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External chines (runners?)

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  • saillips
    As we seem to have many multi-forum members, I d like to ask the Bolgeristas who have built Birdwatchers or other Bolger sailing designs with external chine
    Message 1 of 8 , Aug 30 1:46 PM
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      As we seem to have many multi-forum members, I'd like to ask the
      Bolgeristas who have built Birdwatchers or other Bolger sailing
      designs with external chine logs if they have found these to function
      as "chine runners" (Paradox, micro-cruising forum)? I mean, do you
      think they help sail to windward in thin water with the board up?
      Just interested, and hopeful!
      Thanks, David
    • Paul
      My tortoise, which has external chines, will not go to windward without the board down Paul H
      Message 2 of 8 , Aug 30 2:15 PM
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        My tortoise, which has external chines, will not go to windward without
        the board down

        Paul H

        --- In bolger@yahoogroups.com, "saillips" <saillips@...> wrote:
        >
        > As we seem to have many multi-forum members, I'd like to ask the
        > Bolgeristas who have built Birdwatchers or other Bolger sailing
        > designs with external chine logs if they have found these to function
        > as "chine runners" (Paradox, micro-cruising forum)? I mean, do you
        > think they help sail to windward in thin water with the board up?
        > Just interested, and hopeful!
        > Thanks, David
        >
      • Doug
        ... When I was talking to Bolger about designing Wolftrap about 1979 I told him I had admired Black Skimmer and he said she would have been a better boat had
        Message 3 of 8 , Aug 30 2:28 PM
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          saillips wrote:
          >
          > As we seem to have many multi-forum members, I'd like to ask the
          > Bolgeristas who have built Birdwatchers or other Bolger sailing
          > designs with external chine logs if they have found these to function
          > as "chine runners" (Paradox, micro-cruising forum)? I mean, do you
          > think they help sail to windward in thin water with the board up?
          > Just interested, and hopeful!
          > Thanks, David
          >
          >
          When I was talking to Bolger about designing Wolftrap about 1979
          I told him I had admired Black Skimmer and he said she would have been a
          better boat had her chines been inside and there had been a little
          refinement to her hull. The outside chines were strickly to make her
          easy to build. That was at least my understanding.

          Doug
        • John and Kathy Trussell
          PCB s essay on Light Dory in Small Boats states that the external chines may reduce turbulance at the chines and add slightly to stability, but I ve never seen
          Message 4 of 8 , Aug 30 5:10 PM
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            PCB's essay on Light Dory in Small Boats states that the external chines may reduce turbulance at the chines and add slightly to stability, but I've never seen anything that suggests that they prevent leeway.

            Conrad Natzio in England sells plans for various flat bottomed boats and at one time had a flat bottomed pram with runners on the bottom which he said allowed the boat to sail upwind. However, he has not incorporated this feature in subsequent designs and I infer that the runners were not that effective.

            I had a Bolger Sweet Pea with a long, shallow keel. I could point somewhere around 50 degrees, but that may have been due to a very small sprit sail.

            John T
            ----- Original Message -----
            From: Paul
            To: bolger@yahoogroups.com
            Sent: Wednesday, August 30, 2006 5:15 PM
            Subject: [bolger] Re: External chines (runners?)


            My tortoise, which has external chines, will not go to windward without
            the board down

            Paul H

            --- In bolger@yahoogroups.com, "saillips" <saillips@...> wrote:
            >
            > As we seem to have many multi-forum members, I'd like to ask the
            > Bolgeristas who have built Birdwatchers or other Bolger sailing
            > designs with external chine logs if they have found these to function
            > as "chine runners" (Paradox, micro-cruising forum)? I mean, do you
            > think they help sail to windward in thin water with the board up?
            > Just interested, and hopeful!
            > Thanks, David
            >






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          • Patrick Crockett
            It is my impression that the external chine logs help a bit -- more when reaching in light air than when beating. Without a good bit of daggerboard showing,
            Message 5 of 8 , Aug 30 7:15 PM
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              It is my impression that the external chine logs help a bit -- more when
              reaching in light air than when beating. Without a good bit of
              daggerboard showing, the boat doesn't make much good to windward. Of
              course, here in North Carolina, when the water is too thin for the
              board, you might as well get out and walk, pulling the boat behind.

              Patrick

              saillips wrote:
              > As we seem to have many multi-forum members, I'd like to ask the
              > Bolgeristas who have built Birdwatchers or other Bolger sailing
              > designs with external chine logs if they have found these to function
              > as "chine runners" (Paradox, micro-cruising forum)? I mean, do you
              > think they help sail to windward in thin water with the board up?
              > Just interested, and hopeful!
              > Thanks, David
              >
              >
              >
              >
              >
              > 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
              >
              >
              >
              >
              >
              >
              >
              >
            • gbship
              My old Zephyr would point hard on the wind without any leeboard, but with noticeable leeway. Zephyr also has bottom skids and a central 1.5 x 1.5 inch keel
              Message 6 of 8 , Aug 30 10:02 PM
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                My old Zephyr would point hard on the wind without any leeboard, but
                with noticeable leeway. Zephyr also has bottom skids and a central
                1.5 x 1.5 inch "keel" which may have helped. Obviously tacking was
                unreliable, but I did manage to tack it a couple times in good
                breezes without the leeboard down. Like Patrick said, if your
                destination is dead upwind, it might be better to get out and tow the
                boat -- and certainly gteat exercise for your legs . . .

                Gary

                --- In bolger@yahoogroups.com, Patrick Crockett <pcrockett@...> wrote:
                >
                > It is my impression that the external chine logs help a bit -- more
                when
                > reaching in light air than when beating. Without a good bit of
                > daggerboard showing, the boat doesn't make much good to windward.
                Of
                > course, here in North Carolina, when the water is too thin for the
                > board, you might as well get out and walk, pulling the boat behind.
                >
                > Patrick
                >
                > saillips wrote:
                > > As we seem to have many multi-forum members, I'd like to ask the
                > > Bolgeristas who have built Birdwatchers or other Bolger sailing
                > > designs with external chine logs if they have found these to
                function
                > > as "chine runners" (Paradox, micro-cruising forum)? I mean, do you
                > > think they help sail to windward in thin water with the board up?
                > > Just interested, and hopeful!
                > > Thanks, David
                > >
                > >
                > >
                > >
                > >
                > > 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
                > >
                > >
                > >
                > >
                > >
                > >
                > >
                > >
                >
              • Martyn Aldis
                In message , John and Kathy Trussell writes ... I have an Oyster Catcher built to Corned
                Message 7 of 8 , Sep 1, 2006
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                  In message <00eb01c6cc92$25f87810$0a00a8c0@oemcomputer>, John and Kathy
                  Trussell <jtrussell2@...> writes
                  >PCB's essay on Light Dory in Small Boats states that the external
                  >chines may reduce turbulance at the chines and add slightly to
                  >stability, but I've never seen anything that suggests that they prevent
                  >leeway.
                  >
                  >Conrad Natzio in England sells plans for various flat bottomed boats
                  >and at one time had a flat bottomed pram with runners on the bottom
                  >which he said allowed the boat to sail upwind. However, he has not
                  >incorporated this feature in subsequent designs and I infer that the
                  >runners were not that effective.

                  I have an Oyster Catcher built to Corned Nato plans. There is far too
                  little lateral area. Even an oyster could escape if it jumped up-wind a
                  few times.

                  The old off-centre board is becoming the rudder blade and a new tilt
                  dagger board is under construction. It may even work.

                  The other boat we have with external chines is a Tortoise and I think
                  that may have too much "foils" area - I'm going to try a Mirror rudder
                  as the large one on the plan is so sensitive.

                  About deference to the designer's intentions. One great advantage of the
                  books is that PCB gives us hints about why he did what he did and he
                  often has variations on a theme. I would not put a full stern deck on a
                  Tortoise again. It makes it very difficult to get the crew weight were
                  it is needed running in a breeze and as we don't get ice in our harbour
                  and do not go mud larding I have no need of the deck to flop on when the
                  ice gives way or my boot hits a soft patch of mud. The Brick does not
                  have the full deck.

                  A modification I made on the Tortoise that worked well was to use the
                  "New Instant Boats" smooth glass chine for the ends of the bottom and
                  the original external chine for the sides. I've added topping lifts
                  (Lazy Jacks) to the lateen rig and they are really worthwhile. I can now
                  rig the boat with the sail in the lifts and wheel it to the water and be
                  away fast and without the yard going in the sea. Similarly the sail
                  doesn't smoother me at the end of the outing. This would have been
                  useful in 1990 when we first rigged the boat and our son was a child.
                  --

                  Martyn Aldis, e-mail martyn.aldis@...
                  ==============================================================================
                • graeme19121984
                  Hi David, the small sharpie designs of Matt Leyden have done well in his hands, especially in competition. There is a high degee of interest in the chine
                  Message 8 of 8 , Sep 1, 2006
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                    Hi David,

                    the small sharpie designs of Matt Leyden have done well in his
                    hands, especially in competition. There is a high degee of interest
                    in the chine runners of his later designs, and much speculation as
                    to how they may or may not work to affect the performance of flat
                    bottomed sailing boats. I predict zillions of his Enigma design will
                    be built if he makes them available. Quite a few people are
                    pondering on the effect(s) of chine logs, and more on the possibly
                    derived chine-runners. Among many interesting theories are that they
                    may reduce turbulence, perhaps by an end-plate effect, or by
                    turbulence suppressing and lift generating chine anti-vortexes.
                    AFAIK PCB is mute on this point.


                    PCB mentions a number of the chine effects on sailing sharpies under
                    way, but as far as I know never has said they generate lift to
                    windward, or signifcantly reduce leeway. Apart from the detrimental
                    effects of the sharpie chine (especially at the bow) positives
                    include: an increase in water line length when heeled, with
                    commensurate increase in waterline L/B; and reduction in pounding
                    and resistance when heeled (but he also notes that sharpies should
                    be sailed flat?). There may be more.

                    In considering the Light Dory Type V rowboat external chine log
                    effects PCB does not touch on any that may be possibly of interest
                    to the consideration of sailing hull performance other than to
                    comment on two things: a minute increase of stability; and that he
                    thinks they cause no increase in resistance (being effectively
                    neutral). He is mute as to their effect on turbulence. He observes
                    at various times that the means of reducing the phenomenon of
                    sharpie chine vortex turbulence is to have equal curvature of the
                    chine line in profile and plan views. AFAIK he doesn't consider
                    external chine logs in this regard specifically, but an indicator
                    may be that of the sailing sharpies he has designed to conform to
                    this theory very few have such chine logs. Even there I'm not so
                    sure those designs such as Black Skimmer, and Flying Schooner, fully
                    conform to the theory at the bow when under way.

                    An English "Brick" sailor recently posted to the micro-cruising
                    group that he noted better windward performance the more he heeled
                    the boat by shifting his weight to the lee side. He noted that the
                    heeled immersed shape reminded him of a type of wing section used on
                    rubber band powered model planes. Many proa authorities think
                    certain types of pacific proa gain lift to windward from a similar,
                    if stretched, immersed shape. There is an old September 98 MAIB
                    article, "Dreamboats", that also may give some pointers as to how a
                    flat bottomed boat may be helped to windward by assuming a vesica
                    form when heeled:

                    http://www.messingaboutinboats.com/archives/mbissueseptember15-
                    98.html

                    It may be that chine-runners, and even chine logs in a small way,
                    reduce turbulence and help sail to windward. There is much ground
                    for speculation in the absence of testing. However, PCB "knows more
                    about sharpies than anyone alive", and if he knows he hasn't said
                    (AFAIK).

                    Graeme

                    --- In bolger@yahoogroups.com, "saillips" <saillips@...> wrote:
                    >
                    > As we seem to have many multi-forum members, I'd like to ask the
                    > Bolgeristas who have built Birdwatchers or other Bolger sailing
                    > designs with external chine logs if they have found these to
                    function
                    > as "chine runners" (Paradox, micro-cruising forum)? I mean, do you
                    > think they help sail to windward in thin water with the board up?
                    > Just interested, and hopeful!
                    > Thanks, David
                    >
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