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Re: Pop Pop 16' canoe

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  • sydneygreenestreet
    Interesting, you refering to the Commonwealth ... How do I attach an MP3 file of Vera Lyn Singing There ll always be an England ? So a longer boat of similar
    Message 1 of 15 , Aug 1, 2009
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      Interesting, you refering to the "Commonwealth"... How do I attach an MP3 file of Vera Lyn Singing "There'll always be an England"?
      So a longer boat of similar beam to a shorter boat will require less power to get it to go faster that the shorter boat. ie a boat 12' by 4' will need more power that a 20' x 4' boat to travel at the same speed ergo a 16' x 3' canoe (you call them Indian canoes made famous by Nelson Eddy and Jannete MacDonald to me they are classed as yes you guessed it Empire Canoes)will need less power to travel at the same speed as an 8' x 4'6" snub nosed dinghy....

      Don't worry I'll not be disuaded by people who prefer drinking coffee to haveing proper tea....

      We went through the horse on treadmill era here to drive ferries but steam soon replaced them though we still have horse drawn trams (trolleys) on the Granite Island service (google it), very interesting technically at the points at the loops dont have blades, the cars are steered by the horse pulling them to the left. Which brings up another question, how many people remember the exact location of a tram stop 30 years after the tracks have been covered with asphalt?
      Now Gracie (my wonder dog, constant companion and holder of her own rail, tram, ferry and bus pass) does have the webbed feet typical of water loving dogs and when we go swimming she tows me along on the leash quite well but as for putting her on a treadmill, I think the RSPCA would go beresk...

      The object here I think is to flash boil as much water as quickly as possible so maybe the diapragm is really only good for smaller applications. I have 6m length of aluminium tube, I'm gonna have a fart around with it and a huge LPG burner and asseseseseses the results before I start on the copper... one other consideration is the vibration causing the copper to workharden and fail. It does in full size marine engineering practise something else to consider I guess.
    • KENNETH TAIT SR.
      Sydney, I sure do enjoy reading what have written, and discussed. I gather that you are on the other side of the pond, so to speak. My wife had an Irish
      Message 2 of 15 , Aug 1, 2009
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        Sydney,

        I sure do enjoy reading what have written, and discussed.

        I gather that you are on the other side of the pond, so to speak. My wife had an Irish grandfather that came across the pond during the potato faming. He used to tell us some funny stories of his antics when he was a boy back there. He told us of the donkey and dog carts that I guess were plentiful back then.

        Well as usual I got off the subject I was going to mention.  Many years ago I read about a ferry that used the car that was crossing the river for power. It was a flat deck barge on a cable that had a pair of rollers where the wheels rested on the deck. when the car was loaded they parked the rear wheels on the two rollers like on a dyno and they were used to power the ferry. I don't remember if it was hooked to a winch or to a propeller, or paddle wheel. Thought you might be interested in that little tidbit.

                                 Papa Tait Seekonk,Ma.




        --- On Sat, 8/1/09, sydneygreenestreet <sydneygreenestreet@...> wrote:

        From: sydneygreenestreet <sydneygreenestreet@...>
        Subject: [pop-pop-steamboats] Re: Pop Pop 16' canoe
        To: pop-pop-steamboats@yahoogroups.com
        Date: Saturday, August 1, 2009, 7:23 PM

         

        Interesting, you refering to the "Commonwealth" ... How do I attach an MP3 file of Vera Lyn Singing "There'll always be an England"?
        So a longer boat of similar beam to a shorter boat will require less power to get it to go faster that the shorter boat. ie a boat 12' by 4' will need more power that a 20' x 4' boat to travel at the same speed ergo a 16' x 3' canoe (you call them Indian canoes made famous by Nelson Eddy and Jannete MacDonald to me they are classed as yes you guessed it Empire Canoes)will need less power to travel at the same speed as an 8' x 4'6" snub nosed dinghy....

        Don't worry I'll not be disuaded by people who prefer drinking coffee to haveing proper tea....

        We went through the horse on treadmill era here to drive ferries but steam soon replaced them though we still have horse drawn trams (trolleys) on the Granite Island service (google it), very interesting technically at the points at the loops dont have blades, the cars are steered by the horse pulling them to the left. Which brings up another question, how many people remember the exact location of a tram stop 30 years after the tracks have been covered with asphalt?
        Now Gracie (my wonder dog, constant companion and holder of her own rail, tram, ferry and bus pass) does have the webbed feet typical of water loving dogs and when we go swimming she tows me along on the leash quite well but as for putting her on a treadmill, I think the RSPCA would go beresk...

        The object here I think is to flash boil as much water as quickly as possible so maybe the diapragm is really only good for smaller applications. I have 6m length of aluminium tube, I'm gonna have a fart around with it and a huge LPG burner and asseseseseses the results before I start on the copper... one other consideration is the vibration causing the copper to workharden and fail. It does in full size marine engineering practise something else to consider I guess.


      • Donald Qualls
        ... There are two factors at work here (maybe three). First, fineness ratio; generally, for a given displacement, the finer hull (longer and narrower) will
        Message 3 of 15 , Aug 2, 2009
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          sydneygreenestreet wrote:
          > So a
          > longer boat of similar beam to a shorter boat will require less power
          > to get it to go faster that the shorter boat. ie a boat 12' by 4'
          > will need more power that a 20' x 4' boat to travel at the same speed
          > ergo a 16' x 3' canoe (you call them Indian canoes made famous by
          > Nelson Eddy and Jannete MacDonald to me they are classed as yes you
          > guessed it Empire Canoes)will need less power to travel at the same
          > speed as an 8' x 4'6" snub nosed dinghy....
          >

          There are two factors at work here (maybe three). First, fineness
          ratio; generally, for a given displacement, the "finer" hull (longer and
          narrower) will require less power at any speed than the less fine,
          though refinements in the shape beneath the waterline can reduce power
          requirement, up to a point, for any fineness.

          Second, hull speed; there's a speed, for any given waterline length of
          displacement hull (that is, a hull supported only by buoyancy, not by
          dynamic forces), above which the power requirement for greater speed
          increases very sharply, and that speed is the one at which the trough
          following the bow wave just reaches the stern (since the speed of common
          waves in water is fixed, this comes to a specific speed for any given
          hull length). Hull speed is why the aircraft carrier is typically the
          fastest ship in a fleet, even though destroyers have much higher power
          to weight ratio; a modern supercarrier will have a hull speed in excess
          of forty knots, while a destroyer is limited to not much over twenty,
          and a tender (basically a miniature tanker, not much bigger than an
          oceangoing tug) may have to plug along at twelve to fifteen. A transom
          stern can help here, because it provides an effective lengthening of the
          waterline at speed when the water takes time to fill in behind the boat.

          The potential third factor is the one mentioned relative to hull speed:
          if a hull planes, that is, is partly supported by dynamic forces, it can
          go faster than hull speed without the precipitous increase in required
          power. This is why a tug with five thousand horsepower on tap can still
          only churn away at ten or twelve knots, while a runabout with as little
          as fifty horsepower can manage thirty-five (and with a couple hundred
          can go sixty): the runabout is using hydrodynamic lift to climb over the
          bow wave instead of wasting horsepower just building it higher and higher.

          This is applicable to pop-pop boats because every one I've seen is a
          displacement hull; even if the hull is correctly shaped to plane,
          pop-pop motors don't have enough power to climb up onto the bow wave, so
          none of them will go faster than hull speed -- which is pretty slow for
          a boat with a waterline length of, at most, a couple feet.

          For the application of a people (and dog) carrying canoe, it's unlikely
          an reasonably sized power plant will push a canoe significantly faster
          than a couple strong paddlers. Beyond that, wind forces on the hull's
          freeboard can be high enough to upset a paddler (I recall it being quite
          difficult to paddle upwind with a single person in the stern, because
          the available steering force was barely able to overcome the weathervane
          effect) and are likely to swamp the thrust available from even a fairly
          large pop-pop. On the other hand, if you have a canoe to experiment on,
          and the tubing and burner to play with, the worst you'll likely do is
          set fire to the canoe, sink an open bottle of LPG (which will pop up
          again when it gets sufficiently empty), and have to swim for land with
          your water dog towing you...

          --
          If, through hard work and perseverance, you finally get what you want,
          it's probably a sign you weren't dreaming big enough.

          Donald Qualls, aka The Silent Observer http://silent1.home.netcom.com

          Opinions expressed are my own -- take them for what they're worth
          and don't expect them to be perfect.
        • Jean-Yves Renaud
          Additional comments to message #1632 and 1634 from Sydney and Donald. 1°) The speed of a boat is stable when the hydrodynamic resistance is equal to the
          Message 4 of 15 , Aug 2, 2009
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            Additional comments to message #1632 and 1634 from Sydney and Donald.
            1°) The speed of a boat is stable when the hydrodynamic resistance is equal to the propulsive thrust. The hydrodynamic resistance is the sum of frictional resistance, wave resistance, and air resistance.
            The frictional resistance and air resistance evolve with the square of the boat velocity.
            The wave resistance is something much more complicated. For light displacement boats, when planning conditions are met it can decrease (and then increase again with the boat velocity). Unlikely to decrease for a canoe due to the shape of the hull.
            Whatever, pop-pop propulsive power is so minute that there is no chance of planning of a canoe.

            2°) To get the same thrust, 2 (or more) small engines are preferable to a big one because multiple engines are lighter and smaller, and because they develop a higher jet speed, which means a possible higher boat speed.
            Go to www.eclecticspace.net (it is not a commercial site), click on "pop-pop", then on the English flag, then on "To know more…" and scroll down to open the 3rd document from the bottom of the list: It is entitled "Engine/hull adaptation". Look at the graph at the end of this document. It expresses clearly the limits of pop-pop propulsion.


            --- In pop-pop-steamboats@yahoogroups.com, Donald Qualls <silent1@...> wrote:
            >
            > sydneygreenestreet wrote:
            > > So a
            > > longer boat of similar beam to a shorter boat will require less power
            > > to get it to go faster that the shorter boat. ie a boat 12' by 4'
            > > will need more power that a 20' x 4' boat to travel at the same speed
            > > ergo a 16' x 3' canoe (you call them Indian canoes made famous by
            > > Nelson Eddy and Jannete MacDonald to me they are classed as yes you
            > > guessed it Empire Canoes)will need less power to travel at the same
            > > speed as an 8' x 4'6" snub nosed dinghy....
            > >
            >
            > There are two factors at work here (maybe three). First, fineness
            > ratio; generally, for a given displacement, the "finer" hull (longer and
            > narrower) will require less power at any speed than the less fine,
            > though refinements in the shape beneath the waterline can reduce power
            > requirement, up to a point, for any fineness.
            >
            > Second, hull speed; there's a speed, for any given waterline length of
            > displacement hull (that is, a hull supported only by buoyancy, not by
            > dynamic forces), above which the power requirement for greater speed
            > increases very sharply, and that speed is the one at which the trough
            > following the bow wave just reaches the stern (since the speed of common
            > waves in water is fixed, this comes to a specific speed for any given
            > hull length). Hull speed is why the aircraft carrier is typically the
            > fastest ship in a fleet, even though destroyers have much higher power
            > to weight ratio; a modern supercarrier will have a hull speed in excess
            > of forty knots, while a destroyer is limited to not much over twenty,
            > and a tender (basically a miniature tanker, not much bigger than an
            > oceangoing tug) may have to plug along at twelve to fifteen. A transom
            > stern can help here, because it provides an effective lengthening of the
            > waterline at speed when the water takes time to fill in behind the boat.
            >
            > The potential third factor is the one mentioned relative to hull speed:
            > if a hull planes, that is, is partly supported by dynamic forces, it can
            > go faster than hull speed without the precipitous increase in required
            > power. This is why a tug with five thousand horsepower on tap can still
            > only churn away at ten or twelve knots, while a runabout with as little
            > as fifty horsepower can manage thirty-five (and with a couple hundred
            > can go sixty): the runabout is using hydrodynamic lift to climb over the
            > bow wave instead of wasting horsepower just building it higher and higher.
            >
            > This is applicable to pop-pop boats because every one I've seen is a
            > displacement hull; even if the hull is correctly shaped to plane,
            > pop-pop motors don't have enough power to climb up onto the bow wave, so
            > none of them will go faster than hull speed -- which is pretty slow for
            > a boat with a waterline length of, at most, a couple feet.
            >
            > For the application of a people (and dog) carrying canoe, it's unlikely
            > an reasonably sized power plant will push a canoe significantly faster
            > than a couple strong paddlers. Beyond that, wind forces on the hull's
            > freeboard can be high enough to upset a paddler (I recall it being quite
            > difficult to paddle upwind with a single person in the stern, because
            > the available steering force was barely able to overcome the weathervane
            > effect) and are likely to swamp the thrust available from even a fairly
            > large pop-pop. On the other hand, if you have a canoe to experiment on,
            > and the tubing and burner to play with, the worst you'll likely do is
            > set fire to the canoe, sink an open bottle of LPG (which will pop up
            > again when it gets sufficiently empty), and have to swim for land with
            > your water dog towing you...
            >
            > --
            > If, through hard work and perseverance, you finally get what you want,
            > it's probably a sign you weren't dreaming big enough.
            >
            > Donald Qualls, aka The Silent Observer http://silent1.home.netcom.com
            >
            > Opinions expressed are my own -- take them for what they're worth
            > and don't expect them to be perfect.
            >
          • sydneygreenestreet
            No one has mentioned hull Squat the phenomenom that occurs when traveling at speed in shallow water.... Seriously I don t expect speed in excess of around 2
            Message 5 of 15 , Aug 4, 2009
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              No one has mentioned "hull Squat" the phenomenom that occurs when traveling at speed in shallow water....
              Seriously I don't expect speed in excess of around 2 - 3 knots, serious paddlers can get considerably faster than this....Canoes are about as fine as you can get and move efficiently with little effort, just as any Canadian....
            • David Halfpenny
              ... From: sydneygreenestreet ... I learned a lot about canoes one day on the Cam. I was coxing (steering) a racing eight
              Message 6 of 15 , Aug 4, 2009
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                --------------------------------------------------
                From: "sydneygreenestreet" <sydneygreenestreet@...>

                > No one has mentioned "hull Squat" the phenomenom that occurs when
                > traveling at speed in shallow water....
                > Seriously I don't expect speed in excess of around 2 - 3 knots, serious
                > paddlers can get considerably faster than this....Canoes are about as
                > fine as you can get and move efficiently with little effort, just as any
                > Canadian....
                >
                I learned a lot about canoes one day on the Cam.

                I was coxing (steering) a racing eight parked at the bank, and past came
                two big red-faced lads paddling furiously in a double canoe, throwing up a
                mighty wake. Behind them was a slight young schoolboy on a scull boat (two
                oars). He was waiting courteously behind them, just touching his blades
                lightly in the water a couple of times a minute to keep up with the canoe.

                OK, I can handle a kayak in choppy water, and if I were hunting beaver in
                the northern territories I'd take the canoe every time, but the contrast in
                mechanical efficiency was staggering! Rowing coaches use bicycles because
                they have to to keep in sight of the crew.

                David 1/2d
              • Donald Qualls
                ... Assuming the boats were similar in length, this is about what you d expect -- the finer scull requires a little less power at any speed below hull speed,
                Message 7 of 15 , Aug 4, 2009
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                  David Halfpenny wrote:
                  > I learned a lot about canoes one day on the Cam.
                  >
                  > I was coxing (steering) a racing eight parked at the bank, and past came
                  > two big red-faced lads paddling furiously in a double canoe, throwing up a
                  > mighty wake. Behind them was a slight young schoolboy on a scull boat (two
                  > oars). He was waiting courteously behind them, just touching his blades
                  > lightly in the water a couple of times a minute to keep up with the canoe.

                  Assuming the boats were similar in length, this is about what you'd
                  expect -- the finer scull requires a little less power at any speed
                  below hull speed, but any attempt to exceed hull speed will soak up a
                  tremendous amount of power. Compounding this is the fact that a common
                  sliding seat single scull is several times more efficient in converting
                  muscle power into forward motion than a canoe with conventional paddles
                  (so is a kayak, come to that) -- that is, for a given amount of required
                  power, less effort is demanded of the rower than of canoe paddlers.

                  --
                  If, through hard work and perseverance, you finally get what you want,
                  it's probably a sign you weren't dreaming big enough.

                  Donald Qualls, aka The Silent Observer http://silent1.home.netcom.com

                  Opinions expressed are my own -- take them for what they're worth
                  and don't expect them to be perfect.
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