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[bolger] Re: sharpie stability/recovery

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  • Richard
    ... A long, narrow, flat bottom boat would be very fast. Of course, you would have an interesting time turning it, to say nothing of trying to go through
    Message 1 of 12 , Jan 30, 2000
      Ron Badley wrote:

      >
      > > Why this? The more I read, the more beaminess seems like a liability.
      > > I'm beginning to suspect boat are made wide so as to make them easy
      > > to sell, not easy to sail. I can't help but wonder what you end up
      > > with if you design for maximum, rather than minimum waterline.
      > >
      > > Anyone want to kick this around?
      >
      >

      A long, narrow, flat bottom boat would be very fast. Of course, you would
      have an interesting time turning it, to say nothing of trying to go through
      stays.

      The beaminess is what give it the stability, that's why the hulls of a cat
      are so far apart. Mine is 5 ft wide and 20 ft long, for a 4:1 length to beam
      ratio. Say you went to the extreme, 3 feet wide and 30 feet long. Basicaly a
      very long canoe. It would be pretty fast, but very hard to turn. If you
      increase rocker to improve turning, you loose waterline....
    • David Ryan
      FBBB -- I ve been thinking a lot about stability and recovery, and studying BWAOM very hard, especially the AS29 and LooseMoose. I think I m finally starting
      Message 2 of 12 , Jan 31, 2000
        FBBB --

        I've been thinking a lot about stability and recovery, and studying
        BWAOM very hard, especially the AS29 and LooseMoose. I think I'm
        finally starting to get the shallow draft/high freeboard concept.

        Having spent my whole life sailing dingies, I have always equated
        stability with hiking over the side, and maybe a weighed
        centerboard. Recovery meant standing on the centerboard and prying
        the thing back to upright. In a larger boat, this seemed to
        *obviously* indicate the necessity of deep keels and heavy ballast.

        The AS29 and LM (if I understand correctly,) seem to prove otherwise,
        and I am very intrigued.

        I've spent the weekend imaging a crusing sharpie that takes the
        concept to extremes -- a very long, very slender craft sporting a low
        sail plan and high freeboard: sort of like an extrastretched
        tarantula (minus the keel) with a multi-mast sail plan and high
        topsides. At what point is the beam to freeboard ratio optimized?

        Why this? The more I read, the more beaminess seems like a liability.
        I'm beginning to suspect boat are made wide so as to make them easy
        to sell, not easy to sail. I can't help but wonder what you end up
        with if you design for maximum, rather than minimum waterline.

        Anyone want to kick this around?

        YIBB,

        David Ryan
        Minister of Information and Culture
        Crumbling Empire Productions
        (212) 247-0296
      • Ron Badley
        ... Snip ... You ll end up with a multihull ;-) Ron Kismet 31 Big Bird (trimaran, building a cat)
        Message 3 of 12 , Jan 31, 2000
          >From: David Ryan <david@...>

          > FBBB --
          >
          > I've been thinking a lot about stability and recovery, and studying
          > BWAOM very hard, especially the AS29 and LooseMoose. I think I'm
          > finally starting to get the shallow draft/high freeboard concept.

          Snip

          > Why this? The more I read, the more beaminess seems like a liability.
          > I'm beginning to suspect boat are made wide so as to make them easy
          > to sell, not easy to sail. I can't help but wonder what you end up
          > with if you design for maximum, rather than minimum waterline.
          >
          > Anyone want to kick this around?


          You'll end up with a multihull ;-)

          Ron
          Kismet 31 "Big Bird" (trimaran, building a cat)


          > YIBB,
          >
          > David Ryan
          > Minister of Information and Culture
          > Crumbling Empire Productions
          > (212) 247-0296
        • Giuseppe 'Pippo' Bianco
          David, you may want to read this nice article by Bruce Kirby http://www.coastalcruising.com/shallow.htm Very instructive! Best, Pippo david ryan
          Message 4 of 12 , Feb 1, 2000
            David,
            you may want to read this nice article by Bruce Kirby

            http://www.coastalcruising.com/shallow.htm

            Very instructive!
            Best, Pippo

            david ryan <davi-@...> wrote:
            original article:http://www.egroups.com/group/bolger/?start=2150
            > FBBB --
            >
            > I've been thinking a lot about stability and recovery, and studying
            > BWAOM very hard, especially the AS29 and LooseMoose. I think I'm
            > finally starting to get the shallow draft/high freeboard concept.
            >
            > Having spent my whole life sailing dingies, I have always equated
            > stability with hiking over the side, and maybe a weighed
            > centerboard. Recovery meant standing on the centerboard and prying
            > the thing back to upright. In a larger boat, this seemed to
            > *obviously* indicate the necessity of deep keels and heavy ballast.
            >
            > The AS29 and LM (if I understand correctly,) seem to prove otherwise,
            > and I am very intrigued.
            >
            > I've spent the weekend imaging a crusing sharpie that takes the
            > concept to extremes -- a very long, very slender craft sporting a low
            > sail plan and high freeboard: sort of like an extrastretched
            > tarantula (minus the keel) with a multi-mast sail plan and high
            > topsides. At what point is the beam to freeboard ratio optimized?
            >
            > Why this? The more I read, the more beaminess seems like a liability.
            > I'm beginning to suspect boat are made wide so as to make them easy
            > to sell, not easy to sail. I can't help but wonder what you end up
            > with if you design for maximum, rather than minimum waterline.
            >
            > Anyone want to kick this around?
            >
            > YIBB,
            >
            > David Ryan
            > Minister of Information and Culture
            > Crumbling Empire Productions
            > (212) 247-0296
          • David Ryan
            ... very stable right side up, very stable upside down. David Ryan Minister of Information and Culture Crumbling Empire Productions (212) 247-0296
            Message 5 of 12 , Feb 1, 2000
              >
              >
              >
              > You'll end up with a multihull ;-)
              >
              >Ron
              >Kismet 31 "Big Bird" (trimaran, building a cat)

              very stable right side up, very stable upside down.

              David Ryan
              Minister of Information and Culture
              Crumbling Empire Productions
              (212) 247-0296
            • Peter Vanderwaart
              David, Moderation in all things. Note that despite its boxy shape, the AS-29 is petty close to ordinary beam and weight for its length. The overall beam is
              Message 6 of 12 , Feb 1, 2000
                David,

                Moderation in all things. Note that despite its boxy shape, the AS-29
                is petty close to ordinary beam and weight for its length. The overall
                beam is perhaps less than average (due to having no flare), but the
                waterline beam is in the ordinary range.

                I think of these sharpies as being sort of like a banana, floating
                'convex down.' The rocker, which has virtues Mr. Bolger talks about
                with respect to flow, works with respect to stability by giving the
                boat a low belly, in which to put some ballast, and high ends. In a
                knockdown, the high ends move the center of buoyancey away from the
                ballast, giving a high righting moment (i.e. high reserve stability).
                However, this sort of stability does not give much sail carrying power
                at small angles of heel.

                The sail carrying power comes from hull sections with a lot of form
                stability, i.e. the box cross section, which depends on having adequate
                beam.

                If you take a small boat, and simply build it longer with the same
                beam, the resulting hull can carry more sail area in proportion to its
                length, but it can not carry it higher. As the boat gets longer and
                longer, the rig must stay the same height. As you go from one mast to
                two or three masts (remember Rondo II?), the aerodynamic effeciency
                suffers.

                That's my view, anyway.

                Peter

                >
                > I've been thinking a lot about stability and recovery, and studying
                > BWAOM very hard, especially the AS29 and LooseMoose. I think I'm
                > finally starting to get the shallow draft/high freeboard concept.
                >
              • ed haile
                David, Another aspect of all this, namely high freeboard. I had long objected to high sided boats as being such for the sake of too much downstairs at the
                Message 7 of 12 , Feb 1, 2000
                  David,

                  Another aspect of all this, namely high freeboard. I had long objected
                  to high sided boats as being such for the sake of too much "downstairs"
                  at the cost of excessive windage topside. A look at the oldtime
                  galleons and it's obvious they were exclusively downwind sailers. But
                  then something struck me in the Bolger boats. Look at the X-section of
                  a box boat. It's just about square. That means that windage (despite
                  the high sides) does not substantially increase or diminish with heel.
                  What's more, a square section (vertical sides) becomes more streamlined
                  when it heels (angled side facing the wind). Now look at your standard
                  dinghy, fin keel yacht. On an even keel most of them are very low. But
                  when they heel they throw up that ole weather rail and effectively have
                  the same windage as one of your box boats, if not more, and, since you
                  can see underneath, are much less streamlined.

                  Ever notice how in yacht photos you almost never see a picture of a
                  heeling yacht taken from windward.

                  Hull windage is an advantage downwind, precisely where standard brands
                  have the least, riding on an even keel. Windage is a disadvantage
                  upwind, precisely where standard brands develop it when they heel. So,
                  I became convinced that high freeboard was not a bad idea from a
                  windage standpoint, and from there to Bolger's statement that shallow
                  draft requires high freeboard.

                  To say nothing of rigging windage.

                  I am not yacht designer, and I admit in my lifetime on the water in
                  boats I have learned next to nothing. The above simply reasons from
                  facts & lines on paper. On the other hand, my Martha Jane pretty much
                  bears it all out.

                  Ed Haile
                • peter lenihan
                  Hello Ed, I never quite saw it that way but it sure does make a whole lot of sense,thanks!Now I have a wonderful arguement to give to all of my infidel friends
                  Message 8 of 12 , Feb 1, 2000
                    Hello Ed,
                    I never quite saw it that way but it sure does make a whole lot of sense,thanks!Now I have a wonderful arguement to give to all of my infidel friends without having to take them out for a sail on my Micro.
                    Despite the high sides of my Micro,I have never felt blown sideways since that lovely long keel just keeps on biting and biting long after the centerboarders and finkeelers have blown out of range!
                    Regards
                    Peter Lenihan


                    --- ed haile <bolger@egroups.com> wrote:
                    >David,
                    >
                    >Another aspect of all this, namely high freeboard. I had long objected
                    >to high sided boats as being such for the sake of too much "downstairs"
                    >at the cost of excessive windage topside. A look at the oldtime
                    >galleons and it's obvious they were exclusively downwind sailers. But
                    >then something struck me in the Bolger boats. Look at the X-section of
                    >a box boat. It's just about square. That means that windage (despite
                    >the high sides) does not substantially increase or diminish with heel.
                    >What's more, a square section (vertical sides) becomes more streamlined
                    >when it heels (angled side facing the wind). Now look at your standard
                    >dinghy, fin keel yacht. On an even keel most of them are very low. But
                    >when they heel they throw up that ole weather rail and effectively have
                    >the same windage as one of your box boats, if not more, and, since you
                    >can see underneath, are much less streamlined.
                    >
                    >Ever notice how in yacht photos you almost never see a picture of a
                    >heeling yacht taken from windward.
                    >
                    >Hull windage is an advantage downwind, precisely where standard brands
                    >have the least, riding on an even keel. Windage is a disadvantage
                    >upwind, precisely where standard brands develop it when they heel. So,
                    >I became convinced that high freeboard was not a bad idea from a
                    >windage standpoint, and from there to Bolger's statement that shallow
                    >draft requires high freeboard.
                    >
                    >To say nothing of rigging windage.
                    >
                    >I am not yacht designer, and I admit in my lifetime on the water in
                    >boats I have learned next to nothing. The above simply reasons from
                    >facts & lines on paper. On the other hand, my Martha Jane pretty much
                    >bears it all out.
                    >
                    >Ed Haile
                    >
                    >
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                  • David Ryan
                    FBBB -- I m glad I asked. My understanding continues to grow. A couple of thoughts/questions: 1) As I said before, I am convinced that *most* boats are
                    Message 9 of 12 , Feb 1, 2000
                      FBBB --

                      I'm glad I asked. My understanding continues to grow.

                      A couple of thoughts/questions:

                      1) As I said before, I am convinced that *most* boats are designed
                      with salability, not sailabilitly as their primary design
                      consideration. I think what has impressed my most about BWAOM is that
                      PCB is willing to realistically consider the way a boat will actually
                      be used. His comment about LM spending more time in port than in
                      ocean crossing, and then the resulting design really spoke to me. On
                      the other hand, since most boats spend most of their time tied up,
                      maybe a imitation offshore racer sponsors (that you don't actually
                      sail) sponsors more satisfying fantasies than a big Bolger box (that
                      you don't actually sail.) People sure get a big kick out of driving
                      SUVs will never see a dirt trail.

                      2) Tacking: Given similiar waterlines/rocker, is a narrower boat
                      harder to tack? Or is it simply that longer boats are harder to turn?
                      And besides, how often do you tack your LM on a trip from France to
                      Jamaica?

                      3) Multi-masts/Aero efficiency. As I understand it, multiple masts
                      are an answer to the practical limits of mast height, i.e. clippers
                      couldn't got as high as they wanted, so they went wide. Is this a
                      correct understanding? If it isn't, what is correct. If it is, where
                      are the practical lower limits (of hull size) of many small masts vs.
                      one big one?

                      What I am envisioning is a very long, very lean cruiser. She'd have
                      less sail, less beam, and more waterline. Doesn't tack very well? Who
                      cares, I'm on a beam reach for the next 1500 miles! No deep heavy
                      keel? If I can't get the nose into the wind and a sea anchor out,
                      I'll ride out the blow on my side (like Kerby's timber carrying
                      schooner,) confident my topsides will keep my from going any further.

                      Has Bolger or anyone else designed such a beast? If so, what are her
                      strengths? faults?

                      YIBB,


                      David Ryan
                      Minister of Information and Culture
                      Crumbling Empire Productions
                      (212) 247-0296
                    • ed haile
                      ... I think the issue here is maneuverability, something you don t give up lightly. ... The limit is sail size vs crew. Not mast height. Clippers had masts
                      Message 10 of 12 , Feb 1, 2000
                        > 2) Tacking: how often do you tack your LM on a trip from France to
                        > Jamaica?

                        I think the issue here is maneuverability, something you don't give up
                        lightly.

                        >
                        > 3) Multi-masts/Aero efficiency. As I understand it, multiple masts
                        > are an answer to the practical limits of mast height, i.e. clippers
                        > couldn't got as high as they wanted, so they went wide. Is this a
                        > correct understanding? If it isn't, what is correct. If it is, where
                        > are the practical lower limits (of hull size) of many small masts vs.
                        > one big one?

                        The limit is sail size vs crew. Not mast height. Clippers had masts
                        plenty high. But compare them to what went before and you see much
                        taller masts together with much smaller sails. They furled more than
                        they reefed and some prefer that on our-size boats. I think the Jochems
                        schooner has a lot of sails for an under-25 footer. Some might think
                        the main on a Loose Moose is a monster.

                        >
                        > What I am envisioning is a very long, very lean cruiser. She'd have
                        > less sail, less beam, and more waterline. Doesn't tack very well? Who
                        > cares, I'm on a beam reach for the next 1500 miles! No deep heavy
                        > keel? If I can't get the nose into the wind and a sea anchor out,
                        > I'll ride out the blow on my side (like Kerby's timber carrying
                        > schooner,) confident my topsides will keep my from going any further.

                        You might consider comfort important too, after a couple of blows. But
                        maneuverability.

                        >
                        > Has Bolger or anyone else designed such a beast? If so, what are her
                        > strengths? faults?
                        >
                        > YIBB,

                        The very question I put to PCB years ago: how about a long low-rig
                        sailing canoe? He referred me to the folding schooner. If he has
                        designed a proa since then, he might now mention that.

                        > David Ryan
                        > Minister of Information and Culture
                        > Crumbling Empire Productions
                        > (212) 247-0296
                      • Wmrpage@aol.com
                        How about this concept? Sail power is only required for those long hauls from Bermuda to the Azores, Canaries to Carribean - all down-hill sailing. Why use a
                        Message 11 of 12 , Feb 3, 2000
                          How about this concept? Sail power is only required for those long hauls from
                          Bermuda to the Azores, Canaries to Carribean - all down-hill sailing. Why use
                          a conventional rig, requiring a substantial righting moment (ballast or beam
                          = expense), if there was an alternative? My thought is of a reasonably long,
                          narrow, lightly balanced "box" suitable for low-powered internal combustion
                          engine operation in coastal waters, inland waters and canals, just
                          sufficiently ballasted for self-righting, with hatches amidship, etc. for
                          off-shore survivability. For the ocean crossings, one would use some form of
                          traction kites. Thrust from the kite could be taken at the rail by snatch
                          blocks. ( very low c.e. = low stability requirement for thrust developed).
                          Sail area ( I get the impression that projecting adequate non-chafing
                          downwind sail area in the Trades can be a problem with conventional boats)
                          would be independent of mast dimensions (low windage, low cost, low clearance
                          in canals). My perusal of traction kiting websites (e.g.
                          DaveCulpSpeedSailing) hasn't done much to dispel my ignorance of how such
                          kites are deployed and managed, but it does seem to me that they could
                          develop as much power as one could desire on courses up to at least a broad
                          reach with minimal heeling force. A buttoned-up hull of "Tennessee" or
                          "Wyoming" type dimensions (provided with some appendage to provide a suitable
                          CLR) might be one hell of a downwind sled.

                          Bill Page in the land of HARD water (MN)
                        • tjfatchen@ace.net.au
                          BO Another aspect of all this, namely high freeboard. I had long objected BO to high sided boats as being such for the sake of too much downstairs BO at the
                          Message 12 of 12 , Mar 11, 2000
                            BO>Another aspect of all this, namely high freeboard. I had long objected
                            BO>to high sided boats as being such for the sake of too much "downstairs"
                            BO>at the cost of excessive windage topside.
                            <snip>
                            BO>I became convinced that high freeboard was not a bad idea from a
                            BO>windage standpoint, and from there to Bolger's statement that shallow
                            BO>draft requires high freeboard.

                            BO>Ed Haile

                            I was originally alarmed at the windage possibilities of the AS29 hull,
                            particularly given the necessity to get out of tight and narrow marinas
                            (and back in) at dead slow speeds with vicious crosswinds. We did have
                            windage problems, in particular the bow falling off, but all to do with
                            the windage of the mainmast (which is quite respectable). The hull
                            itself, with boards down, is close to neutral.

                            Now, if they'd allow us to sail in and out of marina, we wouldnt have
                            any trouble at all....

                            Tim & Lady Kate
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