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Re: Motorsailers Revisted

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  • prairiedog2332
    Made a typo in the previous post. Of course the Twister is 16x6 350 lb.There are some photos of a Twister here.
    Message 1 of 11 , Mar 5 11:03 AM
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      Made a typo in the previous post. Of course the Twister is 16x6 350
      lb.There are some photos of a Twister here.
      http://groups.yahoo.com/group/Michalak/photos/album/396809197/pic/list

      Couple things that caught my eye, With the broad transom there is room
      to mount the motor right on the centre line and off-set the rudder
      which I prefer. But the corners and bottom of the transom are almost
      dragging even with the bottom rocker shown in the plans and Owen's wife
      sitting forward on the bridge deck. Twister will handle up to a 5-6 hp
      4-stroke and these are not light and act as a lever back there on the
      stern. So chances are the corner of the transom is going to drag anyway
      under sail unless you use a smaller, lighter OB. And probably the
      helmsperson sitting forward more on the side seat in the cockpit and
      using a tiller extension. Owen has short removable side seats in his
      build - between the bridge deck and the stern flotation chamber - a nice
      mod.

      Bolger mentions in an article about his Brick design: "It's possible
      that running the bottom straight back to a perfectly rectangular stern
      would increase capacity more than resistance." (That is with no motor -
      just the helms person) So with less rocker you get more carrying
      capacity for the heavier motor plus it runs more level under power.

      But this can be overdone, too flat a run aft not only causes the transom
      corners to drag under sail but also pushes the bow down from the force
      of the sail and affects the steerage. Not so much with a pram bow but
      more so with a pointy bow. So am wondering if a bit of compromise with
      maybe half as much rocker than shown on the plans might help off-set the
      motor leverage?

      Another thing that occurs to me is that this is an unballasted design.
      So maybe going with a somewhat smaller low aspect sail area is a good
      idea and try to sail with the boat staying upright which the flat bottom
      helps in that regard. Jim mentions it is not a very fast sail boat
      anyway and the main purpose is to get some sailing experience and the
      chance to shut off the motor and enjoy some leisurely sailing or
      trolling.

      It does demonstrate the trade-off challenges required when designing a
      motorsailor. In my case leaning more towards the motoring ability in
      having to deal with going upstream on a river.

      Nels


      --- In Michalak@yahoogroups.com, "prairiedog2332" <nelsarv@...> wrote:
      >
      > I have Trilars plans.
      > Twister meets my criteria regarding size and weight (16x16 350 lbs.)




      [Non-text portions of this message have been removed]
    • John
      Maybe making the stern just a little wider will do the trick. Looking at the plan you could add 2 of width to the transom and maybe 1 to the aft cockpit
      Message 2 of 11 , Mar 5 11:43 AM
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        Maybe making the stern just a little wider will do the trick. Looking at the plan you could add 2" of width to the transom and maybe 1" to the aft cockpit bulkhead. Keeping the same hull flare your change would not change the looks of the boat. See how many square inches of additional area it will give you.

        In hind-sight the motor well of Hapscut could of been about 2" wider at the bottom. (1" either side of centerline)

        I can get 6.5mph on a fully loaded Hapscut (1000lbs) with a Nissan 4hp, 4 stroke outboard. A 3.5hp would push it also and save about 16 pounds of weight on the transom.

        I bet the least amount of trouble would be to widen the stern and not change the rocker. I recently got into some big waves and high winds and was glad I could sit at the transom and keep the bow out of the backside of the waves we were overtaking. If the rocker had been flattered I would of just plowed into the waves.

        --- In Michalak@yahoogroups.com, "prairiedog2332" <nelsarv@...> wrote:
        >
        > Made a typo in the previous post. Of course the Twister is 16x6 350
        > lb.There are some photos of a Twister here.
        > http://groups.yahoo.com/group/Michalak/photos/album/396809197/pic/list
        >
        > Couple things that caught my eye, With the broad transom there is room
        > to mount the motor right on the centre line and off-set the rudder
        > which I prefer. But the corners and bottom of the transom are almost
        > dragging even with the bottom rocker shown in the plans and Owen's wife
        > sitting forward on the bridge deck. Twister will handle up to a 5-6 hp
        > 4-stroke and these are not light and act as a lever back there on the
        > stern. So chances are the corner of the transom is going to drag anyway
        > under sail unless you use a smaller, lighter OB. And probably the
        > helmsperson sitting forward more on the side seat in the cockpit and
        > using a tiller extension. Owen has short removable side seats in his
        > build - between the bridge deck and the stern flotation chamber - a nice
        > mod.
        >
        > Bolger mentions in an article about his Brick design: "It's possible
        > that running the bottom straight back to a perfectly rectangular stern
        > would increase capacity more than resistance." (That is with no motor -
        > just the helms person) So with less rocker you get more carrying
        > capacity for the heavier motor plus it runs more level under power.
        >
        > But this can be overdone, too flat a run aft not only causes the transom
        > corners to drag under sail but also pushes the bow down from the force
        > of the sail and affects the steerage. Not so much with a pram bow but
        > more so with a pointy bow. So am wondering if a bit of compromise with
        > maybe half as much rocker than shown on the plans might help off-set the
        > motor leverage?
        >
        > Another thing that occurs to me is that this is an unballasted design.
        > So maybe going with a somewhat smaller low aspect sail area is a good
        > idea and try to sail with the boat staying upright which the flat bottom
        > helps in that regard. Jim mentions it is not a very fast sail boat
        > anyway and the main purpose is to get some sailing experience and the
        > chance to shut off the motor and enjoy some leisurely sailing or
        > trolling.
        >
        > It does demonstrate the trade-off challenges required when designing a
        > motorsailor. In my case leaning more towards the motoring ability in
        > having to deal with going upstream on a river.
        >
        > Nels
        >
        >
        > --- In Michalak@yahoogroups.com, "prairiedog2332" <nelsarv@> wrote:
        > >
        > > I have Trilars plans.
        > > Twister meets my criteria regarding size and weight (16x16 350 lbs.)
        >
        >
        >
        >
        > [Non-text portions of this message have been removed]
        >
      • prairiedog2332
        Thanks John for sharing your experience! 6.5 mph would really do the job! The thing is I think Hapscut has about 4 ft. more waterline length with the motor
        Message 3 of 11 , Mar 5 2:09 PM
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          Thanks John for sharing your experience!


          6.5 mph would really do the job! The thing is I think Hapscut has about
          4 ft. more waterline length with the motor well you added? That would
          make for a very easily driven displacement hull. Some of the currents I
          would have to deal with are in the order of 5 mph or so and Jim was
          kind to share that 5 mph is about the best you can get with the Twister
          design. I have a 5 hp Honda 4-stroke. Adding power would cause the
          stern to sink and dig a bigger hole in the water and not accomplish
          anything. Flattening the run aft would spoil the sailing performance -
          so he did not like that idea.


          My trailer and my building space restrict me to 16 ft at most. A Hapscut
          shortened is an idea but may end up with same same hull speed as Twister
          maybe. So thinking of a way to prevent the stern from sinking and
          digging a bigger hole somehow as being a possibility even if the
          sailing ability suffers.


          There was an idea suggested about adding a flat shallow box keel faired
          in to the after section of a sailing scow to improve motoring ability.
          It is in the files section in pdf format. Not sure if that idea was ever
          tried.

          http://groups.yahoo.com/group/Michalak/files/Sailing%20scow%20to%20motor\
          %20scow/

          Another thought is to add adjustable flaps to the stern and raise them
          and the motor when sailing. The idea is to get the stern to stay high
          enough to get into a semi-plane mode yet adding enough flotation to help
          prevent the transom corners from dragging and slow it in sailing mode.
          "Semi-planing" is always a subject of much conjecture. Jim mentioned
          that many photos showing a hull planing are not really planing.

          Can't tell from looking at the plans online - but looking at the photos
          - I think Twister's transom is as wide as Hapcuts? Hapscut has higher
          sides and wider at the top with more flare but seems to narrow down more
          towards the stern? But will look at that option for sure! Hoping this
          adds some info for the group and sorry for being so wordy. Will leave
          off for now. Am finding Yahoo very unfriendly when trying to post.

          Nels



          --- In Michalak@yahoogroups.com, "John" <goodman_clan@...> wrote:
          >
          > Maybe making the stern just a little wider will do the trick. Looking
          at the plan you could add 2" of width to the transom and maybe 1" to the
          aft cockpit bulkhead. Keeping the same hull flare your change would not
          change the looks of the boat. See how many square inches of additional
          area it will give you.
          >
          > In hind-sight the motor well of Hapscut could of been about 2" wider
          at the bottom. (1" either side of centerline)
          >
          > I can get 6.5mph on a fully loaded Hapscut (1000lbs) with a Nissan
          4hp, 4 stroke outboard. A 3.5hp would push it also and save about 16
          pounds of weight on the transom.
          >
          > I bet the least amount of trouble would be to widen the stern and not
          change the rocker. I recently got into some big waves and high winds and
          was glad I could sit at the transom and keep the bow out of the backside
          of the waves we were overtaking. If the rocker had been flattered I
          would of just plowed into the waves.
          >




          [Non-text portions of this message have been removed]
        • John
          Here is some information I shared with Jim concerning Hapscut. The bottom of my motor well transom measures 34 wide including the chine logs. It should of
          Message 4 of 11 , Mar 6 7:14 AM
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            Here is some information I shared with Jim concerning Hapscut.

            The bottom of my motor well transom measures 34" wide including the chine logs. It should of been at least 35"-36" to make the curve along the chine log more smooth and attractive. (I notice it. Others don't)

            Hapscut when fully loaded has an "at rest" water line of 15'-1" and a draft of 2.75".

            Here is the link to a video of my motoring into the wind with a slight chop: http://www.youtube.com/watch?v=4cpX4eaqS6M

            Having some type of trim tab on the transom sounds like a complicated mess. I built a model of Hapscut with a "sugar scoop" transom that can be seen in the Photo Album called "Hapscut". I thought it might work better than an engine well. The model showed me it would not work.

            Hapscut was the biggest boat I could build and store in my garage so I understand the limitations of available space. Twister should work well for you.
          • prairiedog2332
            Thanks again John, Hapscut is one amazing design and you and family have tested out the prototype very thoroughly and am quite certain Jim agrees with the
            Message 5 of 11 , Mar 6 9:22 AM
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              Thanks again John,

              Hapscut is one amazing design and you and family have tested out the
              prototype very thoroughly and am quite certain Jim agrees with the added
              transom width. The video was great showing what it can do under power at
              less than half throttle with a 4 hp Tohatsu 4-stroke. Obviously the
              15' waterline really helps and so does the bit narrower bottom with more
              flare than Jim has done previously. Less pounding with that light draft
              and getting the balance just right. Then just quartering a bit into the
              bigger waves as you already mentioned.


              I reviewed several of Jim's designs especially the earlier AF series.
              They had narrow raised transoms - with lots of rocker - but back then
              most people only had 2-3.5 hp 2-strokes which are less than half the
              weight of today's 4-strokes. Of course the original sharpies had no
              outboard motors so the smaller capacity back there was not a problem.


              His only "true" motorsailer was the Petesboat.


              http://www.duckworksbbs.com/plans/jim/petesboat/index.htm


              Based on Jewelbox.


              http://www.duckworksbbs.com/plans/jim/jewelbox/index.htm


              Unfortunately neither link shows the underwater rocker profiles but
              obviously the Petesboat - meant to plane - had a flatter run aft but
              not as flat as say the AF4 as it was meant to sail as well as motor.
              Pretty sure Jewelbox has more curvature aft than Hapscut. But the thing
              Jim mentioned that caught my attention was he widened the transom on
              Petesboat:-)

              So I think I should build a scale model of Twister and see how wide I
              could go and still keep a smooth curve to the topsides. So my conclusion
              is that if planning to use a 4-stroke OB of 4+ hp a person might
              consider looking at designs with a wider transom than some of his
              earlier ones. This also allows one to mount the heavier motor on the
              centreline and still have space for and off-set rudder. If you want to
              use a lighter motor - like the Honda 2 then fine to off-set the motor
              and go with an older design.

              Nels



              --- In Michalak@yahoogroups.com, "John" <goodman_clan@...> wrote:
              >
              > Here is some information I shared with Jim concerning Hapscut.
              >
              > The bottom of my motor well transom measures 34" wide including the
              chine logs. It should of been at least 35"-36" to make the curve along
              the chine log more smooth and attractive. (I notice it. Others don't)
              >
              > Hapscut when fully loaded has an "at rest" water line of 15'-1" and a
              draft of 2.75".
              >
              > Here is the link to a video of my motoring into the wind with a slight
              chop: http://www.youtube.com/watch?v=4cpX4eaqS6M
              >
              > Having some type of trim tab on the transom sounds like a complicated
              mess. I built a model of Hapscut with a "sugar scoop" transom that can
              be seen in the Photo Album called "Hapscut". I thought it might work
              better than an engine well. The model showed me it would not work.
              >
              > Hapscut was the biggest boat I could build and store in my garage so I
              understand the limitations of available space. Twister should work well
              for you.
              >



              [Non-text portions of this message have been removed]
            • Joseph Stromski
              Frolic2 might be considered a motorsailer also. From plan description: I intended this to be a multi skiff sort of boat with rowing and motoring abilities.
              Message 6 of 11 , Mar 6 9:44 AM
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                Frolic2 might be considered a motorsailer also. From plan description:
                "I intended this to be a multi skiff sort of boat with rowing and motoring
                abilities. You can't row a boat of this size in any wind or waves but in a calm
                you can travel far if you have patience. I didn't fool around with a gadget
                motor mount - I put the motor well right in the middle and offset the rudder
                instead of the other way around. This worked out very well on the high
                powered Petesboat. "

                Best,
                Joe





                ________________________________
                From: prairiedog2332 <nelsarv@...>
                To: Michalak@yahoogroups.com
                Sent: Wed, March 6, 2013 11:22:19 AM
                Subject: [Michalak] Re: Motorsailers Revisted


                Thanks again John,

                Hapscut is one amazing design and you and family have tested out the
                prototype very thoroughly and am quite certain Jim agrees with the added
                transom width. The video was great showing what it can do under power at
                less than half throttle with a 4 hp Tohatsu 4-stroke. Obviously the
                15' waterline really helps and so does the bit narrower bottom with more
                flare than Jim has done previously. Less pounding with that light draft
                and getting the balance just right. Then just quartering a bit into the
                bigger waves as you already mentioned.

                I reviewed several of Jim's designs especially the earlier AF series.
                They had narrow raised transoms - with lots of rocker - but back then
                most people only had 2-3.5 hp 2-strokes which are less than half the
                weight of today's 4-strokes. Of course the original sharpies had no
                outboard motors so the smaller capacity back there was not a problem.

                His only "true" motorsailer was the Petesboat.

                http://www.duckworksbbs.com/plans/jim/petesboat/index.htm

                Based on Jewelbox.

                http://www.duckworksbbs.com/plans/jim/jewelbox/index.htm

                Unfortunately neither link shows the underwater rocker profiles but
                obviously the Petesboat - meant to plane - had a flatter run aft but
                not as flat as say the AF4 as it was meant to sail as well as motor.
                Pretty sure Jewelbox has more curvature aft than Hapscut. But the thing
                Jim mentioned that caught my attention was he widened the transom on
                Petesboat:-)

                So I think I should build a scale model of Twister and see how wide I
                could go and still keep a smooth curve to the topsides. So my conclusion
                is that if planning to use a 4-stroke OB of 4+ hp a person might
                consider looking at designs with a wider transom than some of his
                earlier ones. This also allows one to mount the heavier motor on the
                centreline and still have space for and off-set rudder. If you want to
                use a lighter motor - like the Honda 2 then fine to off-set the motor
                and go with an older design.

                Nels

                --- In Michalak@yahoogroups.com, "John" wrote:
                >
                > Here is some information I shared with Jim concerning Hapscut.
                >
                > The bottom of my motor well transom measures 34" wide including the
                chine logs. It should of been at least 35"-36" to make the curve along
                the chine log more smooth and attractive. (I notice it. Others don't)
                >
                > Hapscut when fully loaded has an "at rest" water line of 15'-1" and a
                draft of 2.75".
                >
                > Here is the link to a video of my motoring into the wind with a slight
                chop: http://www.youtube.com/watch?v=4cpX4eaqS6M
                >
                > Having some type of trim tab on the transom sounds like a complicated
                mess. I built a model of Hapscut with a "sugar scoop" transom that can
                be seen in the Photo Album called "Hapscut". I thought it might work
                better than an engine well. The model showed me it would not work.
                >
                > Hapscut was the biggest boat I could build and store in my garage so I
                understand the limitations of available space. Twister should work well
                for you.
                >

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




                [Non-text portions of this message have been removed]
              • prairiedog2332
                Absolutely agree. And I hear Caroline would qualify as would Fatcat2 that is shown on the plans site as a Power/Sail design. I like the idea of the flat
                Message 7 of 11 , Mar 6 10:13 AM
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                  Absolutely agree. And I hear Caroline would qualify as would Fatcat2
                  that is shown on the plans site as a Power/Sail design.


                  I like the idea of the flat bottom aft on Twister to perhaps give a bit
                  more weight capacity for a 5 hp 4-stroke over the multi-chine designs
                  back there in the stern? Plus the length matches my trailer and building
                  shed better. I guess the decision has to do with how you plan to use the
                  boat most of the time?


                  The above designs are certainly superior in sailing performance and
                  seaworthiness whereas I live on the river bank.

                  Nels



                  --- In Michalak@yahoogroups.com, Joseph Stromski <j.stromski@...> wrote:
                  >
                  > Frolic2 might be considered a motorsailer also. From plan description:
                  > "I intended this to be a multi skiff sort of boat with rowing and
                  motoring
                  > abilities. You can't row a boat of this size in any wind or waves but
                  in a calm
                  > you can travel far if you have patience. I didn't fool around with a
                  gadget
                  > motor mount - I put the motor well right in the middle and offset the
                  rudder
                  > instead of the other way around. This worked out very well on the high
                  > powered Petesboat. "
                  >
                  > Best,
                  > Joe
                  >




                  [Non-text portions of this message have been removed]
                • prairiedog2332
                  After reflecting on this subject for some time it suddenly occurred to me that a design that has the water ballast option is the best way to go. DOH!
                  Message 8 of 11 , Mar 11 6:59 PM
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                    After reflecting on this subject for some time it suddenly occurred to
                    me that a design that has the water ballast option is the best way to
                    go. DOH!

                    Traditionally motorsailers have a small sail plan to compensate for
                    their lack of ballast when in motoring mode, which would mean dragging
                    weight that just burns more gas. So that brought me back the ballast
                    bags like used on wake boats to increase the size of the wake. So might
                    be an idea with Twister, Fatcat2, or other designs that motor well but
                    don't have water ballast as a part of the overall design to hold up a
                    larger sailplan when in sailing mode. So a ballast bag under the bridge
                    deck that is easily filled when wanting to sail and then emptied when
                    wanting to motor or to sleep to allow the foot space under the bridge
                    deck might be an option and worth the investment. Located amidships
                    might help keep the transom from dragging under sail and the crew can
                    relax in the upwind cockpit seat and keep the bow up going downwind. Of
                    course an option to consider after trying with no ballast as designed.


                    http://www.wakemakers.com/wakeboard-ballast-bags?gclid=CITMj-OE9rUCFVSVM\
                    godiloAUw


                    This might do the job for $60


                    http://www.wakemakers.com/straight-line-big-bag-150-ballast-bag.html


                    Ideally add the cost of a pump for about another $100

                    http://www.wakemakers.com/launch-pad-sumo-pump.html


                    Nels


                    --- In Michalak@yahoogroups.com, "prairiedog2332" <nelsarv@...> wrote:
                    >
                    > Absolutely agree. And I hear Caroline would qualify as would Fatcat2
                    > that is shown on the plans site as a Power/Sail design.
                    >




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