buoyancy chamber deck plates located where they
        wouldn't admit water if you just drilled your holes through their cover
        plates themselves?

        Anders


        On Mon, Jul 22, 2013 at 11:30 PM, Curran Bishop <curranb79@...> wrote:

        > I was talking to a guy who was admiring the AF4 and he said he had built
        > fiberglass johnboats and warned me to make sure the buoyancy chambers had a
        > means of breathing. He pointed out that with the way I have mine set up
        > with pop-out deck-plates to keep them water-tight the sun hitting the sides
        > of them can heat the air inside and make it expand, compromising the seams
        > of the chambers. While I store and transport the boat with the deck-plates
        > open, there is still opportunity for heating when the boat's in use - how
        > serious a concern is this?
        >
        > I've been thinking something along the lines of a 1/8" hole on the boat's
        > centerline, above the deck-plates, running at an upward angle as it enters
        > the chamber (so that water splashed on the hole will run out and not enter
        > the chamber) would be the simplest solution...
        >
        > Thanks all,
        > --
        > Curran Bishop
        >


        [Non-text portions of this message have been removed]
      • John Trussell
        I don t believe it takes a very big hole to vent air pressure due to expansion of air. While such small holes let air out, they won t let significant amounts
        Message 3 of 8 , Jul 23 4:55 AM
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          I don't believe it takes a very big hole to vent air pressure due to
          expansion of air. While such small holes let air out, they won't let
          significant amounts of water in, particularly if there was not another vent
          hole to let the compressing air out! Even then, you are talking about water
          dripping and it would probably be a long time before there was enough water
          in the tank to compromise flotation.



          The concern about expansion while the boat is in use is probably overblown
          and varies with deck color, climate, and the proximity of the tank to water.




          I live in the south and I have not yet had a cover blow out or chamber seams
          open up. Maybe my experience is typical or maybe I've been lucky. Anyone
          else having problems?



          JOhnT



          _____

          From: Michalak@yahoogroups.com [mailto:Michalak@yahoogroups.com] On Behalf
          Of Curran Bishop
          Sent: Tuesday, July 23, 2013 12:31 AM
          To: Michalak
          Subject: [Michalak] letting buoyancy chambers breath?





          I was talking to a guy who was admiring the AF4 and he said he had built
          fiberglass johnboats and warned me to make sure the buoyancy chambers had a
          means of breathing. He pointed out that with the way I have mine set up
          with pop-out deck-plates to keep them water-tight the sun hitting the sides
          of them can heat the air inside and make it expand, compromising the seams
          of the chambers. While I store and transport the boat with the deck-plates
          open, there is still opportunity for heating when the boat's in use - how
          serious a concern is this?

          I've been thinking something along the lines of a 1/8" hole on the boat's
          centerline, above the deck-plates, running at an upward angle as it enters
          the chamber (so that water splashed on the hole will run out and not enter
          the chamber) would be the simplest solution...

          Thanks all,
          --
          Curran Bishop

          " 'Round our boat be God's aboutness,
          'er we try the depth of sea,
          egg-shell frail for all her stoutness
          unless Thou her helmsman be."
          -- Old Scottish Prayer

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





          [Non-text portions of this message have been removed]
        • Joseph Stromski
          I ve never had an issue, but its very likely the hinged deck hatch I m using is less than 100% watertight. The small hole would work, or if you want to go all
          Message 4 of 8 , Jul 23 5:42 AM
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            I've never had an issue, but its very likely the hinged deck hatch I'm using is less than 100% watertight. The small hole would work, or if you want to go all fancy I suppose a surfboard GoreTex vent could work too
            http://www.foamez.com/ez-retrofit-vent-plug-selfventing-p-875.html


            Best,
            Joe


            ________________________________
            From: John Trussell <jtrussell2@...>
            To: Michalak@yahoogroups.com
            Sent: Tuesday, July 23, 2013 6:55 AM
            Subject: RE: [Michalak] letting buoyancy chambers breath?



             
            I don't believe it takes a very big hole to vent air pressure due to
            expansion of air. While such small holes let air out, they won't let
            significant amounts of water in, particularly if there was not another vent
            hole to let the compressing air out! Even then, you are talking about water
            dripping and it would probably be a long time before there was enough water
            in the tank to compromise flotation.

            The concern about expansion while the boat is in use is probably overblown
            and varies with deck color, climate, and the proximity of the tank to water.

            I live in the south and I have not yet had a cover blow out or chamber seams
            open up. Maybe my experience is typical or maybe I've been lucky. Anyone
            else having problems?

            JOhnT

            _____

            From: Michalak@yahoogroups.com [mailto:Michalak@yahoogroups.com] On Behalf
            Of Curran Bishop
            Sent: Tuesday, July 23, 2013 12:31 AM
            To: Michalak
            Subject: [Michalak] letting buoyancy chambers breath?

            I was talking to a guy who was admiring the AF4 and he said he had built
            fiberglass johnboats and warned me to make sure the buoyancy chambers had a
            means of breathing. He pointed out that with the way I have mine set up
            with pop-out deck-plates to keep them water-tight the sun hitting the sides
            of them can heat the air inside and make it expand, compromising the seams
            of the chambers. While I store and transport the boat with the deck-plates
            open, there is still opportunity for heating when the boat's in use - how
            serious a concern is this?

            I've been thinking something along the lines of a 1/8" hole on the boat's
            centerline, above the deck-plates, running at an upward angle as it enters
            the chamber (so that water splashed on the hole will run out and not enter
            the chamber) would be the simplest solution...

            Thanks all,
            --
            Curran Bishop

            " 'Round our boat be God's aboutness,
            'er we try the depth of sea,
            egg-shell frail for all her stoutness
            unless Thou her helmsman be."
            -- Old Scottish Prayer

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

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




            [Non-text portions of this message have been removed]
          • jhargrovewright2@juno.com
            John, I understand the concern / theory, that some have and it sounds reasonable to worry about the problem, BUT, my empirical data over many years and many
            Message 5 of 8 , Jul 23 6:05 AM
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              John, I understand the concern / theory, that some have and it sounds reasonable to worry about "the" problem, BUT, my empirical data over many years and many boats says one or a combination of things. My builds suck thereby letting air in and out unintentionally.... or some other mechanism is taking care of me? us? I suspect that there is no such thing as an air proof inspection hatch, but that is just a guess. JIB "I don't worry about things that go bump in the night....just the things that bump me in the daylight..."

              ---------- Original Message ----------
              From: "John Trussell" <jtrussell2@...>
              To: <Michalak@yahoogroups.com>
              Subject: RE: [Michalak] letting buoyancy chambers breath?
              Date: Tue, 23 Jul 2013 07:55:57 -0400



              I don't believe it takes a very big hole to vent air pressure due to
              expansion of air. While such small holes let air out, they won't let
              significant amounts of water in, particularly if there was not another vent
              hole to let the compressing air out! Even then, you are talking about water
              dripping and it would probably be a long time before there was enough water
              in the tank to compromise flotation.

              The concern about expansion while the boat is in use is probably overblown
              and varies with deck color, climate, and the proximity of the tank to water.

              I live in the south and I have not yet had a cover blow out or chamber seams
              open up. Maybe my experience is typical or maybe I've been lucky. Anyone
              else having problems?

              JOhnT

              _____

              From: Michalak@yahoogroups.com [mailto:Michalak@yahoogroups.com] On Behalf
              Of Curran Bishop
              Sent: Tuesday, July 23, 2013 12:31 AM
              To: Michalak
              Subject: [Michalak] letting buoyancy chambers breath?

              I was talking to a guy who was admiring the AF4 and he said he had built
              fiberglass johnboats and warned me to make sure the buoyancy chambers had a
              means of breathing. He pointed out that with the way I have mine set up
              with pop-out deck-plates to keep them water-tight the sun hitting the sides
              of them can heat the air inside and make it expand, compromising the seams
              of the chambers. While I store and transport the boat with the deck-plates
              open, there is still opportunity for heating when the boat's in use - how
              serious a concern is this?

              I've been thinking something along the lines of a 1/8" hole on the boat's
              centerline, above the deck-plates, running at an upward angle as it enters
              the chamber (so that water splashed on the hole will run out and not enter
              the chamber) would be the simplest solution...

              Thanks all,
              --
              Curran Bishop

              " 'Round our boat be God's aboutness,
              'er we try the depth of sea,
              egg-shell frail for all her stoutness
              unless Thou her helmsman be."
              -- Old Scottish Prayer

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

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







              [Non-text portions of this message have been removed]
            • John Boy
              I live in the FL Panhandle and I ve never had a problem.  I normally store my boats with the deck plates open to promote air circulation.  Come to think of
              Message 6 of 8 , Jul 23 7:52 AM
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                I live in the FL Panhandle and I've never had a problem.  I normally store my boats with the deck plates open to promote air circulation.  Come to think of it, I just remembered to open my deckplate in my bow compartment.  It's been installed since May.  No factor.
                John Boy 
                 



                “Seaward ho! Hang the treasure! It's the glory of the sea that has turned my head.” 

                Robert Louis Stevenson, Treasure Island


                ________________________________
                From: John Trussell <jtrussell2@...>
                To: Michalak@yahoogroups.com
                Sent: Tuesday, July 23, 2013 6:55 AM
                Subject: RE: [Michalak] letting buoyancy chambers breath?



                 
                I don't believe it takes a very big hole to vent air pressure due to
                expansion of air. While such small holes let air out, they won't let
                significant amounts of water in, particularly if there was not another vent
                hole to let the compressing air out! Even then, you are talking about water
                dripping and it would probably be a long time before there was enough water
                in the tank to compromise flotation.

                The concern about expansion while the boat is in use is probably overblown
                and varies with deck color, climate, and the proximity of the tank to water.

                I live in the south and I have not yet had a cover blow out or chamber seams
                open up. Maybe my experience is typical or maybe I've been lucky. Anyone
                else having problems?

                JOhnT

                _____

                From: Michalak@yahoogroups.com [mailto:Michalak@yahoogroups.com] On Behalf
                Of Curran Bishop
                Sent: Tuesday, July 23, 2013 12:31 AM
                To: Michalak
                Subject: [Michalak] letting buoyancy chambers breath?

                I was talking to a guy who was admiring the AF4 and he said he had built
                fiberglass johnboats and warned me to make sure the buoyancy chambers had a
                means of breathing. He pointed out that with the way I have mine set up
                with pop-out deck-plates to keep them water-tight the sun hitting the sides
                of them can heat the air inside and make it expand, compromising the seams
                of the chambers. While I store and transport the boat with the deck-plates
                open, there is still opportunity for heating when the boat's in use - how
                serious a concern is this?

                I've been thinking something along the lines of a 1/8" hole on the boat's
                centerline, above the deck-plates, running at an upward angle as it enters
                the chamber (so that water splashed on the hole will run out and not enter
                the chamber) would be the simplest solution...

                Thanks all,
                --
                Curran Bishop

                " 'Round our boat be God's aboutness,
                'er we try the depth of sea,
                egg-shell frail for all her stoutness
                unless Thou her helmsman be."
                -- Old Scottish Prayer

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

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




                [Non-text portions of this message have been removed]
              • prairiedog2332
                My thinking is that if you build the hatch covers according to Jim s instructions (secured with shock cord) there should never be a problem. As air pressure
                Message 7 of 8 , Jul 23 8:21 AM
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                  My thinking is that if you build the hatch covers according to Jim's
                  instructions (secured with shock cord) there should never be a problem.
                  As air pressure builds up in the flotation chamber, the cover should
                  raise up slightly and release the hot air pressure long before the
                  seams blow. Then once out on the water the air will likely cool and
                  contract, locking the hatch cover even tighter.

                  Always best to have lighter colored boat decks, but not blinding white.

                  Nels

                  --- In Michalak@yahoogroups.com, John Boy wrote:
                  >
                  > I live in the FL Panhandle and I've never had a problem. Â I
                  normally store my boats with the deck plates open to promote air
                  circulation. Â Come to think of it, I just remembered to open my
                  deckplate in my bow compartment. Â It's been installed since May.
                  Â No factor.
                  > John BoyÂ




                  [Non-text portions of this message have been removed]
                • John
                  I have only seen the need to vent air chambers on 1 type boat, the Olympic Class Tornado built by the Gougeon Brothers in the mid 1970 s. In the first Tornado
                  Message 8 of 8 , Jul 23 11:52 AM
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                    I have only seen the need to vent air chambers on 1 type boat, the Olympic Class Tornado built by the Gougeon Brothers in the mid 1970's. In the first Tornado they build there was an expansion failure when the air in the hull heated up and broke/sheared a piece of blocking at some cross bracing deep inside the hull. These boats were built so precisely no inspection ports were installed at the factory because they didn't leak. The solution was a very small aluminum vent alum tube, 1/16 ID, installed and hidden inside the front beam so the air pressure could equalize. The tube was considered so small that in the event of capsize the hydrostatic pressure could not overwhelm the air pressure inside the hull.

                    When inspection ports were installed later we took to "burping" the hulls by opening the inspection ports to equilize the air after the boat was launched. We were carefull to do this when the boat had been sitting in a hot parking lot and then getting tossed into really cold water like Lake Ontario. This "burping" helped the air chamber vent do it's job faster.

                    As for my homebuilt Goat Island Skiff and Hapscut where my hatches are homebuilt and are nowhere near as tight as a Gougeon built boat, I don't worry about it.

                    JDG





                    --- In Michalak@yahoogroups.com, Curran Bishop <curranb79@...> wrote:
                    >
                    > I was talking to a guy who was admiring the AF4 and he said he had built
                    > fiberglass johnboats and warned me to make sure the buoyancy chambers had a
                    > means of breathing. He pointed out that with the way I have mine set up
                    > with pop-out deck-plates to keep them water-tight the sun hitting the sides
                    > of them can heat the air inside and make it expand, compromising the seams
                    > of the chambers. While I store and transport the boat with the deck-plates
                    > open, there is still opportunity for heating when the boat's in use - how
                    > serious a concern is this?
                    >
                    > I've been thinking something along the lines of a 1/8" hole on the boat's
                    > centerline, above the deck-plates, running at an upward angle as it enters
                    > the chamber (so that water splashed on the hole will run out and not enter
                    > the chamber) would be the simplest solution...
                    >
                    > Thanks all,
                    > --
                    > Curran Bishop
                    >
                    > " 'Round our boat be God's aboutness,
                    > 'er we try the depth of sea,
                    > egg-shell frail for all her stoutness
                    > unless Thou her helmsman be."
                    > -- Old Scottish Prayer
                    >
                    >
                    > [Non-text portions of this message have been removed]
                    >
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