We do not have any wind measuring equipment on board, so relying upon wind forecast and what we see. I guess 8m/s was average and gusts 10-11m/s.

Doug Haines [doha720@yahoo.co.uk] kirjoitti:

> I think something needs clearing up here -the good fast clip of Arttu's is actually 10 m/s.Which is about 20 knots.The wind is 10 knots.I would say that could be about what it looks like on film.Is that right? Doug
>
> --- On Tue, 23/8/11, arttuheinonen@heinoset.net <arttuheinonen@heinoset.net> wrote:
>
> From: arttuheinonen@heinoset.net <arttuheinonen@heinoset.net>
> Subject: Re: [harryproa] Re: new videos on youtube
> To: harryproa@yahoogroups.com.au
> Received: Tuesday, 23 August, 2011, 3:12 PM
>
>
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>  
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> Speer sections are for boards. I made the edges slightly sharper than
>
> planned. They are quiet and smooth and there is no vibrations
>
> noticeable. They are 55mm thick 550mm wide. 1.8m in the water. I think
>
> drag is also low. I do not see speed loss on the GPS.
>
>
>
> Regards,
>
>
>
> Arttu
>
>
>
> > Arttu
>
> > Were the Speer sections intended for a board or rudder? The bi-
>
> > directional sections I have seen of his have a relatively large
>
> > radius on the edges. If so then this will lead to heavy vortex
>
> > shedding at higher speed - lots of vibration. Have you observed this?
>
> >
>
> > The centre board can have very small radius edges because it is not
>
> > working over a range of angle like rudders are intended.
>
> >
>
> > The problems I have observed with the under hull uni-directional
>
> > rudders is the extra draft and the inability to see the rudder
>
> > position - need to have angle indicator for slow speed operation.
>
> > Ventilation will not be a problem in most circumstances.
>
> >
>
> > If you reduce the thickness of the rudders they will stall at lower
>
> > angles. The NACA0012 are already quite narrow range.
>
> >
>
> > Rick
>
> > On 23/08/2011, at 4:33 PM, arttuheinonen@heinoset.net wrote:
>
> >
>
> > > Hi,
>
> > >
>
> > > I have considered pivoting centerboard earlier. I still think it might
>
> > > be good solution and a lot safer..
>
> > > The rudders are 12% NACA and they are below the bottom of the boat. I
>
> > > have plans to change their profile to athinner one and longer tapered
>
> > > shape.
>
> > > The daggerboards at the moment are cambered Speer proa sections.
>
> > >
>
> > > Regards,
>
> > >
>
> > > Arttu
>
> > >
>
> > > > Arttu
>
> > > > Gardner proposed a pivoting centreboard off the side of the lw hull.
>
> > > > This was further developed to a board with a clevis off the side of
>
> > > > the hull or off the bottom of the bridge deck (if strong enough)
>
> > > with
>
> > > > a lateral brace across to the cockpit on the ww hull. (It would be
>
> > > > nice to have the board under a beam but you do not want 2 boards).
>
> > > >
>
> > > > The brace will take large compressive force so needs to be large
>
> > > > enough in section to avoid buckling. Also streamlined so it does not
>
> > > > act as a brake when going through waves.
>
> > > >
>
> > > > The board can have a slight camber so it does not require leeway to
>
> > > > produce lift. It can also be made bi-dirctional with small radius
>
> > > > edges as it will only have a narrow range of working angle if sized
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> > > > properly (nominally zero or even negative). This will reduce
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> > > > intensity of vortex shedding with little risk of ventilating.
>
> > > >
>
> > > > The board can be pivoted up when running to reduce drag or for
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> > > > operation in shallow water.
>
> > > >
>
> > > > Need to give a bit of thought to the geometry of the brace and its
>
> > > > mounting pivot so it allows the board to rotate while the brace
>
> > > stays
>
> > > > aligned to flow (a universal or gimbal joint with rotation in two
>
> > > > planes but still torque transmitting - outboard end a ball joint.
>
> > > > The brace also needs to be bi-directional and non-ventilating.
>
> > > >
>
> > > > One observation I have made with brief experience with a proa is the
>
> > > > impact of any hull fouling. The Harryproa hulls are low drag by
>
> > > > virtue of low wave making. The viscous drag is contributing maybe
>
> > > > 90% or more of the total drag - wave drag is thus close to
>
> > > > negligible. This means the hull drag is much more sensitive to
>
> > > > fouling than on most other sailing boats. So I have formed the
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> > > > opinion that keeping the hulls free of fouling will be rewarding in
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> > > > terms of achieving speed potential.
>
> > > >
>
> > > > I am not sure where it was mentioned but someone made the comment
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> > > > that they had operating rudder angles of 10 degrees. If they are
>
> > > > NACA0012 sections then they will ventilate at this angle at higher
>
> > > > speed or have a deep wave trough on the lifting side at slower speed
>
> > > > - neither case is good for performance.
>
> > > >
>
> > > > Rick
>
> > > >
>
> > > > On 23/08/2011, at 3:35 PM, arttuheinonen@heinoset.net wrote:
>
> > > >
>
> > > > > I would like to have only one daggerboard in the middle, but the
>
> > > > > mast is there. I really like increased upwind performance
>
> > > > > daggerboards give. I can not see any other way to do this so
>
> > > far. I
>
> > > > > am interested to hear any ideas. In my opinion rockerless hull
>
> > > > > shape requires some board close to the middle to make it go
>
> > > straight.
>
> > > > >
>
> > > > > Regards,
>
> > > > >
>
> > > > > Arttu
>
> > > > >
>
> > > > > tsstproa [bitme1234@yahoo.com] kirjoitti:
>
> > > > > > So four boards total to control the boat? Spiral up not down! Or
>
> > > > > is this just an experiment to get variable control from different
>
> > > > > concepts? I see multiple combination in controlling helm balance
>
> > > > > with the two fixed and two steerable boards.
>
> > > > > >
>
> > > > > > Thanks for shooting and posting the vid.
>
> > > > > >
>
> > > > > > Todd
>
> > > > > >
>
> > > > > > --- In harryproa@yahoogroups.com.au, arttuheinonen@... wrote:
>
> > > > > > >
>
> > > > > > > Shunting is pretty easy. The harder the wind the better it
>
> > > shunts,
>
> > > > > > > strange?? This is very clear also without the jib. With the
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> > > > > main only
>
> > > > > > > the boat tends to steer upwind with less effort than to lee
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> > > > > side, IF I
>
> > > > > > > use the rear rudder. With the front rudder this is barely
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> > > > > noticeable.
>
> > > > > > >
>
> > > > > > > BUT the rear rudder must be angled to make the boat neutral
>
> > > (10-15
>
> > > > > > > degrees). It will maintain the chosen position bcause of
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> > > friction.
>
> > > > > > >
>
> > > > > > >
>
> > > > > > > Regards,
>
> > > > > > >
>
> > > > > > > Arttu
>
> > > > > > >
>
> > > > > > >
>
> > > > > > >
>
> > > > > > >
>
> > > > > > > > Brilliant videos! Many thanks. Please keep them coming.
>
> > > Speed
>
> > > > > looks to be
>
> > > > > > > > 10 knots on the chart plotter? Wind about the same
>
> > > judging by
>
> > > > > the lack of
>
> > > > > > > > white caps? How easy was it to steer and shunt with only the
>
> > > > > main?
>
> > > > > > > >
>
> > > > > > > > rob
>
> > > > > > > >
>
> > > > > > > > On Mon, Aug 22, 2011 at 2:46 AM, Arttu Heinonen
>
> > > > > > > > <arttuheinonen@...>wrote:
>
> > > > > > > >
>
> > > > > > > > > **
>
> > > > > > > > >
>
> > > > > > > > >
>
> > > > > > > > > Hi ,
>
> > > > > > > > >
>
> > > > > > > > > I uploaded two new videos on youtube. On the first one you
>
> > > > > can see how our
>
> > > > > > > > > mast
>
> > > > > > > > > is bending. There is significant intentional twist on the
>
> > > > > main because of
>
> > > > > > > > > strong
>
> > > > > > > > > wind. We had to furl the jib soon after this. The speed
>
> > > was
>
> > > > > then 7.5 knots
>
> > > > > > > > > upwind with the main only.
>
> > > > > > > > >
>
> > > > > > > > > http://www.youtube.com/watch?v=MOX1YkTrv5c&feature=related
>
> > > > > > > > >
>
> > > > > > > > > On the other video you may see some overall appeareance of
>
> > > > > our boat. There
>
> > > > > > > > > is
>
> > > > > > > > > lots of main sheet . We changed the main sheet to 1:2 and
>
> > > > > installed extra
>
> > > > > > > > > tying
>
> > > > > > > > > points both for the sheet to attach and for tying up
>
> > > > > purposes. I think it
>
> > > > > > > > > wprks
>
> > > > > > > > > now better. It is easier to handle winches now with the
>
> > > > > main sail only,
>
> > > > > > > > > forces
>
> > > > > > > > > are lower.
>
> > > > > > > > > http://www.youtube.com/watch?v=C0SagTSVrL8
>
> > > > > > > > >
>
> > > > > > > > > regards,
>
> > > > > > > > >
>
> > > > > > > > > Arttu
>
> > > > > > > > >
>
> > > > > > > > >
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> > > > > > > > >
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> > > > > > >
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> > > > > >
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> > > > > >
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> > > > > >
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> > > > >
>
> > > > >
>
> > > >
>
> > > > Rick Willoughby
>
> > > > rickwill@bigpond.net.au
>
> > > > 03 9796 2415
>
> > > > 0419 104 821
>
> > > >
>
> > > >
>
> > >
>
> > >
>
> >
>
> > Rick Willoughby
>
> > rickwill@bigpond.net.au
>
> > 03 9796 2415
>
> > 0419 104 821
>
> >
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> >
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