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Aerated Power Boat Bottoms /Sneakeasy

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  • dbaldnz
    Not strictly a Bolger topic, but an addition to the current Wyo/Sneakeasy bottom discussion. During the 1960 s, a modern pioneer multihull designer and
    Message 1 of 11 , Sep 30, 2002
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      Not strictly a Bolger topic, but an addition to the current
      Wyo/Sneakeasy bottom discussion.
      During the 1960's, a modern pioneer multihull designer and
      aerodynamics engineer, J.S. Taylor in Australia, built a 23ft ocean
      going sailing trimaran called Maui. It sailed 306 miles in 24 hours
      at sea, remarkable at that time for such a small sailing cruiser.
      The boat had a low deadrise chine hull. The interesting innovation
      however was the double bottom with air space between. Along the
      bottom of the hull, running diagonally from keel to chine, were
      close spaced narrow slits. The air in the bottom space was slightly
      pressurized by a battery driven fan, causing a carpet of bubbles to
      disperse right along the bottom of the hull. I don't know if the
      bubbles acted like a carpet of ball bearings, or whether they
      sheared and lessened resistance. Magazine articles were published at
      the time, but I have seen nothing like it since. Perhaps others have
      tried the idea, and I wondered whether it may be applicable to the
      fast powerboats being discussed in this Group.
      DonB
    • tom28571
      ... ocean ... hours ... slightly ... to ... at ... have ... Don, Many powerboat designers and experimenters have tried aeriating the hull bottom but usually
      Message 2 of 11 , Sep 30, 2002
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        --- In bolger@y..., "dbaldnz" <oink@p...> wrote:
        > Not strictly a Bolger topic, but an addition to the current
        > Wyo/Sneakeasy bottom discussion.
        > During the 1960's, a modern pioneer multihull designer and
        > aerodynamics engineer, J.S. Taylor in Australia, built a 23ft
        ocean
        > going sailing trimaran called Maui. It sailed 306 miles in 24
        hours
        > at sea, remarkable at that time for such a small sailing cruiser.
        > The boat had a low deadrise chine hull. The interesting innovation
        > however was the double bottom with air space between. Along the
        > bottom of the hull, running diagonally from keel to chine, were
        > close spaced narrow slits. The air in the bottom space was
        slightly
        > pressurized by a battery driven fan, causing a carpet of bubbles
        to
        > disperse right along the bottom of the hull. I don't know if the
        > bubbles acted like a carpet of ball bearings, or whether they
        > sheared and lessened resistance. Magazine articles were published
        at
        > the time, but I have seen nothing like it since. Perhaps others
        have
        > tried the idea, and I wondered whether it may be applicable to the
        > fast powerboats being discussed in this Group.
        > DonB

        Don,

        Many powerboat designers and experimenters have tried aeriating the
        hull bottom but usually with step bottoms. Some have used air
        inlets to augment the air that gets in the normal way through the
        chine area and a few have closed off the chine at the step and
        supplied all the air from the deck by power fans. Some have routed
        the engine exhaust through the bottom. I have not heard of it being
        done on a sailboat as you speak of though.

        Tom
      • dbaldnz
        Hi Tom, have you ever heard whether whether there is a speed improvement? DonB ... the ... routed ... being
        Message 3 of 11 , Sep 30, 2002
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          Hi Tom, have you ever heard whether whether there is a speed
          improvement?
          DonB

          > Don,
          >
          > Many powerboat designers and experimenters have tried aeriating
          the
          > hull bottom but usually with step bottoms. Some have used air
          > inlets to augment the air that gets in the normal way through the
          > chine area and a few have closed off the chine at the step and
          > supplied all the air from the deck by power fans. Some have
          routed
          > the engine exhaust through the bottom. I have not heard of it
          being
          > done on a sailboat as you speak of though.
          >
          > Tom
        • John Bell
          During the BOC back in 94?, the Open 60 Hunter s Child had a such a system installed. When the boat reached a certain was supposed to aspirate air through a
          Message 4 of 11 , Sep 30, 2002
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            During the BOC back in 94?, the Open 60 "Hunter's Child" had a such a system
            installed. When the boat reached a certain was supposed to aspirate air
            through a series of holes in the bottom aft of the keel, reducing frictional
            drag. They got it to work, but I never heard if it actually helped.

            JB

            ----- Original Message -----
            From: "dbaldnz" <oink@...>
            To: <bolger@yahoogroups.com>
            Sent: Monday, September 30, 2002 7:56 PM
            Subject: [bolger] Re: Aerated Power Boat Bottoms /Sneakeasy


            | Hi Tom, have you ever heard whether whether there is a speed
            | improvement?
            | DonB
            |
            | > Don,
            | >
            | > Many powerboat designers and experimenters have tried aeriating
            | the
            | > hull bottom but usually with step bottoms. Some have used air
            | > inlets to augment the air that gets in the normal way through the
            | > chine area and a few have closed off the chine at the step and
            | > supplied all the air from the deck by power fans. Some have
            | routed
            | > the engine exhaust through the bottom. I have not heard of it
            | being
            | > done on a sailboat as you speak of though.
            | >
            | > Tom
            |
            |
            |
            | Bolger rules!!!
            | - no cursing, flaming, trolling, spamming, or flogging dead horses
            | - stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
            | - add your comments at the TOP and SIGN your posts and <snip> away
            | - To order plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA,
            01930, Fax: (978) 282-1349
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            |
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            |
            |
          • tom28571
            ... Don, I have not heard or don t remember any specific data on speed improvement from introducing air under a boat without steps. Of course, if sufficient
            Message 5 of 11 , Sep 30, 2002
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              --- In bolger@y..., "dbaldnz" <oink@p...> wrote:
              > Hi Tom, have you ever heard whether whether there is a speed
              > improvement?
              > DonB
              >
              >
              Don, I have not heard or don't remember any specific data on speed
              improvement from introducing air under a boat without steps. Of
              course, if sufficient air is not let in behind a step, there will be
              a lot of added drag. I will check to see if Marchaj has anything to
              say about that.

              John, I did not know about the keel thing on Thursday's Child and
              would be skeptical that any naturally aspirated system could work on
              a keel since it is so far below the water. Also, because of
              increasing pressure, probably none of the air could get past the
              highest openings in the keel if it did work at all.
            • John Bell
              Tom, It was aft of the keel, on the canoe body underneath the cockpit. It wasn t installed until the last leg of the race from South America to the finish in
              Message 6 of 11 , Sep 30, 2002
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                Tom,

                It was aft of the keel, on the canoe body underneath the cockpit. It wasn't
                installed until the last leg of the race from South America to the finish in
                Charleston, SC. There was precious little coverage at the time, but I
                distinctly remember reading about in on Compuserve Sailing forum so long
                ago.

                JB

                ----- Original Message -----
                From: "tom28571" <harbinger@...>
                To: <bolger@yahoogroups.com>
                Sent: Monday, September 30, 2002 10:41 PM
                Subject: [bolger] Re: Aerated Power Boat Bottoms /Sneakeasy


                | --- In bolger@y..., "dbaldnz" <oink@p...> wrote:
                | > Hi Tom, have you ever heard whether whether there is a speed
                | > improvement?
                | > DonB
                | >
                | >
                | Don, I have not heard or don't remember any specific data on speed
                | improvement from introducing air under a boat without steps. Of
                | course, if sufficient air is not let in behind a step, there will be
                | a lot of added drag. I will check to see if Marchaj has anything to
                | say about that.
                |
                | John, I did not know about the keel thing on Thursday's Child and
                | would be skeptical that any naturally aspirated system could work on
                | a keel since it is so far below the water. Also, because of
                | increasing pressure, probably none of the air could get past the
                | highest openings in the keel if it did work at all.
                |
                |
                |
                | Bolger rules!!!
                | - no cursing, flaming, trolling, spamming, or flogging dead horses
                | - stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
                | - add your comments at the TOP and SIGN your posts and <snip> away
                | - To order 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
                |
                | Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                |
                |
              • tom28571
                ... It wasn t ... finish in ... but I ... so long ... John, I was sailing around with 500 other boats in the starting area for that 94 BOC race off the jetty
                Message 7 of 11 , Sep 30, 2002
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                  --- In bolger@y..., "John Bell" <jmbell@m...> wrote:
                  > Tom,
                  >
                  > It was aft of the keel, on the canoe body underneath the cockpit.
                  It wasn't
                  > installed until the last leg of the race from South America to the
                  finish in
                  > Charleston, SC. There was precious little coverage at the time,
                  but I
                  > distinctly remember reading about in on Compuserve Sailing forum
                  so long
                  > ago.
                  >
                  > JB
                  >

                  John, I was sailing around with 500 other boats in the starting
                  area for that '94 BOC race off the jetty in Charleston. It was
                  amazing.

                  I still don't see how they could get enough pressure differential to
                  pull air through the hull at that point without introducing drag
                  that might be greater than the benefit, but what do I know? The
                  Laser tried that on the original models but it never worked as a
                  bailer until they put in the extended venturi.

                  Tom
                • Chance Curtis
                  The bubbles might have more to do with turbulence. The US Navy did studies of this affect on fish with scales vs fishskin like sharks. Fish with scales are
                  Message 8 of 11 , Oct 1, 2002
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                    The bubbles might have more to do with turbulence. The US Navy did studies of this affect on fish with scales vs fishskin like sharks. Fish with scales are faster but fish with skin are quieter. The navy did develop subs producing bubbles and they were faster, but those Sonobouys could hear them coming miles away.
                    CCG
                    dbaldnz wrote:Not strictly a Bolger topic, but an addition to the current
                    Wyo/Sneakeasy bottom discussion.
                    During the 1960's, a modern pioneer multihull designer and
                    aerodynamics engineer, J.S. Taylor in Australia, built a 23ft ocean
                    going sailing trimaran called Maui. It sailed 306 miles in 24 hours
                    at sea, remarkable at that time for such a small sailing cruiser.
                    The boat had a low deadrise chine hull. The interesting innovation
                    however was the double bottom with air space between. Along the
                    bottom of the hull, running diagonally from keel to chine, were
                    close spaced narrow slits. The air in the bottom space was slightly
                    pressurized by a battery driven fan, causing a carpet of bubbles to
                    disperse right along the bottom of the hull. I don't know if the
                    bubbles acted like a carpet of ball bearings, or whether they
                    sheared and lessened resistance. Magazine articles were published at
                    the time, but I have seen nothing like it since. Perhaps others have
                    tried the idea, and I wondered whether it may be applicable to the
                    fast powerboats being discussed in this Group.
                    DonB



                    Bolger rules!!!
                    - no cursing, flaming, trolling, spamming, or flogging dead horses
                    - stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
                    - add your comments at the TOP and SIGN your posts and <snip> away
                    - To order 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

                    Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.



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                    [Non-text portions of this message have been removed]
                  • John Cupp
                    This concept is already in production by the US for their Seal Teams. They have a heavily modified, narrow beam, step chined boat that can cruise at 70 knots
                    Message 9 of 11 , Oct 1, 2002
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                      This concept is already in production by the US for their Seal
                      Teams. They have a heavily modified, narrow beam, step chined boat
                      that can cruise at 70 knots with an ultra smooth ride. Very Slender
                      Vessel (VSV). The VSV is designed as a wave piercing craft; in lieu
                      of the standard high speed boat, which produces an extremely
                      uncomfortable ride over long, high-speed transits in higher sea
                      states. The VSV is expected to deliver SEAL or other SOF operators to
                      objective areas who are much more mission capable.
                      Check out the photo's I put up at Bolger 2.

                      http://groups.yahoo.com/group/Bolger2/files/Modified%20Sneakeasy/

                      These boats are very fuel efficient but they give no details of the
                      power supply's or how they induce the air under the hull be it fans
                      or venturi effect. They are amazing craft and not to far from the
                      Wyo/Sneakeasy profile. I also am adding a picture of an air assisted
                      test bed catamaran. The 'Surface-effect-cat' concept is an air-
                      assisted catamaran with wave-slicing fine-entry side hulls. Air is
                      blown into the recesses in the side-hulls. This method of lift
                      reduces power requirements to about 1/2 that of a conventional
                      catamaran at cruise speed.

                      I also took the liberty to use another designers concept boat as a
                      modified Sneakeasy with reverse bow. It would not be hard to modify
                      the Sneakeasy the same way. With a LWL at 38' a little air induction
                      from a cyclone air bilge pump on the drive shaft and it would be a
                      very sexy missile. The picture is in the same file, a sort of art-
                      nouveau Sneakeasy. Looks cool anyway.

                      John




                      --- In bolger@y..., Chance Curtis <sneakeasy2002@y...> wrote:
                      >
                      > The bubbles might have more to do with turbulence. The US Navy did
                      studies of this affect on fish with scales vs fishskin like sharks.
                      Fish with scales are faster but fish with skin are quieter. The navy
                      did develop subs producing bubbles and they were faster, but those
                      Sonobouys could hear them coming miles away.
                      > CCG
                      > dbaldnz wrote:Not strictly a Bolger topic, but an addition to the
                      current
                      > Wyo/Sneakeasy bottom discussion.
                      > During the 1960's, a modern pioneer multihull designer and
                      > aerodynamics engineer, J.S. Taylor in Australia, built a 23ft ocean
                      > going sailing trimaran called Maui. It sailed 306 miles in 24 hours
                      > at sea, remarkable at that time for such a small sailing cruiser.
                      > The boat had a low deadrise chine hull. The interesting innovation
                      > however was the double bottom with air space between. Along the
                      > bottom of the hull, running diagonally from keel to chine, were
                      > close spaced narrow slits. The air in the bottom space was slightly
                      > pressurized by a battery driven fan, causing a carpet of bubbles to
                      > disperse right along the bottom of the hull. I don't know if the
                      > bubbles acted like a carpet of ball bearings, or whether they
                      > sheared and lessened resistance. Magazine articles were published
                      at
                      > the time, but I have seen nothing like it since. Perhaps others
                      have
                      > tried the idea, and I wondered whether it may be applicable to the
                      > fast powerboats being discussed in this Group.
                      > DonB
                      >
                      >
                      >
                      > Bolger rules!!!
                      > - no cursing, flaming, trolling, spamming, or flogging dead horses
                      > - stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred'
                      posts
                      > - add your comments at the TOP and SIGN your posts and <snip>
                      away
                      > - To order plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester,
                      MA, 01930, Fax: (978) 282-1349
                      > - Unsubscribe: bolger-unsubscribe@y...
                      > - Open discussion: bolger_coffee_lounge-subscribe@y...
                      >
                      > Your use of Yahoo! Groups is subject to the Yahoo! Terms of
                      Service.
                      >
                      >
                      >
                      > ---------------------------------
                      > Do you Yahoo!?
                      > New DSL Internet Access from SBC & Yahoo!
                      >
                      > [Non-text portions of this message have been removed]
                    • pvanderwaart
                      I believe that Project Amazon, an around-the-world singlehander also had an aeration scheme. The boat was designed by Eric Sponberg, but as I recall, the
                      Message 10 of 11 , Oct 1, 2002
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                        I believe that Project Amazon, an around-the-world singlehander also
                        had an aeration scheme. The boat was designed by Eric Sponberg, but
                        as I recall, the aeration was the owners design. Sponberg's web site
                        doesn't have details of the design anymore. Maybe someone out there
                        knows more.

                        http://www.sponbergyachtdesign.com/SailDesigns.htm

                        Peter
                      • John Bell
                        I just heard from someone on the WB forum who s been around Hunter s Child and confirmed that it does in fact have the aeration system. She s going to ask
                        Message 11 of 11 , Oct 1, 2002
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                          I just heard from someone on the WB forum who's been around Hunter's Child
                          and confirmed that it does in fact have the aeration system. She's going to
                          ask Steve Pettingill how it worked for me.

                          JB


                          ----- Original Message -----
                          From: "tom28571" <harbinger@...>
                          | I still don't see how they could get enough pressure differential to
                          | pull air through the hull at that point without introducing drag
                          | that might be greater than the benefit, but what do I know? The
                          | Laser tried that on the original models but it never worked as a
                          | bailer until they put in the extended venturi.
                          |
                          |
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