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Re: Easy build catamaran thoughts invited.

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  • graeme19121984
    ... Ah, so that s a 5.5Ft plug in Toto now? Is it really that easy? ~ Graeme ~ ___/) ~ ~
    Message 1 of 24 , Oct 4, 2009
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      --- In Michalak@yahoogroups.com, "gary" <gbship@...> wrote:
      > I am, with Jim M's advice, building a 4-foot longer version of
      > Trilars. That can cruise two for a long time, and carry three on
      > short trips.

      Ah, so that's a 5.5Ft plug in Toto now? Is it really that easy?

      ~ Graeme ~ ___/) ~ ~
    • graeme19121984
      ... If there s a good sailing wind there, then there is certainly chop, and further, close by the reef it s often wind against fast current. For family
      Message 2 of 24 , Oct 4, 2009
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        --- In Michalak@yahoogroups.com, duncan mills <duncanmillsoftassie@...> wrote:
        >
        > Having study "instant boat" design for the last couple of years , I am interested in adapting the hull forms for a low cost trailerable family cruising trimaran. I welcome feed back on the idea.
        > My first thoughts would be using the Dorado hull, with modified Toto canoe hulls for amas.
        > The objective to achieve quick to build easily driven multihull forms that can plane easily while cutting though chop. Lateral resistance would be supplied by M style leefoils and folding foil type rudder. The environment is tropic semi protected waters. (inside > Aust East coast barrier reef)
        >


        If there's a good sailing wind there, then there is certainly chop, and further, close by the reef it's often wind against fast current. For family comfort, if for no other reason, your tri will have to cater for that. There is likely to be the 2 out of three problem, you know: economy, speed, or comfort - pick any two. One of Tom Jones' boats might be the closest modern ticket to all three. (Bolger said TFJ did all his own thinking. High praise.)



        > The amas would hinge on turntable underneath the sides of an over hull width cabin. A cabin consrued as a full length flat bottomed secondary hull type superstructure of ply bent to semi airfoil section but with full length poptop midsection for tropical comfort.
        > Rig would be high set balanced lug on A frame mast with genoa jib.
        >

        There's a lot of small folding tri designs around. I don't know if you'd ever get away with 'instant', though some go close and might do. Rig is an issue. I reckon your query might be best put to the knowledgeable and helpful people in the multhull_boatbuilder group at http://groups.yahoo.com/group/multihull_boatbuilder/

        ~ Graeme ~ ___/) ~ ~
      • gary
        I think it s a 6.5 foot plug but as far as I can tell, that s the only change. I don t have a separate set up plans, but have been building from the Trilars
        Message 3 of 24 , Oct 4, 2009
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          I think it's a 6.5 foot plug but as far as I can tell, that's the only change. I don't have a separate set up plans, but have been building from the Trilars plans with 4-foot sections added in the appropriate areas. the hardest to do (I haven't gotten to it yet) will be the side decks because those extentions are tapered whereas those on the hull are straight.

          Another thought on cheap tris is Bolger once did a design where the builder did the main hull and then used an old Hobie 16 for the amas, cross beams & rig. Had one of his sugar scoop bows. I think hull was around 4 feet wide and around 20 feet long (may have been longer) and could sleep four under its low decks in a pinch. Had a center cockpit. Interesting design, althought the bow gave some concerns for punching through the square waves we get in shallow waters around here.

          Gary


          --- In Michalak@yahoogroups.com, "graeme19121984" <graeme19121984@...> wrote:
          >
          >
          >
          >
          >
          > --- In Michalak@yahoogroups.com, "gary" <gbship@> wrote:
          > > I am, with Jim M's advice, building a 4-foot longer version of
          > > Trilars. That can cruise two for a long time, and carry three on
          > > short trips.
          >
          > Ah, so that's a 5.5Ft plug in Toto now? Is it really that easy?
          >
          > ~ Graeme ~ ___/) ~ ~
          >
        • Douglas Pollard
          ... Graeme, I don t know if this will make any difference to your thinking or not. It s my understanding that catamarans do not plane and that they go fast
          Message 4 of 24 , Oct 4, 2009
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            graeme19121984 wrote:
            >
            >
            >
            >
            > --- In Michalak@yahoogroups.com <mailto:Michalak%40yahoogroups.com>,
            > "gary" <gbship@...> wrote:
            > > I am, with Jim M's advice, building a 4-foot longer version of
            > > Trilars. That can cruise two for a long time, and carry three on
            > > short trips.
            >
            > Ah, so that's a 5.5Ft plug in Toto now? Is it really that easy?
            >
            > ~ Graeme ~ ___/) ~ ~
            >
            >
            Graeme,
            I don't know if this will make any difference to your thinking or
            not. It's my understanding that catamarans do not plane and that they
            go fast because of the narrowness of hulls providing a very high hull
            speed. I don't know about Trimarans with the center hull wider they my
            plane on the center hull and just have high hull speeds on the outer
            hulls. I have no idea if this applies to what you are doing but thought
            to throw it out for consideration.


            Doug
          • Douglas Pollard
            ... I guess what I was thinking when I wrote the previous post is. That the modern 30ft ish trimarans I have seen have very narrow center hulls that widen out
            Message 5 of 24 , Oct 4, 2009
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              Douglas Pollard wrote:
              >
              >
              > graeme19121984 wrote:
              > >
              > >
              > >
              > >
              > > --- In Michalak@yahoogroups.com <mailto:Michalak%40yahoogroups.com>
              > <mailto:Michalak%40yahoogroups.com>,
              > > "gary" <gbship@...> wrote:
              > > > I am, with Jim M's advice, building a 4-foot longer version of
              > > > Trilars. That can cruise two for a long time, and carry three on
              > > > short trips.
              > >
              > > Ah, so that's a 5.5Ft plug in Toto now? Is it really that easy?
              > >
              > > ~ Graeme ~ ___/) ~ ~
              > >
              > >
              > Graeme,
              > I don't know if this will make any difference to your thinking or
              > not. It's my understanding that catamarans do not plane and that they
              > go fast because of the narrowness of hulls providing a very high hull
              > speed. I don't know about Trimarans with the center hull wider they my
              > plane on the center hull and just have high hull speeds on the outer
              > hulls. I have no idea if this applies to what you are doing but thought
              > to throw it out for consideration.
              >
              >
              > Doug
              >
              >
              I guess what I was thinking when I wrote the previous post is. That the
              modern 30ft'ish trimarans I have seen have very narrow center hulls that
              widen out above the water line. They basically have a long narrow foot
              well in side the boat with bunks on either side. These extremely
              narrow center hulls also have very high hull speeds. But a small
              trimaran would seem to need a wide hull amidships to have any usable
              space. A wide hull would have to plane. I'm wondering if the bow would
              be able to climb on top the water and drop down on a plane at some
              speed. With the outer hulls not planing the main hull would have to lift
              them as well. AS they lift at the bow the hull in the water would get
              shorter so hull speed would go down. They would not likely plane with
              such a narrow none plaining hull shape. Would they then drag the
              center hull speed down. I don't pretend to know much about trimarans
              but these are kind of my what if's. I would like to hear some
              thinking on these musings. Doug
            • graeme19121984
              ... 19.5Ft. WL of say, 19ft. Fineness ratio now 19/2.5=7.6. Looking good for a cruising tri. Are you also lengthening the amas? Moving their bows forward? I
              Message 6 of 24 , Oct 4, 2009
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                --- In Michalak@yahoogroups.com, "gary" <gbship@...> wrote:
                >
                > I think it's a 6.5 foot plug but as far as I can tell, that's the only change. I don't have a separate set up plans, but have been building from the Trilars plans with 4-foot sections added in the appropriate areas. the hardest to do (I haven't gotten to it yet) will be the side decks because those extentions are tapered whereas those on the hull are straight.
                >

                19.5Ft. WL of say, 19ft. Fineness ratio now 19/2.5=7.6. Looking good for a cruising tri. Are you also lengthening the amas? Moving their bows forward? I wonder: bigger sail, and tiny outboard?


                > Another thought on cheap tris is Bolger once did a design where the builder did the main hull and then used an old Hobie 16 for the amas, cross beams & rig. Had one of his sugar scoop bows. I think hull was around 4 feet wide and around 20 feet long (may have been longer) and could sleep four under its low decks in a pinch. Had a center cockpit. Interesting design, althought the bow gave some concerns for punching through the square waves we get in shallow waters around here.
                > Gary

                I heard about a Camper trimaran done with the Hobie bits. I didn't realise it went to centre cockpit and decked over accomodation. I thought it to be an open boat, and pointy up front. Well now, that's interesting.

                Graeme

                ~ ___/) ~~~
              • graeme19121984
                Doug, arguments go back and forth as to whether trimaran centre hulls ever plane or not. There s some big guns on either side of the debate. I go with the view
                Message 7 of 24 , Oct 5, 2009
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                  Doug,

                  arguments go back and forth as to whether trimaran centre hulls ever plane or not. There's some big guns on either side of the debate. I go with the view that for most intents and purposes they don't really plane. It's unlikely the centre hull ever lifts the others. With heeling under sail the windward hull and centre hull are jacked up as their weight is loaded onto the leeward hull. The centre hull waterline beam is reduced which increases its fineness. That's why tris can get away with a central hull fineness from down to about 6, whereas for catamarans it's about 10. That's partly because the loaded leeward hull decreases in fineness. The wind-loaded tri sheds wetted area, but the cat gains it. The tri centre hull is really still slicing the water in displacement mode.

                  I concede the possibility of a bit of planing going on. Is it really "planing" though if there's more than hydrodynamic forces lifting the hull (hydrostatic in the diplacement mode lee hull resisting aerodynamic in the rig)? OTOH could it be the case that if there is any hydrodynamic lift at all then that is "planing"?

                  Tris that have been designed to truly plane on their hulls (and that will mostly be on the lee one) have been fast. BUT they haven't been race winners, nor even good boats. They're not handy. They need the big wind - without it they're dogs - with wind comes waves - with waves comes punching - so how do they get up, then maintain the plane when there is wind? They have hulls that have comparitively very low drag at planing speed, which to a certain extent continues to reduce with more speed, but below planing speeds such hulls are comparitively very draggy. A planing power boat hull doesn't have to be so versatile.

                  Big fast [read $$$$$$$!] tris now go literally "all out" and plane on foils, eg http://www.ziltmagazine.com/video/nummer42-2009/hydroptere/hydroptere.html 55.5kts! If this is accepted, it has the world sailboat speed record. 61knots capsize. This French boat is a prototype for a larger one. Wow! (11ft hydrofoiling Moth dinghies have beeen clocked at 40kts!)


                  Graeme

                  ~ ___
                  ____/) ~ ~
                  ___
                  V ~ ~ ~



                  --- In Michalak@yahoogroups.com, Douglas Pollard <dougpol1@...> wrote:

                  > I guess what I was thinking when I wrote the previous post is. That the
                  > modern 30ft'ish trimarans I have seen have very narrow center hulls that
                  > widen out above the water line. They basically have a long narrow foot
                  > well in side the boat with bunks on either side. These extremely
                  > narrow center hulls also have very high hull speeds. But a small
                  > trimaran would seem to need a wide hull amidships to have any usable
                  > space. A wide hull would have to plane. I'm wondering if the bow would
                  > be able to climb on top the water and drop down on a plane at some
                  > speed. With the outer hulls not planing the main hull would have to lift
                  > them as well. AS they lift at the bow the hull in the water would get
                  > shorter so hull speed would go down. They would not likely plane with
                  > such a narrow none plaining hull shape. Would they then drag the
                  > center hull speed down. I don't pretend to know much about trimarans
                  > but these are kind of my what if's. I would like to hear some
                  > thinking on these musings. Doug
                  >
                • Peter
                  The discussion has involved trimarans but the subject line says catamarans. If your interest is in cats, here is an (apparently) home-built cat for sale; I
                  Message 8 of 24 , Oct 6, 2009
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                    The discussion has involved trimarans but the subject line says catamarans.

                    If your interest is in cats, here is an (apparently) home-built
                    cat for sale; I have seen her from the water on St. Andrews Bay
                    but have never been aboard.

                    http://www.sailingtexas.com/swharrampahi42100.html



                    For a cat of more diminutive proportions, what about
                    (2) of these hulls arranged as a cat?

                    http://homepages.paradise.net.nz/garyd/wa_apa.html




                    P. Beckford
                  • graeme19121984
                    Glen Tieman sailed the Pacific for years on a much cheaper ply Pahi 26 he built in the early 90 s. He s back out there again on a 38 Child of the Sea design
                    Message 9 of 24 , Oct 8, 2009
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                      Glen Tieman sailed the Pacific for years on a much cheaper ply Pahi 26 he built in the early 90's. He's back out there again on a 38' "Child of the Sea" design he reportedly built and launched in California for only $15k. WRC strip planked.

                      Graeme

                      ____/)__ ~ ~ ~

                      --- In Michalak@yahoogroups.com, "Peter" <boatman1959@...> wrote:
                      >
                      > The discussion has involved trimarans but the subject line says catamarans.
                      >
                      > If your interest is in cats, here is an (apparently) home-built
                      > cat for sale; I have seen her from the water on St. Andrews Bay
                      > but have never been aboard.
                      >
                      > http://www.sailingtexas.com/swharrampahi42100.html
                      >
                      >
                      >
                      > For a cat of more diminutive proportions, what about
                      > (2) of these hulls arranged as a cat?
                      >
                      > http://homepages.paradise.net.nz/garyd/wa_apa.html
                      >
                      >
                      >
                      >
                      > P. Beckford
                      >
                    • Peter
                      I would think enough Western red cedar to plank a 38 ft boat alone would cost $15,000.00 US I like the Wharram designs but feel the price of plans for even the
                      Message 10 of 24 , Oct 9, 2009
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                        I would think enough Western red cedar to plank a 38 ft boat alone
                        would cost $15,000.00 US


                        I like the Wharram designs but feel the price of plans for even the
                        smaller Tiki's is too high; otherwide I would have a plans-set for
                        the 21.



                        P. Beckford



                        --- In Michalak@yahoogroups.com, "graeme19121984" <graeme19121984@...> wrote:
                        >
                        >
                        >
                        > Glen Tieman sailed the Pacific for years on a much cheaper ply Pahi 26 he built in the early 90's. He's back out there again on a 38' "Child of the Sea" design he reportedly built and launched in California for only $15k. WRC strip planked.
                        >
                        > Graeme
                        >
                        > ____/)__ ~ ~ ~
                        >
                        > --- In Michalak@yahoogroups.com, "Peter" <boatman1959@> wrote:
                        > >
                        > > The discussion has involved trimarans but the subject line says catamarans.
                        > >
                        > > If your interest is in cats, here is an (apparently) home-built
                        > > cat for sale; I have seen her from the water on St. Andrews Bay
                        > > but have never been aboard.
                        > >
                        > > http://www.sailingtexas.com/swharrampahi42100.html
                        > >
                        > >
                        > >
                        > > For a cat of more diminutive proportions, what about
                        > > (2) of these hulls arranged as a cat?
                        > >
                        > > http://homepages.paradise.net.nz/garyd/wa_apa.html
                        > >
                        > >
                        > >
                        > >
                        > > P. Beckford
                        > >
                        >
                      • Mike John
                        There is always *Paulownia* which is a good Western Red Cedar substitute. Mike http://www.duckworksmagazine.com/r/indexes.htm ... -- Mike
                        Message 11 of 24 , Oct 9, 2009
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                          There is always *Paulownia* which is a good Western Red Cedar substitute.
                          Mike

                          http://www.duckworksmagazine.com/r/indexes.htm



                          On Sat, Oct 10, 2009 at 11:28 AM, Peter <boatman1959@...> wrote:

                          >
                          >
                          > I would think enough Western red cedar to plank a 38 ft boat alone
                          > would cost $15,000.00 US
                          >
                          > I like the Wharram designs but feel the price of plans for even the
                          > smaller Tiki's is too high; otherwide I would have a plans-set for
                          > the 21.
                          >
                          > P. Beckford
                          >
                          > --- In Michalak@yahoogroups.com <Michalak%40yahoogroups.com>,
                          > "graeme19121984" <graeme19121984@...> wrote:
                          > >
                          > >
                          > >
                          > > Glen Tieman sailed the Pacific for years on a much cheaper ply Pahi 26 he
                          > built in the early 90's. He's back out there again on a 38' "Child of the
                          > Sea" design he reportedly built and launched in California for only $15k.
                          > WRC strip planked.
                          > >
                          > > Graeme
                          > >
                          > > ____/)__ ~ ~ ~
                          > >
                          > > --- In Michalak@yahoogroups.com <Michalak%40yahoogroups.com>, "Peter"
                          > <boatman1959@> wrote:
                          > > >
                          > > > The discussion has involved trimarans but the subject line says
                          > catamarans.
                          > > >
                          > > > If your interest is in cats, here is an (apparently) home-built
                          > > > cat for sale; I have seen her from the water on St. Andrews Bay
                          > > > but have never been aboard.
                          > > >
                          > > > http://www.sailingtexas.com/swharrampahi42100.html
                          > > >
                          > > >
                          > > >
                          > > > For a cat of more diminutive proportions, what about
                          > > > (2) of these hulls arranged as a cat?
                          > > >
                          > > > http://homepages.paradise.net.nz/garyd/wa_apa.html
                          > > >
                          > > >
                          > > >
                          > > >
                          > > > P. Beckford
                          > > >
                          > >
                          >
                          >
                          >



                          --
                          Mike

                          http://www.duckworksmagazine.com/r/indexes.htm


                          [Non-text portions of this message have been removed]
                        • graeme19121984
                          I believe he got hold of fairly hefty planks, then cut, thicknessed, coved and tenoned the strips himself. A lot of extra work that way than just buying in the
                          Message 12 of 24 , Oct 10, 2009
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                            I believe he got hold of fairly hefty planks, then cut, thicknessed, coved and tenoned the strips himself. A lot of extra work that way than just buying in the production strips, I suppose? I think it took about three years to get to launch, and some of that fulltime. Not much cost to launch as comparitively minimalist fitout - the sail rig cost almost peanuts! Seems to have proven a good sea boat.

                            I imagine the accomodations, even the cokpit, to feel a little like being in Robbsboat after a time. Crouching. Kneeling. Lotusing (?). -- But well protected and comfy.

                            Graeme

                            ~~~ ___/)
                            ~~~
                            --- In Michalak@yahoogroups.com, "Peter" <boatman1959@...> wrote:
                            >
                            > I would think enough Western red cedar to plank a 38 ft boat alone
                            > would cost $15,000.00 US
                            >
                            >
                            > I like the Wharram designs but feel the price of plans for even the
                            > smaller Tiki's is too high; otherwide I would have a plans-set for
                            > the 21.
                            >
                            >
                            >
                            > P. Beckford
                          • graeme19121984
                            Yes, and cheaper already in strips, I believe. Graeme ~.~ ____/) ~.~
                            Message 13 of 24 , Oct 10, 2009
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                              Yes, and cheaper already in strips, I believe.

                              Graeme

                              ~.~
                              ____/) ~.~
                              ~~~~~

                              --- In Michalak@yahoogroups.com, Mike John <mikeduckboatman@...> wrote:
                              >
                              > There is always *Paulownia* which is a good Western Red Cedar substitute.
                              > Mike
                              >
                              > http://www.duckworksmagazine.com/r/indexes.htm
                              >
                              >
                              >
                              > On Sat, Oct 10, 2009 at 11:28 AM, Peter <boatman1959@...> wrote:
                              >
                              > >
                              > >
                              > > I would think enough Western red cedar to plank a 38 ft boat alone
                              > > would cost $15,000.00 US
                            • Peter
                              Have not heard of Paulownia. A quick check on the internet shows it to be lighter by a few pounds per cubic foot than WRC. I have never noticed it for sale
                              Message 14 of 24 , Oct 10, 2009
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                                Have not heard of Paulownia.

                                A quick check on the internet shows it to be
                                lighter by a few pounds per cubic foot than
                                WRC.

                                I have never noticed it for sale around here
                                in the midwest USA but then I was not looking
                                for it.



                                P. Beckford





                                --- In Michalak@yahoogroups.com, Mike John <mikeduckboatman@...> wrote:
                                >
                                > There is always *Paulownia* which is a good Western Red Cedar substitute.
                                > Mike
                                >
                              • Mike John
                                It has been around a long time but it is growing in boatbuilding. Trees grow fast to reach maturity in 8-10 years. China had it 2600 years ago. Good site
                                Message 15 of 24 , Oct 10, 2009
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                                  It has been around a long time but it is growing in boatbuilding. Trees grow
                                  fast to reach maturity in 8-10 years. China had it 2600 years ago. Good
                                  site http://www.paulowniatrees.com.au/
                                  <http://www.paulowniatrees.com.au/>Mike
                                  http://www.duckworksmagazine.com/r/indexes.htm
                                  <http://www.duckworksmagazine.com/r/indexes.htm>

                                  On Sun, Oct 11, 2009 at 12:20 PM, Peter <boatman1959@...> wrote:

                                  >
                                  >
                                  > Have not heard of Paulownia.
                                  >
                                  > A quick check on the internet shows it to be
                                  > lighter by a few pounds per cubic foot than
                                  > WRC.
                                  >
                                  > I have never noticed it for sale around here
                                  > in the midwest USA but then I was not looking
                                  > for it.
                                  >
                                  > P. Beckford
                                  >
                                  > --- In Michalak@yahoogroups.com <Michalak%40yahoogroups.com>, Mike John
                                  > <mikeduckboatman@...> wrote:
                                  > >
                                  > > There is always *Paulownia* which is a good Western Red Cedar substitute.
                                  > > Mike
                                  > >
                                  >
                                  >
                                  >



                                  --
                                  Mike

                                  http://www.duckworksmagazine.com/r/indexes.htm


                                  [Non-text portions of this message have been removed]
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