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Re: Commonsense Skiff

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  • graeme19121984
    Hi Gary, I just realised from here: (see pp 3 & 9) http://www.boatdesign.com/postings/Files/instbb/ib9.pdf that Jinni is a plumb-sided squareboat. Slightly
    Message 1 of 20 , Jul 1, 2005
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      Hi Gary, I just realised from here: (see pp 3 & 9)

      http://www.boatdesign.com/postings/Files/instbb/ib9.pdf

      that "Jinni" is a plumb-sided squareboat. Slightly bigger than "June
      Bug" eh? Pretty. Fast. Camp space for two, a tent that could also
      cover both fore and aft storage compartents without the rainwater
      runs from a mast stepped in the forward well.

      Apparently Bolger mods include solent lug (easier reefing), lee
      boards, and
      Jim Michalak's mods of pivoting lee board/rudder, and balanced lug
      (easier reefing but rainwater dowm mast).

      Pre-glassed foam panels, cut and glued? Easy and quick build; but
      may exceed your 80lbs limit? Wooboo also takes six sheets of ply, I
      think.

      graeme


      --- In bolger@yahoogroups.com, "gbship" <gbship@c...> wrote:
      > Graeme:
      >
      > Thanks. Found them. That beach cruiser is interesting. I'm looking
      > for womething that can be built of foam/epoxy/glass instead of
      > ply/glass for an ultra-light boat, hopefully in the 70-80 pound
      > range. Candidates are these two boats, Michalak's Woodbo, and
      maybe
      > Gypsy, with some modifications (I want a reefing sail and room to
      > sleep on board under a boom tent. Not sure the Beach Cruiser could
      be
      > done light enough, but it sure is a seductive design.
      >
      > Gary
      >
      > --- In bolger@yahoogroups.com, "graeme19121984"
      <graeme19121984@y...>
      > wrote:
      > > Gary,
      > > if you look in this group's files under Perfect Skiff, or here:
      > >
      > > http://groups.yahoo.com/group/bolger/files/Perfect%20Skiff/
      > >
      > > The boats here, 'CSD Skiff', and 'Beach Cruiser Concept', are
      > great!
      > > PCB writes 'BCC' can sail through very rough water, including
      surf.
      > > What's rougher than surf :)?
      > >
      > > I'm inclined to prefer the 'BCC'. Is it a kind of
      > > stretched'n'decked 'Jinni'? (not many images around of 'Jinni',
      > > especially plan view, though the design is refered to plenty.
      Its
      > in
      > > an old book I've been unable to get yet.)
      > >
      > > Do you know if PCB proved the concept of 'BCC'? Has done a
      design
      > > (perhaps for the allegedly infamous Woodenboat magazine early
      > > 90's "Perfect Skiff Competition")? Or are the compromises (to
      power
      > > etc)in 'CSD Skiff' it?
      > >
      > > cheers
      > > graeme
      > >
      > > --- In bolger@yahoogroups.com, "gbship" <gbship@c...> wrote:
      > > > Does anyone know of a link to pictures/plans for the
      Commonsense
      > > Skiff,
      > > > a rowing/sailing/power combo that Bolger drew several years
      ago?
      > > >
      > > > Thanks
      > > >
      > > > Gary Blankenship
    • graeme19121984
      Actually, is the Jinny hull a slightly bigger June Bug , or a re- worked Cold Water Sailboard (Chapter 5 FS)? I ve thought about camper mods to CWS .
      Message 2 of 20 , Jul 1, 2005
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        Actually, is the "Jinny" hull a slightly bigger "June Bug", or a re-
        worked "Cold Water Sailboard" (Chapter 5 FS)?

        I've thought about camper mods to "CWS".

        cheers
        graeme


        --- In bolger@yahoogroups.com, "graeme19121984" <graeme19121984@y...>
        wrote:
        > Hi Gary, I just realised from here: (see pp 3 & 9)
        >
        > http://www.boatdesign.com/postings/Files/instbb/ib9.pdf
        >
        > that "Jinni" is a plumb-sided squareboat. Slightly bigger than "June
        > Bug" eh? Pretty. Fast.
      • Chris Lasdauskas
        ... Gary, I forget the details, but a few years ago I sat down and worked out the weight for Gypsy built out of various types of Ply and alternatively from
        Message 3 of 20 , Jul 2, 2005
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          gbship wrote:

          > Graeme:
          >
          > Thanks. Found them. That beach cruiser is interesting. I'm looking
          > for womething that can be built of foam/epoxy/glass instead of
          > ply/glass for an ultra-light boat, hopefully in the 70-80 pound
          > range. Candidates are these two boats, Michalak's Woodbo, and maybe
          > Gypsy, with some modifications (I want a reefing sail and room to
          > sleep on board under a boom tent. Not sure the Beach Cruiser could be
          > done light enough, but it sure is a seductive design.
          >
          > Gary


          Gary,
          I forget the details, but a few years ago I sat down and worked out the
          weight for Gypsy built out of various types of Ply and alternatively
          from glassed foam. The foam was heavier than at least the lightest
          (possibly all) ply variation.

          I vaguely recall the issue was getting reasonable penetration protection.

          Chris
        • gbship
          Graeme, I m not sure Jimmi would row as well as the others, although it would be a possibility. It would be a better bet if two of us do this competition
          Message 4 of 20 , Jul 2, 2005
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            Graeme, I'm not sure Jimmi would row as well as the others, although it
            would be a possibility. It would be a better bet if two of us do this
            competition instead of me doing it solo. I would tend to think a multi-
            chine like Gypsy or Woodbo would be better, or if it's a sharpie hull,
            it would have to be faily narrow for its length, like the Beach Cruiser.

            Chris: How do you figure scantlings for foam/glass construction? I've
            done some online looking, but haven't found any resources. A friend
            laminated a couple layers of glass on either side of 3/8 inch foam (I
            think that was the thickness) and you could whack it with a hammer
            without damage and it was considerably lighter than a ply sandwich
            would have been. I made some hatches for our Frolic2 of glass over 1/4-
            inch foam and those are reasonably strong, and very light, but not
            strong enough for use for a hull. I have no idea if I should use
            thicker foam, more glass, or both for suitable strength. For that
            matter, if the budget allows, it's possible I'll got to carbon
            fiber/foam, which should be even lighter, but again, I have no idea of
            the suitable scantlings....

            Gary
          • graeme19121984
            Gary, competition changes things. IIRC Tom F Jones in Low Resistance Boats wrote of a
            Message 5 of 20 , Jul 2, 2005
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              Gary, "competition" changes things. IIRC Tom F Jones in "Low
              Resistance Boats" wrote of a <100 lbs garvey he once designed for a
              week-or-so long beachcruising race in which boats (solo) had to
              carry all their necessaries, and be able to be beached well above
              high water by their crew without any assistance of any kind each
              night. I liked the idea of that little cute sneakbox style 3/4
              decked cruiser a lot, and swear I would have built one if Jones
              published plans. Its owner loved it and enjoyed lengthy cruises and
              messing about in it for many years. It was no racer though. A wiser
              Jones wrote that if he had to do it again for that type of
              competition he would design something minimumalist canoe like. The
              sailing was not quite as important a factor as lightness and rowing.

              How about an adjusted "Zephyr" for two? length/beam > 6/1. (with
              reduced scantlings? Anhinga at 23'5" has only 0.25" ply sides)

              graeme

              --- In bolger@yahoogroups.com, "gbship" <gbship@c...> wrote:
              > Graeme, I'm not sure Jimmi would row as well as the others,
              although it
              > would be a possibility. It would be a better bet if two of us do
              this
              > competition instead of me doing it solo. I would tend to think a
              multi-
              > chine like Gypsy or Woodbo would be better, or if it's a sharpie
              hull,
              > it would have to be faily narrow for its length, like the Beach
              Cruiser.
              >
              > Chris: How do you figure scantlings for foam/glass construction?
              I've
              > done some online looking, but haven't found any resources. A
              friend
              > laminated a couple layers of glass on either side of 3/8 inch foam
              (I
              > think that was the thickness) and you could whack it with a hammer
              > without damage and it was considerably lighter than a ply sandwich
              > would have been. I made some hatches for our Frolic2 of glass over
              1/4-
              > inch foam and those are reasonably strong, and very light, but not
              > strong enough for use for a hull. I have no idea if I should use
              > thicker foam, more glass, or both for suitable strength. For that
              > matter, if the budget allows, it's possible I'll got to carbon
              > fiber/foam, which should be even lighter, but again, I have no
              idea of
              > the suitable scantlings....
              >
              > Gary
            • Howard Stephenson
              Gary, If you go to: http://boatdesign.net/forums/archive/index.php/t-6334 .. you will find useful guidance on foam/glass scantlings. Following the advice
              Message 6 of 20 , Jul 2, 2005
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                Gary,

                If you go to:

                http://boatdesign.net/forums/archive/index.php/t-6334

                .. you will find useful guidance on foam/glass scantlings. Following
                the advice there, you should be able to decide what your scantlings
                would need to be and then compare the calculated weight per unit area
                with that of a ply skin -- and compare the cost too!

                Howard

                --- In bolger@yahoogroups.com, "gbship" <gbship@c...> wrote:> Chris:
                How do you figure scantlings for foam/glass construction? I've
                > done some online looking, but haven't found any resources.
              • Chris Lasdauskas
                ... Gary, as I said it was a few years back, so this may not be right, but I think I used The Elements of Boat Strength for Builders, Designers, and Owners
                Message 7 of 20 , Jul 2, 2005
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                  gbship wrote:
                  >
                  > Chris: How do you figure scantlings for foam/glass construction? I've
                  > done some online looking, but haven't found any resources.

                  Gary, as I said it was a few years back, so this may not be right, but I
                  think I used "The Elements of Boat Strength for Builders, Designers, and
                  Owners" by Dave Gerr (though that is copyright 2000, and I thought I did
                  this in about 1999..., perhaps I used his "The Nature of Boats"), I
                  think I also didn't find much online.

                  > A friend
                  > laminated a couple layers of glass on either side of 3/8 inch foam (I
                  > think that was the thickness) and you could whack it with a hammer
                  > without damage and it was considerably lighter than a ply sandwich
                  > would have been.

                  Which reminds me of this cautionary story from "The Nature of Boats":

                  'A Warning About Being Thin-Skinned

                  'A final word of warning is in order. When using these high-strength
                  fibers and sandwich construction, the skin thickness required for
                  overall —- remember overall -— structural strength can become almost
                  unbelievably thin, even on quite large vessels. This works out well on
                  paper, but what about hitting a floating log? A well-known designer
                  related a story both amusing and worrisome. A local builder of large
                  (90-foot, 27-meter) high-speed sportfishermen proudly showed him an
                  all-Kevlar, foam-sandwich hull panel that he'd used in a couple of
                  recent craft. The builder explained that his computer confirmed the
                  very, very thin skins (on the inside and outside of the foam) were more
                  than up to the job.

                  'To demonstrate his point, the builder took a hammer and wacked at the
                  sample panel mightily. With the hammer bouncing off harmlessly, he
                  offered it confidently to the skeptical architect. Taking the hammer,
                  the architect turned it claw-side down and -— with virtually no force at
                  all -— drove it right through Kevlar, the foam, and out the other side.
                  The builder's face turned white. He had a couple of boats out on the
                  water with this layup. The moral -— there's always a moral -— is that
                  the structural design of high-tech hulls is a complicated business.
                  Before you dash off to build or have built one of these miracle hulls,
                  make sure a good naval architect does a detailed structural analysis.'

                  That's what I was talking about when I mentioned penetration strength.
                  Sure a Gypsy isn't going to hit logs at 30 knots, but the scantlings
                  will already be redeuced in proportion to the speed. You can't let the
                  skins get too thin. 'Too thin' on foam is thinnner than 'too thin' on
                  ply. Avoiding that was where the extra weight came from.

                  Chris
                • gbship
                  ... strength. ... the ... Thanks everyone for the thought and advice. I should have explained better the use for this boat. It s for an expedition type
                  Message 8 of 20 , Jul 3, 2005
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                    >
                    > That's what I was talking about when I mentioned penetration
                    strength.
                    > Sure a Gypsy isn't going to hit logs at 30 knots, but the scantlings
                    > will already be redeuced in proportion to the speed. You can't let
                    the
                    > skins get too thin. 'Too thin' on foam is thinnner than 'too thin' on
                    > ply. Avoiding that was where the extra weight came from.
                    >
                    > Chris

                    Thanks everyone for the thought and advice. I should have explained
                    better the use for this boat. It's for an expedition type competition
                    of around 1,000 miles, give or take, for kayaks and small sailboats.
                    Among the salient features, are you must beach launch your craft (You
                    can use mechanical assistance, but you must carry whatever you use for
                    the entire race), the ability to go under a 9-foot high bridge with 10-
                    foot horizontal clearance, deal with open water and inland waterways
                    churned by powerboat wakes, etc. This race is around the peninsula part
                    of Florida, so at one point, competitors have to go up the St. Mary's
                    river (in S. Georgia) and then portage their boats 40 MILES to the
                    Suwanee. The kayakers balance their boats on a set of wheels, attach
                    the bow to the back of their belt and walk it. They can also tow it
                    with a folding bike -- as long as they carry the bike for the entire
                    race. Obviously this won't work for sailboats, which even in a small
                    size weigh much more. So those comeptitors are allowed to switch to a
                    canoe for the necessary river portions and the portage. You can see the
                    details at Watertribe.com, check the Ultra Florida Challenge section.
                    We're only planning to do the shorter Everglades Challenge in 2006, in
                    our Frolic2, but I'm intrigued with trying the longer race in 2007. My
                    particular itch right now is to wonder if a small sailboat could be
                    built light enough so that switching to the canoe would be unnecessary,
                    even for the portage (which I would do with a bike!).

                    But, alas, I know almost nothing of composite construction, which is
                    why everyone's advice is so helpful and much appreciated. It does no
                    good to have an ultralight hull if it's punctured by a razor sharp
                    shell on an oyster bar, or a cypress knee or mangrove root in the
                    Everglades, or by a rock or log in the Suwanee. The weight concern is
                    why I've been mostly looking at ply instant-type boats in the 125 to
                    150 pound range and wondering if that weight could be cut in half with
                    composite construction. There are intriguing hints. For example, my 25-
                    30 pound solid wood mast on the Rolic2 could be replaced by a carbon
                    fiber spar that would weight less than 10 pounds. In Pete Goss' book
                    about single handed racing around the world, he mentions that the bare
                    hull of his 50 footer could be turned over by 6 husky guys --- about
                    what the 1/2 inch ply/fiberglass bare hull weighs on our 30-footer
                    (which is a Gypsy-type hull).

                    BTW Graeme, thanks for the suggestion of the Zephyr, but I ruled that
                    out because while it is an excellent daysailer and can handle some
                    nasty weather, it doesn't row very well, possibly because the 16-inch
                    sides are too high. (I had one for many years, and was very fond of it.)

                    Gary Blankenship
                  • John B. Trussell
                    There have been various threads wich suggest that PCB doesn t design racing boats. You might take a look at Paul Gartside s web site--His Flashboat is a
                    Message 9 of 20 , Jul 3, 2005
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                      There have been various threads wich suggest that PCB doesn't design
                      "racing" boats. You might take a look at Paul Gartside's web site--His
                      Flashboat is a very light, very fast row boat and he has camp cruised around
                      Alaska in it.

                      It appears to me that the rules you described favor a kayak with a sail.
                      I've always thought that a two person rowing boat would do well in this sort
                      of race--the two rowers could alternate and maintain speed more or less
                      continuously; they would also have the ability to row together and buck
                      currents if needed.

                      I'm way too old and decrepit to participate or even enjoy the kind of boat
                      needed for this kind of event, but iy si fun to think about.

                      John T
                      ----- Original Message -----
                      From: "gbship" <gbship@...>
                      To: <bolger@yahoogroups.com>
                      Sent: Sunday, July 03, 2005 7:57 AM
                      Subject: [bolger] Re: Commonsense Skiff


                      > >
                      > > That's what I was talking about when I mentioned penetration
                      > strength.
                      > > Sure a Gypsy isn't going to hit logs at 30 knots, but the scantlings
                      > > will already be redeuced in proportion to the speed. You can't let
                      > the
                      > > skins get too thin. 'Too thin' on foam is thinnner than 'too thin' on
                      > > ply. Avoiding that was where the extra weight came from.
                      > >
                      > > Chris
                      >
                      > Thanks everyone for the thought and advice. I should have explained
                      > better the use for this boat. It's for an expedition type competition
                      > of around 1,000 miles, give or take, for kayaks and small sailboats.
                      > Among the salient features, are you must beach launch your craft (You
                      > can use mechanical assistance, but you must carry whatever you use for
                      > the entire race), the ability to go under a 9-foot high bridge with 10-
                      > foot horizontal clearance, deal with open water and inland waterways
                      > churned by powerboat wakes, etc. This race is around the peninsula part
                      > of Florida, so at one point, competitors have to go up the St. Mary's
                      > river (in S. Georgia) and then portage their boats 40 MILES to the
                      > Suwanee. The kayakers balance their boats on a set of wheels, attach
                      > the bow to the back of their belt and walk it. They can also tow it
                      > with a folding bike -- as long as they carry the bike for the entire
                      > race. Obviously this won't work for sailboats, which even in a small
                      > size weigh much more. So those comeptitors are allowed to switch to a
                      > canoe for the necessary river portions and the portage. You can see the
                      > details at Watertribe.com, check the Ultra Florida Challenge section.
                      > We're only planning to do the shorter Everglades Challenge in 2006, in
                      > our Frolic2, but I'm intrigued with trying the longer race in 2007. My
                      > particular itch right now is to wonder if a small sailboat could be
                      > built light enough so that switching to the canoe would be unnecessary,
                      > even for the portage (which I would do with a bike!).
                      >
                      > But, alas, I know almost nothing of composite construction, which is
                      > why everyone's advice is so helpful and much appreciated. It does no
                      > good to have an ultralight hull if it's punctured by a razor sharp
                      > shell on an oyster bar, or a cypress knee or mangrove root in the
                      > Everglades, or by a rock or log in the Suwanee. The weight concern is
                      > why I've been mostly looking at ply instant-type boats in the 125 to
                      > 150 pound range and wondering if that weight could be cut in half with
                      > composite construction. There are intriguing hints. For example, my 25-
                      > 30 pound solid wood mast on the Rolic2 could be replaced by a carbon
                      > fiber spar that would weight less than 10 pounds. In Pete Goss' book
                      > about single handed racing around the world, he mentions that the bare
                      > hull of his 50 footer could be turned over by 6 husky guys --- about
                      > what the 1/2 inch ply/fiberglass bare hull weighs on our 30-footer
                      > (which is a Gypsy-type hull).
                      >
                      > BTW Graeme, thanks for the suggestion of the Zephyr, but I ruled that
                      > out because while it is an excellent daysailer and can handle some
                      > nasty weather, it doesn't row very well, possibly because the 16-inch
                      > sides are too high. (I had one for many years, and was very fond of it.)
                      >
                      > Gary Blankenship
                      >
                      >
                      >
                      >
                      > Bolger rules!!!
                      > - no cursing, flaming, trolling, spamming, or flogging dead horses
                      > - stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
                      > - Pls add your comments at the TOP, SIGN your posts, and snip away
                      > - Plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA, 01930, Fax:
                      (978) 282-1349
                      > - Unsubscribe: bolger-unsubscribe@yahoogroups.com
                      > - Open discussion: bolger_coffee_lounge-subscribe@yahoogroups.com
                      > Yahoo! Groups Links
                      >
                      >
                      >
                      >
                      >
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                      >
                      >
                      > --
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                      >
                    • Gary Lepak
                      Gary, For what it s worth, I once built a Bolger Dolphin, (Small Boats, Design #259, 18 x 4 ) out of 3/8 Airex foam with two layers of 6 oz glass inside and
                      Message 10 of 20 , Jul 3, 2005
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                        Gary,

                        For what it's worth, I once built a Bolger Dolphin, (Small Boats, Design
                        #259, 18' x 4') out of 3/8" Airex foam with two layers of 6 oz glass inside
                        and out. It was a stripped down rowboat version, no centerboard, rudder or
                        rig. It weighed about a 100 lbs. I never weighed it, but two people could
                        throw it over their heads like a canoe. It seemed quite tough, and I never
                        worried about punctures or breakage. Of course it is a compound curved
                        hull so the bulding took some time with lofting and moldmaking, but you
                        would get a strong light hull this way. These days I would use Corefoam,
                        though it is expensive.

                        For a cheaper light boat that would be quicker to build I might try
                        lapstrake plywood. You could vary the plank thickness, say 4 to 5 mm on the
                        bottom and 3mm topsides.

                        Gary Lepak
                        Port Angeles, WA
                      • Howard Stephenson
                        To see a boat that is suitable for South Georgia, go to: http://www.ibiblio.org/ebooks/Shackleton/South/057.jpg Howard ;-]
                        Message 11 of 20 , Jul 3, 2005
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                          To see a boat that is suitable for South Georgia, go to:

                          http://www.ibiblio.org/ebooks/Shackleton/South/057.jpg

                          Howard ;-]

                          --- In bolger@yahoogroups.com, "gbship" <gbship@c...> wrote:

                          > so at one point, competitors have to go up the St. Mary's
                          > river (in S. Georgia) and then portage their boats 40 MILES
                        • graeme19121984
                          Perhaps *the* small boat team time trial endurance event.
                          Message 12 of 20 , Jul 3, 2005
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                            Perhaps *the* small boat team time trial endurance event.

                            --- In bolger@yahoogroups.com, "Howard Stephenson" <stephensonhw@a...>
                            wrote:
                            > To see a boat that is suitable for South Georgia, go to:
                            >
                            > http://www.ibiblio.org/ebooks/Shackleton/South/057.jpg
                            >
                            > Howard ;-]
                            >
                            > --- In bolger@yahoogroups.com, "gbship" <gbship@c...> wrote:
                            >
                            > > so at one point, competitors have to go up the St. Mary's
                            > > river (in S. Georgia) and then portage their boats 40 MILES
                          • James Greene
                            Wow, when I was thinking abut glass over foam construction I was considering 1 inch foam or thicker for the hulls. You guys are using foam that s less than
                            Message 13 of 20 , Jul 3, 2005
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                              Wow, when I was thinking abut glass over foam construction I was
                              considering 1 inch foam or thicker for the hulls. You guys are using
                              foam that's less than half this thickness! Interesting ...

                              James Greene


                              On Jul 3, 2005, at 09:58, gbship wrote:

                              > A friend
                              > laminated a couple layers of glass on either side of 3/8 inch foam (I
                              > think that was the thickness) and you could whack it with a hammer
                              > without damage and it was considerably lighter than a ply sandwich
                              > would have been. I made some hatches for our Frolic2 of glass over 1/4-
                              > inch foam and those are reasonably strong, and very light, but not
                              > strong enough for use for a hull.
                            • James Greene
                              ... I wonder if the cheapest available foam might not be good enough for most small boats, provided it fills the void between the inner and outer skins and
                              Message 14 of 20 , Jul 3, 2005
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                                > These days I would use Corefoam,
                                > though it is expensive.

                                I wonder if the cheapest available foam might not be "good enough" for
                                most small boats, provided it fills the void between the inner and
                                outer skins and does not separate from them. Does this leave out good
                                old fashioned styrofoam I wonder?

                                James Greene
                              • Clyde Wisner
                                I think I used inch and a half foam for my Brick and had to use a lot of glass and epoxy to get strength to stand in. I also made a deck of sorts from 1/4 ply
                                Message 15 of 20 , Jul 4, 2005
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                                  I think I used inch and a half foam for my Brick and had to use a lot of
                                  glass and epoxy to get strength to stand in. I also made a deck of sorts
                                  from 1/4 ply so the sides wouldn't bolge out. Overall, not worth the
                                  money in glass and epoxy, and the trouble. If you do go forward, I would
                                  think a multi
                                  chine rather than large flat areas like the bottom of a Brick. My foam
                                  Brick floats upside down of course and almost floated away during
                                  Isabell, which might not have been bad. Clyde.


                                  James Greene wrote:

                                  > > These days I would use Corefoam,
                                  > > though it is expensive.
                                  >
                                  > I wonder if the cheapest available foam might not be "good enough" for
                                  > most small boats, provided it fills the void between the inner and
                                  > outer skins and does not separate from them. Does this leave out good
                                  > old fashioned styrofoam I wonder?
                                  >
                                  > James Greene
                                  >
                                  >
                                  >
                                  >
                                  >
                                  >
                                  > Bolger rules!!!
                                  > - no cursing, flaming, trolling, spamming, or flogging dead horses
                                  > - stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
                                  > - Pls add your comments at the TOP, SIGN your posts, and snip away
                                  > - Plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA, 01930,
                                  > Fax: (978) 282-1349
                                  > - Unsubscribe: bolger-unsubscribe@yahoogroups.com
                                  > - Open discussion: bolger_coffee_lounge-subscribe@yahoogroups.com
                                  >
                                  >
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                                  [Non-text portions of this message have been removed]
                                • Chris Stewart
                                  ... the ... at ... side. Consider skin on frame constuction using 26 ounce double ply woven nylon skin. Quoting from UMIAK An Illustrated Guide by Skip
                                  Message 16 of 20 , Jul 4, 2005
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                                    --- In bolger@yahoogroups.com, Chris Lasdauskas <cml@t...> wrote:
                                    > 'To demonstrate his point, the builder took a hammer and wacked at
                                    the
                                    > sample panel mightily. With the hammer bouncing off harmlessly, he
                                    > offered it confidently to the skeptical architect. Taking the hammer,
                                    > the architect turned it claw-side down and -— with virtually no force
                                    at
                                    > all -— drove it right through Kevlar, the foam, and out the other
                                    side.


                                    Consider skin on frame constuction using 26 ounce double ply woven
                                    nylon skin. Quoting from "UMIAK An Illustrated Guide" by Skip Snaith:
                                    "The 26-ounce double-weave nylon skin on Tim's boat was incredibly
                                    tough; you could hit it with the claw end of a hammer as hard as you
                                    liked, and the hammer would bounce back."

                                    Skin on frame can produce very light boats. Platt Monfort's Geodesic
                                    Aerolight boats are incredibly light, but probably not strong enough
                                    for the Watertribe Challenge. Up the scantlings a bit, with the frame
                                    lashed rather than glued to preserve flexibility, and use a much
                                    tougher skin and you'd end up with a light, resilient boat.

                                    Chris Stewart
                                  • Gary Lepak
                                    James, The boatbuilding foams like Airex, Corecell and Divinicell are more dense than styrofoam. 5 to 8 lbs per cubic ft. compared to 1.1 (white) to 2 (pink
                                    Message 17 of 20 , Jul 4, 2005
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                                      James,
                                      The boatbuilding foams like Airex, Corecell and Divinicell are more dense
                                      than styrofoam. 5 to 8 lbs per cubic ft. compared to 1.1 (white) to 2
                                      (pink or blue). The lighter the foam the thicker the skin needs to be to
                                      maintain the bond when struck. I've built two boats from blue foam, a tri
                                      that didn't last very long made of 1" thick foam with glass/epoxy skins,
                                      and a solid foam paddleboard I still have. The board has two layers of 6
                                      oz glass in epoxy resin on the bottom and a 3mm ply deck. The two layers of
                                      6 are about minimum I think, and it is still easily punctured or dented. It
                                      just doesn't matter much if it is, as it still floats, being solid foam. If
                                      you are always building boats with epoxy anyway, you fill the dings easily.
                                      The ply deck seems to take a lot of abuse without delaminating though, and
                                      could make a good boat with 1" foam inside 3mm ply with glass inside, but
                                      would probably weigh as much as 1/4" ply. I like using the blue foam though
                                      and still use it for things like outrigger floats or sponsons, i.e. solid
                                      foam objects with glass skin, rather than as a foam sandwich hull skin .
                                      Gary Lepak


                                      ----- Original Message ----- > I wonder if the cheapest available foam might
                                      not be "good enough" for
                                      > most small boats, provided it fills the void between the inner and
                                      > outer skins and does not separate from them. Does this leave out good
                                      > old fashioned styrofoam I wonder?
                                      >
                                      > James Greene
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