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Re: [bolger] Water Ballasted Chebacco

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  • eheins@corlink.com
    As a Chebacco owner, I think that there are some interesting points you ve made, however, IMHO, changing the hull geometry is beyond where I would go and still
    Message 1 of 26 , Jan 8, 2009
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      As a Chebacco owner, I think that there are some interesting points you've
      made, however, IMHO, changing the hull geometry is beyond where I would go
      and still consider the boat a Chebacco. One of the Chebacco's endearing
      points is it's ability to behave like a big dinghy, but stiffen up once
      the chine goes under. I'd be surprised if a round bilge, water ballasted
      configuration would improve on those characteristics. On the negative
      side, it would make the boat probably more difficult to trailer given that
      the flat bottom provides a stable platform to support in transit, and
      I've trailered Boudicea thousands of miles without a worry. I won't get
      into the ongoing controversy about water ballast in general, however I
      agree with the folks that discount the value, given that while the water
      ballast is submerged, it's virtually neutral bouyant although it adds some
      difference between the positive bouyancy of an air filled bilge. If it
      were me, I'd continue looking for a current design that had more of the
      characteristics you want, as my personal experience tends to be somewhat
      like Finagle's Law in that anything I try to make better usually results
      in something worse.




      > Greetings,
      >
      > I could not find the images in your link. It seems to me that water
      > ballast, being neutral buoyant at best, has no appreciable effect until it
      > is raised above the waterline. I will admit, however, that it has been
      > several years since I took a class in ship stability.
      >
      > V/R
      > Chris
      >
      >
      >
      > mcdennyw wrote:
      >> Righting moment at 20 degree heel increases from 1040 to 1440 ft-lbs, at
      >> 40 degrees from
      >> 1270 to 2520 ft-lbs. To put these numbers in perspective, at 20
      >> degrees I create a righting moment of 390 ft-lbs sitting on the
      >> windward seat; 320 ft-lbs at 40 degrees. So the water ballast is like
      >> having 4 extra people sitting to windward when it's getting hairy.
      >>
      >>
      >
      > ------------------------------------
      >
      > Bolger rules!!!
      > - NO "GO AWAY SPAMMER!" posts!!! Please!
      > - no cursing, flaming, trolling, spamming, respamming, 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
      >
      >
      >
      >
      > --
      > This message has been scanned for viruses and
      > dangerous content by MailScanner, and is
      > believed to be clean.
      >
      >
    • mcdennyw
      In casting about for a sail boat that two (geezerish) people could weekend on and I could tow comfortable behind my RAV4 (like to stay below 2000# incl
      Message 2 of 26 , Jan 8, 2009
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        In casting about for a sail boat that two (geezerish) people could
        weekend on and I could tow comfortable behind my RAV4 (like to stay
        below 2000# incl trailer, lighter is better) I first spent a lot of
        Freeship time massaging Garden's "Eel" to make it bigger but finally
        decided I ought to find a larger, simpler (no boomkin or bowsprit)
        boat. Most designs are ballasted, making them too heavy for me to
        trailer. Irens' Romilly is a beauty but has an 1150# lead shoe

        Bolger's Chebacco fits my parameters pretty well and comes in 19.5'
        and 25' glued lapstrake versions. No ballast so the weight on the
        trailer for the 19'er is about 1100#, about 1350# for the 25. (all
        according to Freeship). There is a nice Chebacco website with lots of
        good pics to keep me surfing the net instead of shoveling snow.

        Since I can't leave well enough alone, I'd like to improve two things-
        1) Get rid of the flat bottom. It must be a carry over from the
        sheet ply version. Building lapstrake, it wouldn't be much extra work
        to carry the strakes down to the keel. This would improve the looks
        IMHO and avoid the chance for ripples to slap against the bottom at
        anchor. 2) Add some ballast to stiffen the boat (geezerish, remember -
        no hiking straps).

        Hey - how about filling the extra volume created by the round instead
        of flat bottom with water? Now the boat will float on its designed
        waterline, no extra weight on trailer and considerably stiffer. Turns
        out there is room for 500# of water under the sole. Wetted surface
        only goes up 2%

        Using water ballast adds weight and righting moment without making
        the boat more "sinkable" or more difficult to trailer. It does add 3
        inches to board up draft but I can live with that. Righting moment at
        20 degree heel increases from 1040 to 1440 ft-lbs, at 40 degrees from
        1270 to 2520 ft-lbs. To put these numbers in perspective, at 20
        degrees I create a righting moment of 390 ft-lbs sitting on the
        windward seat; 320 ft-lbs at 40 degrees. So the water ballast is like
        having 4 extra people sitting to windward when it's getting hairy.

        Negatives: the exra 500# will reduce the speed by about 10% unless
        sail area is increased and there is some added construction
        complexity.


        What do you think? This seems like such an obviously good idea I must
        be missing something. I'd be especially interested in hearing from
        actual Chebacco owners

        This notion is also posted on the WoodenBoat Forum at
        http://www.woodenboat.com/forum/showthread.php?
        p=2060781&posted=1#post2060781


        There you can see Freeship renderings of the two hulls and the
        righting moment curves.
      • Christopher C. Wetherill
        Greetings, I could not find the images in your link. It seems to me that water ballast, being neutral buoyant at best, has no appreciable effect until it is
        Message 3 of 26 , Jan 8, 2009
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          Greetings,

          I could not find the images in your link. It seems to me that water ballast, being neutral buoyant at best, has no appreciable effect until it is raised above the waterline. I will admit, however, that it has been several years since I took a class in ship stability.

          V/R
          Chris



          mcdennyw wrote:
          > Righting moment at 20 degree heel increases from 1040 to 1440 ft-lbs, at 40 degrees from
          > 1270 to 2520 ft-lbs. To put these numbers in perspective, at 20
          > degrees I create a righting moment of 390 ft-lbs sitting on the
          > windward seat; 320 ft-lbs at 40 degrees. So the water ballast is like
          > having 4 extra people sitting to windward when it's getting hairy.
          >
          >
        • Bruce Hallman
          ... Water ballast also gives a boat increased inertia, at all times, which can be a good thing for several reasons.
          Message 4 of 26 , Jan 8, 2009
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            > water ballast, being neutral buoyant at best, has no appreciable effect until it is raised
            > above the waterline.

            Water ballast also gives a boat increased inertia, at all times, which
            can be a good thing for several reasons.
          • mcdennyw
            Glad to hear from an actual owner so quickly. Thanks. Which variant do you have? Sheet ply? Lapstrake? Any ballast? Weighted C board? Do you hear ripples
            Message 5 of 26 , Jan 8, 2009
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              Glad to hear from an actual owner so quickly. Thanks.

              Which variant do you have? Sheet ply? Lapstrake? Any ballast?
              Weighted C'board?

              Do you hear ripples slapping against the bottom at anchor?

              Does the boat easily sail through the eye of the wind when you tack?

              Ever had a capsize? Near capsize? Scary ride?

              I appreciate your first hand info.

              Denny Wolfe
              www.wolfEboats.com


              More comments below:

              --- In bolger@yahoogroups.com, eheins@... wrote:
              >
              > As a Chebacco owner, I think that there are some interesting points
              you've
              > made, however, IMHO, changing the hull geometry is beyond where I
              would go
              > and still consider the boat a Chebacco. One of the Chebacco's
              endearing
              > points is it's ability to behave like a big dinghy, but stiffen up
              once
              > the chine goes under. I'd be surprised if a round bilge, water
              ballasted
              > configuration would improve on those characteristics.

              The righting moment of the water ballasted boat is the same as no
              ballast flat bottom at low angles of heel. The "above the waterline"
              shape is the same in both cases so the form stability is the same
              too. The water ballast begins to make itself felt at angles above
              about 15 degrees and gets rapidly more significant as more of the
              ballast is raised above the water line.


              > it would make the boat probably more difficult to trailer given
              that
              > the flat bottom provides a stable platform to support in transit,
              and
              > I've trailered Boudicea thousands of miles without a worry.

              I agree the trailer bunks would have to be a bit more complex to
              accomodate the round bottom hull.

              I won't get
              > into the ongoing controversy about water ballast in general,
              however I
              > agree with the folks that discount the value, given that while the
              water
              > ballast is submerged, it's virtually neutral bouyant although it
              adds some
              > difference between the positive bouyancy of an air filled bilge.

              I agree, too, that the water ballast can't make any righting moment
              difference unitl it begins to go above the water surface. It doesn't
              take much of a heeling angle to do that, however. Its weight
              increases forward momentum so making the boat more sure through
              stays. It has a negative effect on speed - about 10% at 5 kts - but
              sail area could be increased proportionally to restore the speed.

              If it
              > were me, I'd continue looking for a current design that had more of
              the
              > characteristics you want, as my personal experience tends to be
              somewhat
              > like Finagle's Law in that anything I try to make better usually
              results
              > in something worse.

              I hear you there!!
              >
              >
            • mcdennyw
              Chris, You need both lines of the link - the yahoo text editor cut it in two. Alternatively look in the designs and plans section of the WoodenBoat Forum
              Message 6 of 26 , Jan 8, 2009
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                Chris, You need both lines of the link - the yahoo text editor cut
                it in two. Alternatively look in the "designs and plans" section of
                the WoodenBoat Forum for the "Water Ballast Chebacco topic"

                I sort of agree with the notion that the water doesn't have a
                righting moment until it goes above the actual water line because we
                are comparing a flat bottom to a deeper round bottom. Its like the
                water ballast is on the outside of the flat bottom.

                The round bottom hull would be less stable than the flat without the
                water ballast.

                --- In bolger@yahoogroups.com, "Christopher C. Wetherill"
                <wetherillc@...> wrote:
                >
                > Greetings,
                >
                > I could not find the images in your link. It seems to me that
                water ballast, being neutral buoyant at best, has no appreciable
                effect until it is raised above the waterline. I will admit,
                however, that it has been several years since I took a class in ship
                stability.
                >
                > V/R
                > Chris
                >
                >
                >
              • eheins@corlink.com
                Denny, I have a very stock sheet ply version. No ballast. The CB is only weighted to the basic spec to facilitate lowering and staying down. I do not
                Message 7 of 26 , Jan 8, 2009
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                  Denny,
                  I have a very stock sheet ply version. No ballast. The CB is
                  only weighted to the basic spec to facilitate lowering and staying
                  down. I do not necessarily get significant wave noise when at
                  anchor, but have never spent the night on board. I day sail it
                  mostly. Never capsized, but I'm a conservative sailor I've only
                  ever heard of one knockdown and that was in Penobsoct Bay as I
                  recall, but I could have that wrong. A scary ride is relative. As
                  I said, it's a big dinghy and needs to be handled with a sensitive
                  hand on the main sheet. At least that's how I sail her. The
                  rudder is surprisingly effective given the size and I tend to sail
                  it through the wind. Being unballasted I try to think that it's a
                  big laser and use the main to help tack. The mizzen at best is a
                  steadying sail, and in many wind conditions more aesthetic than
                  functional.
                  Be sure that it's cut dead flat by the way. I hear with any camber at all
                  it induces some negative helm characteristics. I wouldn't know about that
                  since I had Bohndell cut my sails to Bolger's specs and they are
                  excellent.

                  Hope this helps,

                  Ed




                  > Glad to hear from an actual owner so quickly. Thanks.
                  >
                  > Which variant do you have? Sheet ply? Lapstrake? Any ballast?
                  > Weighted C'board?
                  >
                  > Do you hear ripples slapping against the bottom at anchor?
                  >
                  > Does the boat easily sail through the eye of the wind when you tack?
                  >
                  > Ever had a capsize? Near capsize? Scary ride?
                  >
                  > I appreciate your first hand info.
                  >
                  > Denny Wolfe
                  > www.wolfEboats.com
                  >
                  >
                  > More comments below:
                  >
                  > --- In bolger@yahoogroups.com, eheins@... wrote:
                  >>
                  >> As a Chebacco owner, I think that there are some interesting points
                  > you've
                  >> made, however, IMHO, changing the hull geometry is beyond where I
                  > would go
                  >> and still consider the boat a Chebacco. One of the Chebacco's
                  > endearing
                  >> points is it's ability to behave like a big dinghy, but stiffen up
                  > once
                  >> the chine goes under. I'd be surprised if a round bilge, water
                  > ballasted
                  >> configuration would improve on those characteristics.
                  >
                  > The righting moment of the water ballasted boat is the same as no
                  > ballast flat bottom at low angles of heel. The "above the waterline"
                  > shape is the same in both cases so the form stability is the same
                  > too. The water ballast begins to make itself felt at angles above
                  > about 15 degrees and gets rapidly more significant as more of the
                  > ballast is raised above the water line.
                  >
                  >
                  >> it would make the boat probably more difficult to trailer given
                  > that
                  >> the flat bottom provides a stable platform to support in transit,
                  > and
                  >> I've trailered Boudicea thousands of miles without a worry.
                  >
                  > I agree the trailer bunks would have to be a bit more complex to
                  > accomodate the round bottom hull.
                  >
                  > I won't get
                  >> into the ongoing controversy about water ballast in general,
                  > however I
                  >> agree with the folks that discount the value, given that while the
                  > water
                  >> ballast is submerged, it's virtually neutral bouyant although it
                  > adds some
                  >> difference between the positive bouyancy of an air filled bilge.
                  >
                  > I agree, too, that the water ballast can't make any righting moment
                  > difference unitl it begins to go above the water surface. It doesn't
                  > take much of a heeling angle to do that, however. Its weight
                  > increases forward momentum so making the boat more sure through
                  > stays. It has a negative effect on speed - about 10% at 5 kts - but
                  > sail area could be increased proportionally to restore the speed.
                  >
                  > If it
                  >> were me, I'd continue looking for a current design that had more of
                  > the
                  >> characteristics you want, as my personal experience tends to be
                  > somewhat
                  >> like Finagle's Law in that anything I try to make better usually
                  > results
                  >> in something worse.
                  >
                  > I hear you there!!
                  >>
                  >>
                  >
                  >
                  > ------------------------------------
                  >
                  > Bolger rules!!!
                  > - NO "GO AWAY SPAMMER!" posts!!! Please!
                  > - no cursing, flaming, trolling, spamming, respamming, 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
                  >
                  >
                  >
                  >
                  > --
                  > This message has been scanned for viruses and
                  > dangerous content by MailScanner, and is
                  > believed to be clean.
                  >
                  >
                • Christopher C. Wetherill
                  Denny, Here s what I did: 1 reply to e-mail - opens editable copy of message 2 delete line feed in link 3 copy and paste link to address line of either Firefox
                  Message 8 of 26 , Jan 8, 2009
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                    Denny,

                    Here's what I did:

                    1 reply to e-mail - opens editable copy of message
                    2 delete line feed in link
                    3 copy and paste link to address line of either Firefox or Internet Exploder

                    In Firefox the links do not appear, only the captions. In IE, they show
                    up as closed images. I tried again while writing this and found I could
                    open them by right click selecting properties for each closed image and
                    pasting the urls in seperate tabs. Strange. Could be the result of my
                    firewall settings.

                    V/R
                    Chris

                    mcdennyw wrote:
                    > Chris, You need both lines of the link - the yahoo text editor cut
                    > it in two. Alternatively look in the "designs and plans" section of
                    > the WoodenBoat Forum for the "Water Ballast Chebacco topic"
                    >
                    >


                    [Non-text portions of this message have been removed]
                  • mcdennyw
                    Thanks, Ed. I went to Chebacco.com and looked at your pictures - very nice job! I was at MASCF in 2007 with my electric launch. What a great time. Another
                    Message 9 of 26 , Jan 8, 2009
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                      Thanks, Ed.

                      I went to Chebacco.com and looked at your pictures - very nice job!

                      I was at MASCF in 2007 with my electric launch. What a great time.

                      Another question: Have you ever weighed your boat?

                      Denny

                      --- In bolger@yahoogroups.com, eheins@... wrote:
                      >
                      > Denny,
                      > I have a very stock sheet ply version. No ballast. The CB is
                      > only weighted to the basic spec to facilitate lowering and staying
                    • Chris Feller
                      It sounds like you have many good ideas. I would not change the hull shape. That would make it a different boat than the designer had in mind. One benefit
                      Message 10 of 26 , Jan 8, 2009
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                        It sounds like you have many good ideas. I would not change the hull
                        shape. That would make it a different boat than the designer had in
                        mind. One benefit you would be loosing is the ability to beach the
                        boat on the flat bottom as well. Also on construction the flat bottom
                        with lapstrake sides is a traditional style. In John Gardner's Dory
                        Book he describes this construction on the Semi-Dory. Below is a link
                        to an article on one.

                        http://www.duckworksmagazine.com/03/r/articles/affair/index.htm

                        On ballast I believe water ballast is an effective way of adding
                        ballast. I know there is much controversy over it but it has been
                        used effectively on many boats. Although I don't know that I would
                        use it on this boat since it was designed for no ballast. For the
                        answer to this question I would look to those who have used a
                        Chebacco. Perhaps someone has done some testing with ballast.

                        Chris Feller
                        --- In bolger@yahoogroups.com, "mcdennyw" <dwolfe@...> wrote:
                        >
                        > In casting about for a sail boat that two (geezerish) people could
                        > weekend on and I could tow comfortable behind my RAV4 (like to stay
                        > below 2000# incl trailer, lighter is better) I first spent a lot of
                        > Freeship time massaging Garden's "Eel" to make it bigger but finally
                        > decided I ought to find a larger, simpler (no boomkin or bowsprit)
                        > boat. Most designs are ballasted, making them too heavy for me to
                        > trailer. Irens' Romilly is a beauty but has an 1150# lead shoe
                        >
                        > Bolger's Chebacco fits my parameters pretty well and comes in 19.5'
                        > and 25' glued lapstrake versions. No ballast so the weight on the
                        > trailer for the 19'er is about 1100#, about 1350# for the 25. (all
                        > according to Freeship). There is a nice Chebacco website with lots of
                        > good pics to keep me surfing the net instead of shoveling snow.
                        >
                        > Since I can't leave well enough alone, I'd like to improve two things-
                        > 1) Get rid of the flat bottom. It must be a carry over from the
                        > sheet ply version. Building lapstrake, it wouldn't be much extra work
                        > to carry the strakes down to the keel. This would improve the looks
                        > IMHO and avoid the chance for ripples to slap against the bottom at
                        > anchor. 2) Add some ballast to stiffen the boat (geezerish, remember -
                        > no hiking straps).
                        >
                        > Hey - how about filling the extra volume created by the round instead
                        > of flat bottom with water? Now the boat will float on its designed
                        > waterline, no extra weight on trailer and considerably stiffer. Turns
                        > out there is room for 500# of water under the sole. Wetted surface
                        > only goes up 2%
                        >
                        > Using water ballast adds weight and righting moment without making
                        > the boat more "sinkable" or more difficult to trailer. It does add 3
                        > inches to board up draft but I can live with that. Righting moment at
                        > 20 degree heel increases from 1040 to 1440 ft-lbs, at 40 degrees from
                        > 1270 to 2520 ft-lbs. To put these numbers in perspective, at 20
                        > degrees I create a righting moment of 390 ft-lbs sitting on the
                        > windward seat; 320 ft-lbs at 40 degrees. So the water ballast is like
                        > having 4 extra people sitting to windward when it's getting hairy.
                        >
                        > Negatives: the exra 500# will reduce the speed by about 10% unless
                        > sail area is increased and there is some added construction
                        > complexity.
                        >
                        >
                        > What do you think? This seems like such an obviously good idea I must
                        > be missing something. I'd be especially interested in hearing from
                        > actual Chebacco owners
                        >
                        > This notion is also posted on the WoodenBoat Forum at
                        > http://www.woodenboat.com/forum/showthread.php?
                        > p=2060781&posted=1#post2060781
                        >
                        >
                        > There you can see Freeship renderings of the two hulls and the
                        > righting moment curves.
                        >
                      • Jack&Lois
                        You are obviously well informed and educated re.righting moment, hull speed, and other mystical aspects of boat design. I only want to say that I spent a
                        Message 11 of 26 , Jan 8, 2009
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                          You are obviously well informed and educated re.righting moment, hull speed,
                          and other mystical aspects of boat design. I only want to say that I spent a
                          delightful afternoon last summer with Harold Payson on his back porch last
                          summer discussing Bolger designs. One comment from Payson stays with me.
                          "Bolger has an uncanny understanding of what the underwater shape of a boat
                          should be." That remark alone is enough to prevent me mucking about with
                          anything below the waterline on any Bolger design. I have taken some
                          liberties with the top sides of several of his designs. None have proved
                          disastrous. But have I really improved anything? Who knows? Just thought I
                          should mention this. Good luck.



                          jeb, suspecting global warming is a very silly conspiracy theory, on the
                          frozen shores of the Bay of Fundy.



                          [Non-text portions of this message have been removed]
                        • Christopher C. Wetherill
                          Chris, There is a keel. V/R Chris
                          Message 12 of 26 , Jan 8, 2009
                          • 0 Attachment
                            Chris,

                            There is a keel.

                            V/R
                            Chris

                            Chris Feller wrote:
                            > One benefit you would be loosing is the ability to beach the
                            > boat on the flat bottom as well.
                            >
                          • Christopher C. Wetherill
                            Denny, I have had a chance to check Boats with an Open Mind. Drawing on page226 shows design displacement for plywood 19.5 Chebacco is 1740 lbs. Drawing on
                            Message 13 of 26 , Jan 8, 2009
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                              Denny,
                              I have had a chance to check Boats with an Open Mind. Drawing on
                              page226 shows design displacement for plywood 19.5' Chebacco is 1740
                              lbs. Drawing on page 232 shows 25' at 2300 lbs.

                              V/R
                              Chris

                              mcdennyw wrote:
                              > In casting about for a sail boat that two (geezerish) people could
                              > weekend on and I could tow comfortable behind my RAV4 (like to stay
                              > below 2000# incl trailer, lighter is better) I first spent a lot of
                              > Freeship time massaging Garden's "Eel" to make it bigger but finally
                              > decided I ought to find a larger, simpler (no boomkin or bowsprit)
                              > boat. Most designs are ballasted, making them too heavy for me to
                              > trailer. Irens' Romilly is a beauty but has an 1150# lead shoe
                              >
                              > Bolger's Chebacco fits my parameters pretty well and comes in 19.5'
                              > and 25' glued lapstrake versions. No ballast so the weight on the
                              > trailer for the 19'er is about 1100#, about 1350# for the 25. (all
                              > according to Freeship). There is a nice Chebacco website with lots of
                              > good pics to keep me surfing the net instead of shoveling snow.
                              >
                              > Since I can't leave well enough alone, I'd like to improve two things-
                              > 1) Get rid of the flat bottom. It must be a carry over from the
                              > sheet ply version. Building lapstrake, it wouldn't be much extra work
                              > to carry the strakes down to the keel. This would improve the looks
                              > IMHO and avoid the chance for ripples to slap against the bottom at
                              > anchor. 2) Add some ballast to stiffen the boat (geezerish, remember -
                              > no hiking straps).
                              >
                              > Hey - how about filling the extra volume created by the round instead
                              > of flat bottom with water? Now the boat will float on its designed
                              > waterline, no extra weight on trailer and considerably stiffer. Turns
                              > out there is room for 500# of water under the sole. Wetted surface
                              > only goes up 2%
                              >
                              > Using water ballast adds weight and righting moment without making
                              > the boat more "sinkable" or more difficult to trailer. It does add 3
                              > inches to board up draft but I can live with that. Righting moment at
                              > 20 degree heel increases from 1040 to 1440 ft-lbs, at 40 degrees from
                              > 1270 to 2520 ft-lbs. To put these numbers in perspective, at 20
                              > degrees I create a righting moment of 390 ft-lbs sitting on the
                              > windward seat; 320 ft-lbs at 40 degrees. So the water ballast is like
                              > having 4 extra people sitting to windward when it's getting hairy.
                              >
                              > Negatives: the exra 500# will reduce the speed by about 10% unless
                              > sail area is increased and there is some added construction
                              > complexity.
                              >
                              >
                              > What do you think? This seems like such an obviously good idea I must
                              > be missing something. I'd be especially interested in hearing from
                              > actual Chebacco owners
                              >
                              > This notion is also posted on the WoodenBoat Forum at
                              > http://www.woodenboat.com/forum/showthread.php?
                              > p=2060781&posted=1#post2060781
                              >
                              >
                              > There you can see Freeship renderings of the two hulls and the
                              > righting moment curves.
                              >
                              >
                              > ------------------------------------
                              >
                              > Bolger rules!!!
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                              > - 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
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                              >
                              >
                              >
                              >
                              >


                              [Non-text portions of this message have been removed]
                            • Christopher C. Wetherill
                              Denny, Please excuse the terse nature of my last post. I claim the lateness of the hour. I have since spent a little more time with BwaOM. Loaded
                              Message 14 of 26 , Jan 9, 2009
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                                Denny,

                                Please excuse the terse nature of my last post. I claim the lateness of
                                the hour. I have since spent a little more time with BwaOM. Loaded
                                displacements below are per Mr Bolger's drawings. There is a further
                                section in the book for a trailerable sharpie, based on Black Skimmer,
                                called Martha Jane. Per drawings on page 248 and 249, this boat is
                                designed for water ballast of 500 lbs seawater and loaded displacement
                                of 2350 lbs. In the text he states the dry weight at 1300 lbs. Since
                                he is talking about trailer sailing, I would presume he includes the
                                weight of the rig. This implies the weight of crew and gear is around
                                550 lbs. If this is a consistent value in his designs, one could infer
                                that the 19.5' Chebacco would weigh less than 1200 lbs and the 25' one
                                about 1750 lbs.

                                If you want a boat that will dry out standing up, I would look at MJ.
                                It's designed for water ballast and I doubt you will get more in 23.5'
                                at under 1500 lbs on the trailer.

                                V/R
                                Chris

                                Christopher C. Wetherill wrote:
                                > Denny,
                                > I have had a chance to check Boats with an Open Mind. Drawing on
                                > page226 shows design displacement for plywood 19.5' Chebacco is 1740
                                > lbs. Drawing on page 232 shows 25' at 2300 lbs.
                                >
                                > V/R
                                > Chris
                                >
                              • mcdennyw
                                Chris, the displacement figures refer to how much weight is required to sink the boat down to its designed waterline. This includes the weight of the boat
                                Message 15 of 26 , Jan 9, 2009
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                                  Chris, the displacement figures refer to how much weight is required to
                                  sink the boat down to its designed waterline. This includes the weight
                                  of the boat itself plus the weight of people and gear.

                                  On pg 229 Bolger says, referring to the 25'er, " The extra length adds
                                  several hundred pounds to the half ton weight of the 20'er". Here he
                                  is talking about the boat's weight, not displacement.

                                  My Freeship model indicates the weight of the empty 20' boat is 1100
                                  pounds and the 25 is a bit over 1400 lbs. 1100# is close enough to
                                  a "half ton" to suggest the model is reasonably accurate.

                                  I've towed a 1700# boat on a 600# trailer to Florida and back with the
                                  RAV4 (2007, V6 engine). It drove OK but the gas mileage really sucked -
                                  from its usual 24 down to 14 mpg.

                                  Denny

                                  --- In bolger@yahoogroups.com, "Christopher C. Wetherill"
                                  <wetherillc@...> wrote:
                                  >
                                  > Denny,
                                  > I have had a chance to check Boats with an Open Mind. Drawing on
                                  > page226 shows design displacement for plywood 19.5' Chebacco is 1740
                                  > lbs. Drawing on page 232 shows 25' at 2300 lbs.
                                  >
                                  > V/R
                                  > Chris
                                  >
                                • Christopher C. Wetherill
                                  Denny, You will see in my second post, that after spending a little more time thinking than spouting I came into agreement with your numbers. One question
                                  Message 16 of 26 , Jan 9, 2009
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                                    Denny,

                                    You will see in my second post, that after spending a little more time
                                    thinking than spouting I came into agreement with your numbers. One
                                    question though. Since the modification you propose changes the
                                    displacement, did you run an evaluation on the effect of simply fitting
                                    the water in the unmodified volume?

                                    V/R
                                    Chris


                                    mcdennyw wrote:
                                    > Chris, the displacement figures refer to how much weight is required to
                                    > sink the boat down to its designed waterline. This includes the weight
                                    > of the boat itself plus the weight of people and gear.
                                    >
                                    > On pg 229 Bolger says, referring to the 25'er, " The extra length adds
                                    > several hundred pounds to the half ton weight of the 20'er". Here he
                                    > is talking about the boat's weight, not displacement.
                                    >
                                    > My Freeship model indicates the weight of the empty 20' boat is 1100
                                    > pounds and the 25 is a bit over 1400 lbs. 1100# is close enough to
                                    > a "half ton" to suggest the model is reasonably accurate.
                                    >
                                    > I've towed a 1700# boat on a 600# trailer to Florida and back with the
                                    > RAV4 (2007, V6 engine). It drove OK but the gas mileage really sucked -
                                    > from its usual 24 down to 14 mpg.
                                    >
                                    > Denny
                                    >
                                    >
                                    >
                                  • Chris Feller
                                    Good point. I guess I should have looked at the plans before writing. Never mind about the beaching thing. Chris Feller
                                    Message 17 of 26 , Jan 9, 2009
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                                      Good point. I guess I should have looked at the plans before writing.
                                      Never mind about the beaching thing.

                                      Chris Feller
                                      --- In bolger@yahoogroups.com, "Christopher C. Wetherill"
                                      <wetherillc@...> wrote:
                                      >
                                      > Chris,
                                      >
                                      > There is a keel.
                                      >
                                      > V/R
                                      > Chris
                                      >
                                      > Chris Feller wrote:
                                      > > One benefit you would be loosing is the ability to beach the
                                      > > boat on the flat bottom as well.
                                      > >
                                      >
                                    • Mark Albanese
                                      ... Thanks to all who commented on this. I tried refaxing my inquiry. Good news! A reply came not 48 hours later, signed by Phil. The not so good news is that
                                      Message 18 of 26 , Jan 9, 2009
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                                        >>

                                        Thanks to all who commented on this.

                                        I tried refaxing my inquiry. Good news! A reply came not 48 hours
                                        later, signed by Phil.
                                        The not so good news is that Diamond Kayak plans, #615, are now $75.

                                        Mark
                                      • Jamie Orr
                                        Hi, Somone in this thread asked if anyone had ballasted a Chebacco. If you check the earliest Chebacco Newsletters, which are archived at www.chebacco.com,
                                        Message 19 of 26 , Jan 9, 2009
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                                          Hi,

                                          Somone in this thread asked if anyone had ballasted a Chebacco. If
                                          you check the earliest Chebacco Newsletters, which are archived at
                                          www.chebacco.com, you'll see there was a boat owned by Sister Krista
                                          with 300# of ballast. When sold the boat the new owner didn't waste
                                          much time before removing the ballast.

                                          I have an unballasted Chebacco and have never felt the need for
                                          ballast. My feeling is that PCB got it right, why screw it up?

                                          Jamie Orr
                                          S/V Wayward Lass

                                          --- In bolger@yahoogroups.com, "mcdennyw" <dwolfe@...> wrote:
                                          >
                                          > In casting about for a sail boat that two (geezerish) people could
                                          > weekend on and I could tow comfortable behind my RAV4 (like to stay
                                          > below 2000# incl trailer, lighter is better) I first spent a lot of
                                          > Freeship time massaging Garden's "Eel" to make it bigger but
                                          finally
                                          > decided I ought to find a larger, simpler (no boomkin or bowsprit)
                                          > boat. Most designs are ballasted, making them too heavy for me to
                                          > trailer. Irens' Romilly is a beauty but has an 1150# lead shoe
                                          >
                                          > Bolger's Chebacco fits my parameters pretty well and comes in 19.5'
                                          > and 25' glued lapstrake versions. No ballast so the weight on the
                                          > trailer for the 19'er is about 1100#, about 1350# for the 25. (all
                                          > according to Freeship). There is a nice Chebacco website with lots
                                          of
                                          > good pics to keep me surfing the net instead of shoveling snow.
                                          >
                                          > Since I can't leave well enough alone, I'd like to improve two
                                          things-
                                          > 1) Get rid of the flat bottom. It must be a carry over from the
                                          > sheet ply version. Building lapstrake, it wouldn't be much extra
                                          work
                                          > to carry the strakes down to the keel. This would improve the looks
                                          > IMHO and avoid the chance for ripples to slap against the bottom at
                                          > anchor. 2) Add some ballast to stiffen the boat (geezerish,
                                          remember -
                                          > no hiking straps).
                                          >
                                          > Hey - how about filling the extra volume created by the round
                                          instead
                                          > of flat bottom with water? Now the boat will float on its designed
                                          > waterline, no extra weight on trailer and considerably stiffer.
                                          Turns
                                          > out there is room for 500# of water under the sole. Wetted surface
                                          > only goes up 2%
                                          >
                                          > Using water ballast adds weight and righting moment without making
                                          > the boat more "sinkable" or more difficult to trailer. It does add
                                          3
                                          > inches to board up draft but I can live with that. Righting moment
                                          at
                                          > 20 degree heel increases from 1040 to 1440 ft-lbs, at 40 degrees
                                          from
                                          > 1270 to 2520 ft-lbs. To put these numbers in perspective, at 20
                                          > degrees I create a righting moment of 390 ft-lbs sitting on the
                                          > windward seat; 320 ft-lbs at 40 degrees. So the water ballast is
                                          like
                                          > having 4 extra people sitting to windward when it's getting hairy.
                                          >
                                          > Negatives: the exra 500# will reduce the speed by about 10% unless
                                          > sail area is increased and there is some added construction
                                          > complexity.
                                          >
                                          >
                                          > What do you think? This seems like such an obviously good idea I
                                          must
                                          > be missing something. I'd be especially interested in hearing from
                                          > actual Chebacco owners
                                          >
                                          > This notion is also posted on the WoodenBoat Forum at
                                          > http://www.woodenboat.com/forum/showthread.php?
                                          > p=2060781&posted=1#post2060781
                                          >
                                          >
                                          > There you can see Freeship renderings of the two hulls and the
                                          > righting moment curves.
                                          >
                                        • mcdennyw
                                          Someone suggested that I try the water balast calculation with the boat as-designed, that is without rounding off the bottom. After finding this post from a
                                          Message 20 of 26 , Jan 11, 2009
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                                            Someone suggested that I try the water balast calculation with the
                                            boat as-designed, that is without rounding off the bottom. After
                                            finding this post from a respected NA, Tad Roberts, on the Woodenboat
                                            forum:
                                            -------------------------------------
                                            Water ballast is useful and does work, but only in very specific
                                            circumstances. In the typical lead mine sailboat (and your physics
                                            experiments above) that Bob is referring to, it would be useless.

                                            Mr. Bolger, Hunter, and I believe Macgregor all use water ballast to
                                            good effect. These are all hulls that are shallow, wide bottomed (in
                                            Bolger's case rectangular), and lightweight. The water ballast is
                                            contained in tanks that are the full width of the boat, but not very
                                            high vertically. The rectangular or almost rectangular midsection
                                            means these boats rely on form stability at low heel angles. As the
                                            boat heels, the water ballast rises above the waterline very quickly,
                                            and becomes working ballast. The barge hull form runs out of form
                                            stability quickly, and this is were the ballast becomes effective.
                                            But only at fairly high heel angles, probably 20 degrees or more.
                                            Most of us aren't used to sailing at those high angles any more.

                                            It enables a hull of very light trailering weight to also be self
                                            righting (if she has either floation or a watertight cabin) from a
                                            complete knockdown. Water ballast will also smooth out motion and
                                            give a very light hull some momentum. In the case of the Macgregor it
                                            enables a useable (and reasonably safe) sailboat, to dump her ballast
                                            and plane off under outboard power. Another excellent feature is that
                                            if your water ballasted boat is knocked down and fills, she will not
                                            sink. Coupled with extremely shallow draft on launching, which can be
                                            very handy, it makes sense.

                                            As always, horse's for course's.

                                            All the best, Tad.
                                            -------------------------
                                            The Chebacco, as designed, is just the form Tad suggests would
                                            benefit from water ballast. I revised my Freeship model to put 500#
                                            of water ballast in the 19' flat bottom boat and...

                                            ta daa - it is much stiffer than my round bottom idea. At a 20
                                            degree angle of heel (sailing to windward in a fresh breeze, the flat
                                            bottom water ballasted boat has a righting moment of 1880 ft-lbs, 30%
                                            better than the round bottom boat and 80% more than the unballasted
                                            boat. Evan at 5 and 10 degrees the water ballasted boat has almost
                                            double the moment of the stock boat. The extra 500# causes the boat
                                            to sink down just 1.5" deeper.

                                            The ballast tank is essentially a false bottom parallel to the
                                            waterline and 5" deeep at its deepest point in the middle of the
                                            boat. Sounds like an even better idea than the original post.

                                            Denny Wolfe
                                          • Doug Pollard
                                            ... While your at it put a fifty gallon inflatable holding bladder inside the water ballast tank that will expand when waste is pumped in and collaps when it
                                            Message 21 of 26 , Jan 11, 2009
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                                              mcdennyw wrote:
                                              >
                                              > Someone suggested that I try the water balast calculation with the
                                              > boat as-designed, that is without rounding off the bottom. After
                                              > finding this post from a respected NA, Tad Roberts, on the Woodenboat
                                              > forum:
                                              > -------------------------------------
                                              > Water ballast is useful and does work, but only in very specific
                                              > circumstances. In the typical lead mine sailboat (and your physics
                                              > experiments above) that Bob is referring to, it would be useless.
                                              >
                                              > Mr. Bolger, Hunter, and I believe Macgregor all use water ballast to
                                              > good effect. These are all hulls that are shallow, wide bottomed (in
                                              > Bolger's case rectangular), and lightweight. The water ballast is
                                              > contained in tanks that are the full width of the boat, but not very
                                              > high vertically. The rectangular or almost rectangular midsection
                                              > means these boats rely on form stability at low heel angles. As the
                                              > boat heels, the water ballast rises above the waterline very quickly,
                                              > and becomes working ballast. The barge hull form runs out of form
                                              > stability quickly, and this is were the ballast becomes effective.
                                              > But only at fairly high heel angles, probably 20 degrees or more.
                                              > Most of us aren't used to sailing at those high angles any more.
                                              >
                                              > It enables a hull of very light trailering weight to also be self
                                              > righting (if she has either floation or a watertight cabin) from a
                                              > complete knockdown. Water ballast will also smooth out motion and
                                              > give a very light hull some momentum. In the case of the Macgregor it
                                              > enables a useable (and reasonably safe) sailboat, to dump her ballast
                                              > and plane off under outboard power. Another excellent feature is that
                                              > if your water ballasted boat is knocked down and fills, she will not
                                              > sink. Coupled with extremely shallow draft on launching, which can be
                                              > very handy, it makes sense.
                                              >
                                              > As always, horse's for course's.
                                              >
                                              > All the best, Tad.
                                              > -------------------------
                                              > The Chebacco, as designed, is just the form Tad suggests would
                                              > benefit from water ballast. I revised my Freeship model to put 500#
                                              > of water ballast in the 19' flat bottom boat and...
                                              >
                                              > ta daa - it is much stiffer than my round bottom idea. At a 20
                                              > degree angle of heel (sailing to windward in a fresh breeze, the flat
                                              > bottom water ballasted boat has a righting moment of 1880 ft-lbs, 30%
                                              > better than the round bottom boat and 80% more than the unballasted
                                              > boat. Evan at 5 and 10 degrees the water ballasted boat has almost
                                              > double the moment of the stock boat. The extra 500# causes the boat
                                              > to sink down just 1.5" deeper.
                                              >
                                              > The ballast tank is essentially a false bottom parallel to the
                                              > waterline and 5" deeep at its deepest point in the middle of the
                                              > boat. Sounds like an even better idea than the original post.
                                              >
                                              > Denny Wolfe
                                              >
                                              >
                                              While your at it put a fifty gallon inflatable holding bladder inside
                                              the water ballast tank
                                              that will expand when waste is pumped in and collaps when it is pumped
                                              out and you will have provided a conciderable amount of cruising time
                                              before pumping out with out any change of boat weight while in the
                                              water. Seems like a good idea to me???

                                              Doug
                                            • graeme19121984
                                              ... Wost case (Water ballast caught Bolger out once or twice): At what angle does the RM curve go negative - masts and all? Is there any bouyant volume of a
                                              Message 22 of 26 , Jan 12, 2009
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                                                --- In bolger@yahoogroups.com, "mcdennyw" <dwolfe@...> wrote:
                                                > At a 20 degree angle of heel (sailing to windward in a fresh
                                                > breeze, the flat bottom water ballasted boat has a righting moment
                                                > of 1880 ftlbs, 30% better than the round bottom boat and 80% more
                                                > than the unballasted boat. Evan at 5 and 10 degrees the water
                                                > ballasted boat has almost double the moment of the stock boat. The
                                                > extra 500# causes the boat to sink down just 1.5" deeper.

                                                Wost case (Water ballast caught Bolger out once or twice): At what
                                                angle does the RM curve go negative - masts and all? Is there any
                                                bouyant volume of a size that may concern at or near the same height
                                                as the water ballast -- eg under cockpit seats? Consider on beam ends
                                                wave rocking too.

                                                I'm just cautious that the ballast for extra RM for improved sailing
                                                in exhilarating conditions doesn't cause a boat that might otherwise
                                                rest on her side when knocked down to go... right over.

                                                Red Zinger, Beachcat, Chebaccos (mostly), etc, are the
                                                daysailing/cruising alternatives for those who want no messing with
                                                lead pouring... Well, certainly Beachcat has been described as such
                                                by PB&F. The OSTAR RACER #459 has a deep pivoting centreboard with
                                                distal, auto-trimming, winged ballast.

                                                Graeme
                                                (PS Talking of ostar and sharpie keels, and RM. gee, I can't believe
                                                #543 isn't in the database. sure it were once. will take a look later
                                                off-line)
                                              • mcdennyw
                                                Graeme, According to my Freeship model, the unballasted Chebacco (this is the lapstrake 19 offsets) righting moment goes negative at 93 degrees of heel.
                                                Message 23 of 26 , Jan 12, 2009
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                                                  Graeme,

                                                  According to my Freeship model, the unballasted Chebacco (this is the
                                                  lapstrake 19' offsets) righting moment goes negative at 93 degrees of
                                                  heel. Water ballasted as above has a RM of 950 ft-lbs at 93 degrees,
                                                  does not go negative until 107 degrees. This ignores any flotational
                                                  aspects of rig and assumes cockpit seats are water tight.

                                                  Max RM of unballasted boat is 1200 ft-lbs from 30 to 60 degrees.
                                                  Ballasted boat has RM of 2300 at 30, max of 2600 between 45 and 60
                                                  degrees.

                                                  If the boat were at 180 degrees, exactly turtle, I don't know it it
                                                  would come back upright or not. I'm pretty sure most all unballasted
                                                  boats are stable at 180 degrees.

                                                  For sure the ballasted boat would be a lot less likely to get upside
                                                  down in the first place.

                                                  Denny


                                                  >
                                                  > Wost case (Water ballast caught Bolger out once or twice): At what
                                                  > angle does the RM curve go negative - masts and all? Is there any
                                                  > bouyant volume of a size that may concern at or near the same
                                                  height
                                                  > as the water ballast -- eg under cockpit seats? Consider on beam
                                                  ends
                                                  > wave rocking too.
                                                  >
                                                  > I'm just cautious that the ballast for extra RM for improved
                                                  sailing
                                                  > in exhilarating conditions doesn't cause a boat that might
                                                  otherwise
                                                  > rest on her side when knocked down to go... right over.
                                                  >
                                                  > Red Zinger, Beachcat, Chebaccos (mostly), etc, are the
                                                  > daysailing/cruising alternatives for those who want no messing with
                                                  > lead pouring... Well, certainly Beachcat has been described as such
                                                  > by PB&F. The OSTAR RACER #459 has a deep pivoting centreboard with
                                                  > distal, auto-trimming, winged ballast.
                                                  >
                                                  > Graeme
                                                  > (PS Talking of ostar and sharpie keels, and RM. gee, I can't
                                                  believe
                                                  > #543 isn't in the database. sure it were once. will take a look
                                                  later
                                                  > off-line)
                                                  >
                                                • graeme19121984
                                                  Denny, that sounds all to be good. Great. I wonder how much different are the figures for the lead ballasted keel version. They d cost a little extra in the
                                                  Message 24 of 26 , Jan 13, 2009
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                                                    Denny,

                                                    that sounds all to be good. Great.

                                                    I wonder how much different are the figures for the lead ballasted
                                                    keel version. They'd cost a little extra in the 246lbs to trailer,
                                                    and another 6 inches of draft. I wonder if that lead ballast keel
                                                    might add a bit more than the 500lbs internal water ballast to
                                                    initial stability, but then not to final stability?

                                                    Graeme

                                                    --- In bolger@yahoogroups.com, "mcdennyw" <dwolfe@...> wrote:
                                                    >
                                                    > Graeme,
                                                    >
                                                    > According to my Freeship model, the unballasted Chebacco (this is
                                                    the
                                                    > lapstrake 19' offsets) righting moment goes negative at 93 degrees
                                                    of
                                                    > heel. Water ballasted as above has a RM of 950 ft-lbs at 93
                                                    degrees,
                                                    > does not go negative until 107 degrees. This ignores any
                                                    flotational
                                                    > aspects of rig and assumes cockpit seats are water tight.
                                                    >
                                                    > Max RM of unballasted boat is 1200 ft-lbs from 30 to 60 degrees.
                                                    > Ballasted boat has RM of 2300 at 30, max of 2600 between 45 and 60
                                                    > degrees.
                                                    >
                                                    > If the boat were at 180 degrees, exactly turtle, I don't know it it
                                                    > would come back upright or not. I'm pretty sure most all
                                                    unballasted
                                                    > boats are stable at 180 degrees.
                                                    >
                                                    > For sure the ballasted boat would be a lot less likely to get
                                                    upside
                                                    > down in the first place.
                                                    >
                                                    > Denny
                                                  • mcdennyw
                                                    Graeme, I modelled the full keel 246# lead ballast design (Bolger s Cruiser version) and the RM is right in between the no ballast and water ballast designs.
                                                    Message 25 of 26 , Jan 13, 2009
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                                                      Graeme,

                                                      I modelled the full keel 246# lead ballast design (Bolger's 'Cruiser'
                                                      version) and the RM is right in between the no ballast and water
                                                      ballast designs. At 20 degrees the 246# lead gives RM of 1393 ft-
                                                      lbs. No ballast RM is 1041, water ballast RM is 1883.

                                                      The vertical CG of the water ballasted boat is 2.5" lower than the
                                                      one with lead ballast. The lead is lower but only half the weight.:
                                                      >
                                                      > Denny,
                                                      >
                                                      > that sounds all to be good. Great.
                                                      >
                                                      > I wonder how much different are the figures for the lead ballasted
                                                      > keel version. They'd cost a little extra in the 246lbs to trailer,
                                                      > and another 6 inches of draft. I wonder if that lead ballast keel
                                                      > might add a bit more than the 500lbs internal water ballast to
                                                      > initial stability, but then not to final stability?
                                                      >
                                                      > Graeme
                                                      >
                                                    • graeme19121984
                                                      I missed that. Charles posted there was info about Big Tortoise in Instant Boatbuilding with Dynamite Payson . I browsed on to Catfish, a Chebacco spin-off,
                                                      Message 26 of 26 , Feb 6, 2009
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                                                        I missed that.

                                                        Charles' posted there was info about Big Tortoise in "Instant
                                                        Boatbuilding with Dynamite Payson". I browsed on to Catfish, a
                                                        Chebacco spin-off, and, blow me down, in the first short paragraph
                                                        Payson describes the self-righting and light trailering gained from
                                                        the free flooding keel under this design. I mean - it's the first
                                                        thing he jumps in at to describe!

                                                        PB&F have described aspects of the high and wide decks of Beachcat
                                                        that make for ease of mind in potential knock-down sailing
                                                        conditions. They mention the good ability of the salient keel in
                                                        thinner water than the centreboard of the upgrade plans can handle.
                                                        PCB seems to prefer the salient keel on Beachcat for himself, but to
                                                        my knowledge they have never elaborated on the benefits of the keel
                                                        being free flooding. Never published on this design aspect - I
                                                        thought it solid. This free-flooding/slow-draining is what adds so
                                                        much to Micro, supplemental to the lead ballast, in self-righting
                                                        immediately following a knockdown all the way to a beam ends attitude
                                                        where the keel is lifted above the water and before the internal
                                                        water has had time to drain out. The cross section of Beachcat
                                                        probably means that the flooded keel begins to lift above the water
                                                        and have a righting effect at more intermediate angles of heel than
                                                        on Micro, and keeps righting moment fairly positive as heeling
                                                        progresses for some arc beyond 90deg.

                                                        In a certain published vignette, that although un-named could only
                                                        have featured cruising aboard an original Catfish, a prominent Aussie
                                                        designer/builder didn't mention the designed benefits of freely
                                                        flooding the Catfish keel. Has Mr Payson got his wires crossed?

                                                        Graeme



                                                        --- In bolger@yahoogroups.com, "mcdennyw" <dwolfe@...> wrote:
                                                        >
                                                        > Graeme,
                                                        >
                                                        > I modelled the full keel 246# lead ballast design
                                                        (Bolger's 'Cruiser'
                                                        > version) and the RM is right in between the no ballast and water
                                                        > ballast designs. At 20 degrees the 246# lead gives RM of 1393 ft-
                                                        > lbs. No ballast RM is 1041, water ballast RM is 1883.
                                                        >
                                                        > The vertical CG of the water ballasted boat is 2.5" lower than the
                                                        > one with lead ballast. The lead is lower but only half the weight.:
                                                        > >
                                                        > > Denny,
                                                        > >
                                                        > > that sounds all to be good. Great.
                                                        > >
                                                        > > I wonder how much different are the figures for the lead
                                                        ballasted
                                                        > > keel version. They'd cost a little extra in the 246lbs to
                                                        trailer,
                                                        > > and another 6 inches of draft. I wonder if that lead ballast keel
                                                        > > might add a bit more than the 500lbs internal water ballast to
                                                        > > initial stability, but then not to final stability?
                                                        > >
                                                        > > Graeme
                                                        > >
                                                        >
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