Hi Doug,
Here's a new video of CatPrao ProaCat with centered mast position use double skin wing in 8-14mph winds.
http://www.youtube.com/watch?v=UZzKNmydU-s
I'm not certain to any degree just tinkering. Thinking leeward hull canted with sheer out and keel in. I'm thinking it could be aiding in some sort of dynamic lift when pressed while sailing with the right kind of hull shape. Also aid in heeling moment due to both hulls geometry during heel from canted leeward hull configuration. Windward hull might be better set at a different orientation yet to be discovered? On catprao proacat their cant neutralizes each other and their extreme narrowness negates their drag due to the cant in theory. So not sure of the outcome on wider hulls of dissimilar lengths or any other configuration as of yet.
I got my last iteration of monohull perfectly tuned to sail in a variety of conditions with out adding weight or changing sail size. Mostly due to the leeward side angle, keel rocker and bottom tappered shape from keel to windward side bottom panel.
http://www.youtube.com/watch?v=spK28yj5cEo&feature=related
--- In harryproa@yahoogroups.com.au, Doug Haines <doha720@...> wrote:
>
> That is a good pint - shouldn't you cant the lee hull so it is level only after a bit of a moment starts to pull the sails over?
> I canted my cockpit deck, so it would keep me snugged in better - it felt like you would roll out sometimes when just built level.
> I suppose then should the ww hull be canted too.
> Or is it so minor a change?
> 2 degrees is a millimetre or two at the beam to hulls ?
>
> Doug
>
> --- On Thu, 26/8/10, tsstproa <bitme1234@...> wrote:
>
> From: tsstproa <bitme1234@...>
> Subject: [harryproa] Re: Wings Sails
> To: harryproa@yahoogroups.com.au
> Date: Thursday, 26 August, 2010, 11:52
>
>
>
>
>
>
>
> Â
>
>
>
>
>
>
>
>
>
> No I'm talking about precanted like on catproa. But the 60'ter is the empty leehull. How much drag is gained or reduce precanted at 20 degrees of heel? Mast would be placed on exterior beam outside of hull. Like on catprao.
>
>
>
> Todd
>
>
>
> --- In harryproa@yahoogroups.com.au, Dennis Cox <dec720@> wrote:
>
> >
>
> > Todd,
>
> >
>
> > Boy! we've got to talk! I thought I was a speed freek... Are we talking about
>
> > the same boat? The 60 footer is meant to be a cruiser. At 2 degrees the
>
> > windward hull has left the water. I will be tempted to do that. BUT 20
>
> > DEGREES... in a ten thousand pound boat... with the crystal and china flying out
>
> > of the cabinetry, toilets overflowing, Admiral cussing... I'd have to clean
>
> > more than the floors. (See attached)
>
> >
>
> > Dennis
>
> >
>
> >
>
> >
>
> >
>
> > ________________________________
>
> > From: tsstproa <bitme1234@>
>
> > To: harryproa@yahoogroups.com.au
>
> > Sent: Wed, August 25, 2010 1:19:27 PM
>
> > Subject: [harryproa] Re: Wings Sails
>
> >
>
> > ÂÂ
>
> > Whats the drag when canted 20 degrees?
>
> >
>
> > On the 60' at 2' wide I see an almost symetrical under water plane with a very
>
> > fare shape at 20 degrees of heel. With about 156sqft of wetted surface area at a
>
> > 12''draft.
>
> >
>
> > Todd
>
> >
>
> > --- In harryproa@yahoogroups.com.au, Dennis Cox <dec720@> wrote:
>
> > >
>
> > > Todd,
>
> > >
>
> > > Still fascinated with the flat hull preheeling or canted hulls. In the right
>
> > > condition I swear I can see the leehull on CatPrao generating lift.
>
> > >
>
> > >
>
> > > I sure hope so... seeing that 10% more drag than a rounded hull says it'll be a
>
> > >
>
> > > relative dog in light wind. At least compared to the big cats I'll run
>
> > > against. If it gets any planing... its a whole new ball game!ÂÂÂ
>
> > >
>
> > >
>
> > > Dennis
>
> > >
>
> > > ÂÂÂ
>
> > >
>
> > >
>
> > >
>
> > > ________________________________
>
> > > From: tsstproa <bitme1234@>
>
> > > To: harryproa@yahoogroups.com.au
>
> > > Sent: Wed, August 25, 2010 1:55:24 AM
>
> > > Subject: [harryproa] Re: Wings Sails
>
> > >
>
> > > ÂÂÂ
>
> > > Don't know, Largest boats built 16'ter's built from models. Did exactly what
>
> > >the
>
> > >
>
> > > model did. Scaling is another intricate number game. I use 1/12 scale I would
>
> > > first find where you want the 4.5 tons to sit and design accordingly with what
>
> >
>
> > > beam and with what kind of rocker and how much free board. The model would then
>
> > >
>
> > > be weighted to sit on the scale waterline/draft. Then sailed with no extra
>
> > > weight added. I know you can't scale everything but keeping it in perspective
>
> > > should get you close. Keeping an eye on your models weight, water line, and
>
> > >sail
>
> > >
>
> > > size helps too. If the models weight is too heavey and sitting above waterline
>
> >
>
> > > mark its no good needing more weight more sail area everything gets thrown out
>
> >
>
> > > of perspective. I use balsa wood and CA glue and kyrlon spray paint to seal the
>
> > >
>
> > > wood. The thickest balsa I use is 3/32 on the larger models 1/16 -1/8 on the
>
> > > smaller models. Models are extremely light fragile and don't stand up to alot
>
> > >of
>
> > >
>
> > > out of water abuse.
>
> > >
>
> > >
>
> > > I was going to do a 48'/inch hull. But I'll do a 60'' and attach one of my 36''
>
> > >
>
> > > hulls to it. I'm thinking 12-14''draft on a 18'' beam with a 48'' sheer height.
>
> > >
>
> > > That gets me around 2 ton. Could change as I see it come together.
>
> > >
>
> > >
>
> > > Still fascinated with the flat hull preheeling or canted hulls. In the right
>
> > > condition I swear I can see the leehull on CatPrao generating lift.
>
> > >
>
> > >
>
> > > Todd
>
> > >
>
> > > --- In harryproa@yahoogroups.com.au, Dennis Cox <dec720@> wrote:
>
> > > >
>
> > > > Todd,
>
> > > >
>
> > > > From your experience, have you had any issues scaling to your full size test
>
> >
>
> > > > rig?ÃÆ'‚ How about to far larger... 60', 4.5 tons?
>
> > > >
>
> > > > Dennis
>
> > > >
>
> > > >
>
> > > >
>
> > > >
>
> > > > ________________________________
>
> > > > From: tsstproa <bitme1234@>
>
> > > > To: harryproa@yahoogroups.com.au
>
> > > > Sent: Tue, August 24, 2010 12:46:30 AM
>
> > > > Subject: [harryproa] Re: Wings Sails
>
> > > >
>
> > > > ÃÆ'‚ÂÂÂ
>
> > > > I'll go with my instinct and testing. Somethings amiss here. Look at some of
>
> >
>
> > > >the
>
> > > >
>
> > > > top high end hand launch gliders. Their wings are thin and cambered in a way
>
> >
>
> > > > very similar to my single skin except for their dedicated leading and
>
> > >trailing
>
> > >
>
> > >
>
> > > > edges. Granted theses are thermal gliders hand launched like a boom-rang not
>
> >
>
> > > > winch assisted heavy fast flying thermal soarers. Theramal soarers can
>
> > >achieve
>
> > >
>
> > >
>
> > > > speeds over 60mph where as hand launch thermal gliders very rarely see 30mph.
>
> > >
>
> > > > The l/d ratio's have to fit the speed in which the craft is meant for and the
>
> > >
>
> > > > purpose of the craft and I'd assume the weight of the craft as well.
>
> > > >
>
> > > >
>
> > > > Not a number guy , I go by past experiences, on instinct, and by what I see
>
> > > > working.
>
> > > >
>
> > > >
>
> > > > I could get the double skin to work better but to me the outcome wouldn't be
>
> >
>
> > > > worth it. Its sail seems sluggish none respnsive or slow to respond . Driving
>
> > >a
>
> > >
>
> > > >
>
> > > > car with a lose steering wheel. The single skin bamb... 911 porche. super
>
> > > > responsive goes where you point it when you point it and tells you when you
>
> > > >have
>
> > > >
>
> > > > gone to far quickly all ways in touch.
>
> > > >
>
> > > > I have done other double skin wings and its starting to bring back memories
>
> > >of
>
> > >
>
> > >
>
> > > > why I didn't proceed.
>
> > > > http://www.youtube.com/watch?v=YDzG98DPvto
>
> > > > http://www.youtube.com/watch?v=YDzG98DPvto
>
> > > > http://www.youtube.com/watch?v=_PaWgwc4HwI&feature=related
>
> > > >
>
> > > > But I always keep coming back to this.
>
> > > >
>
> > > > http://www.youtube.com/watch?v=CCSoZOwQY6g
>
> > > >
>
> > > > Cause is it just works so damn well.
>
> > > >
>
> > > > Todd
>
> > > >
>
> > > >
>
> > > > --- In harryproa@yahoogroups.com.au, Rick Willoughby <rickwill@> wrote:
>
> > > > >
>
> > > > > Todd
>
> > > > > The thin section will perform slightly better than a fat section.
>
> > > > > The fat section is more forgiving. You need less sail area and the
>
> > > > > maximum lift will be more than the maximum drag.
>
> > > > >
>
> > > > > The fat section shape should be close to flat one side with nice
>
> > > > > rounding on the nose - something like attached mirrored.
>
> > > > >
>
> > > > > It should be a bit more than half the area you have now.
>
> > > > >
>
> > > > > The higher lift of the fat section is negated somewhat by the higher
>
> > > > > induced drag. You can reduce this negative to some degree by fencing
>
> > > > > the bottom. In fact any of the fixed wings should be improved by
>
> > > > > fencing the bottom either by having them operate close to a deck or
>
> > > > > fit a plate on the bottom of the sail. You could then carry the full
>
> > > > > chord all the way to the bottom.
>
> > > > >
>
> > > > > I could not get to the photo on the link you posted.
>
> > > > >
>
> > > > > Rick
>
> > > > > ÃÆ'Æ'¯ÃÆ'‚¿ÃÆ'‚¼
>
> > > > > On 23/08/2010, at 3:58 AM, tsstproa wrote:
>
> > > > >
>
> > > > > > No, you can not just let go and expect it to depower you have to
>
> > > > > > put the sail to the correct position to depower via controls. I
>
> > > > > > think of it as more of a mental block or learning curve in sailing
>
> > > > > > with this type of sail.
>
> > > > > >
>
> > > > > > The sail I have now is 2% thickness with a 9.6% camber. Or 1/4''
>
> > > > > > thick x 13 wide x 1.25 deep at center chord. The camber is pretty
>
> > > > > > consistent staying at about 9.6 though the bottom 3/4 of sail
>
> > > > > > coinciding with its chord the top 1/4 or so becomes alittle less.
>
> > > > > >
>
> > > > > > To me If I went with a 2.6'' wing thickness it kinda defeats the
>
> > > > > > whole purpose of going fast. Sure people will argue higher lift to
>
> > > > > > drag coefficient reduces drag is more efficient has a greater range
>
> > > > > > but look at that section of air it has to cut out. Vs 2% thickness
>
> > > > > > that has a camber of 10% its not a flat plate. Would it really sail
>
> > > > > > faster have better control have better range?
>
> > > > > >
>
> > > > > > Maybe your confusing wing thickness with camber?
>
> > > > > >
>
> > > > > > Here's a clip of a few more thorugh the water hull shots loading
>
> > > > > > the leeward hull while sailing into the wind to see what happens.
>
> > > > > >
>
> > > > > > http://www.youtube.com/watch?v=LrezrEfQj68
>
> > > > > >
>
> > > > > > Did a 180 sq inch 23''span ,10 '' chord, 2'' thick. Just to test
>
> > > > > > double skin vs
>
> > > > > > single skin Asymmetrical section.
>
> > > > > > Pics here
>
> > > > > > http://groups.yahoo.com/group/Wind_Powered_Shunting_Craft/photos/
>
> > > > > > album/2009757739/pic/list
>
> > > > > >
>
> > > > > > Here's first test 180 sq'' bi-directional asymmetric sail.
>
> > > > > > http://www.youtube.com/watch?v=uRYTVcfmns8
>
> > > > > >
>
> > > > > > The double skin asymmetric sail creates very little drive vs the
>
> > > > > > single skin cambered. Its heavier has less range and to me seems
>
> > > > > > piss poor in performance. Unless in higher winds . I can see where
>
> > > > > > a double skin could be improved upon to make work ,being a
>
> > > > > > combination of single skin camber and double skin thickness. But
>
> > > > > > were is the innovation in that all you have to do is look at the
>
> > > > > > oracle wing sail sail. I'll stick with my true asymmetrical single
>
> > > > > > skin Bi- directional for now.
>
> > > > > >
>
> > > > > > Todd
>
> > > > > >
>
> > > > > > --- In harryproa@yahoogroups.com.au, Rick Willoughby <rickwill@>
>
> > > > > > wrote:
>
> > > > > > >
>
> > > > > > > Todd
>
> > > > > > > By feathering I am referring to a full size version where you
>
> > > > > > want to
>
> > > > > > > release sail force by releasing the sheet or whatever is controlling
>
> > > > > > > the sail AoA. The symmetrical sail does not feather when released or
>
> > > > > > > only over a very narrow range. An interesting test would be to
>
> > > > > > > release your control rods to the mast and see where the sail
>
> > > > > > rotates.
>
> > > > > > >
>
> > > > > > > The middle mounted rudders do provide a load release mechanism that
>
> > > > > > > allows leeway when clear of the water. I can see the benefit in
>
> > > > > > that.
>
> > > > > > >
>
> > > > > > > At speeds above a few knots on a full size craft ventilation will be
>
> > > > > > > performance limiting. Hence I see merit in under the hull rudders.
>
> > > > > > > They could be under the windward hull if you want some force release
>
> > > > > > > mechanism. The instant that they ventilate will cause the boat to
>
> > > > > > > round up a little so some inbuilt protection. If the front one goes
>
> > > > > > > first then there will be an instant of lee helm before the aft one
>
> > > > > > > lets go.
>
> > > > > > >
>
> > > > > > > Your cambered thin wing will have a working range of a few degrees
>
> > > > > > > when on the wind. The lift drops to under half about 5 degrees
>
> > > > > > > either side of maximum lift. The 10% series 07 foil will work over
>
> > > > > > > twice that range and if you went up to a 20% thick section it would
>
> > > > > > > have twice the lift and work over 25 degree range - so more
>
> > > > > > > progressive. Having double the lift coefficient allows you to halve
>
> > > > > > > the sail area. This means the maximum drag when the sail is
>
> > > > > > > perpendicular to the wind is halved so risk of capsize is reduced.
>
> > > > > > > You can provide this same protection by putting more curve into your
>
> > > > > > > thin sail and reducing the area but it will still only have a narrow
>
> > > > > > > range of operation.
>
> > > > > > >
>
> > > > > > > Rick
>
> > > > > > > On 19/08/2010, at 2:58 PM, tsstproa wrote:
>
> > > > > > >
>
> > > > > > > > Thanks Rick
>
> > > > > > > >
>
> > > > > > > > What do you mean by feathering?
>
> > > > > > > >
>
> > > > > > > > More range in what way pointing ability or same sail size for
>
> > > > > > > > higher wind strengths or both ?
>
> > > > > > > >
>
> > > > > > > > I'm sailing right in front of a shallow shelf so tring to keep
>
> > > > > > boat
>
> > > > > > > > close for through water hull shots. At 5:00 in Last part of video
>
> > > > > > > > thinking of a way to show leeway if any. I'm not moving the
>
> > > > > > > > steering boards just manipulating the sail only. Boat pretty much
>
> > > > > > > > stays in same position as it see-saws back and forth actually
>
> > > > > > gains
>
> > > > > > > > ground in the puffs.
>
> > > > > > > >
>
> > > > > > > > Also starting at 2:35 on the clip look as it heels and slides
>
> > > > > > > > sideways don't no if thats a good thing or not, but better than
>
> > > > > > > > digging and catching an edge. An argument for center hung
>
> > > > > > boards vs
>
> > > > > > > > leeward hung boards might correct of hinder the situation. I know
>
> > > > > > > > the canted of hull helped the slide.
>
> > > > > > > >
>
> > > > > > > > No, I'm using symmetrical.
>
> > > > > > > >
>
> > > > > > > > When I put the camera down the performance goes up two hands vs
>
> > > > > > > > one. Towards the end of the day I was tring everything to get
>
> > > > > > it to
>
> > > > > > > > ride on leeward hull alone in the 4.5 mph wind it wouldn't thats a
>
> > > > > > > > good thing to me. I'm hoping in about 6 to 8 range it will still
>
> > > > > > > > stay somewhat planted. In more wind canting the rig to windward or
>
> > > > > > > > reducing sail size.
>
> > > > > > > >
>
> > > > > > > > Todd
>
> > > > > > > >
>
> > > > > > > > --- In harryproa@yahoogroups.com.au, Rick Willoughby <rickwill@>
>
> > > > > > > > wrote:
>
> > > > > > > > >
>
> > > > > > > > > Todd
>
> > > > > > > > > Very nice work.
>
> > > > > > > > >
>
> > > > > > > > > It is so simple with the rigid bi-directional wing. The only
>
> > > > > > problem
>
> > > > > > > > > is lack of feathering but that could be overcome.
>
> > > > > > > > >
>
> > > > > > > > > A thick sail section like I did for the rudder would have wider
>
> > > > > > > > range
>
> > > > > > > > > of control. It might be a bit more progressive on the controls
>
> > > > > > > > >
>
> > > > > > > > > Are you using asymmetrical rudders?
>
> > > > > > > > >
>
> > > > > > > > > Rick
>
> > > > > > > > > On 19/08/2010, at 11:05 AM, tsstproa wrote:
>
> > > > > > > > >
>
> > > > > > > > > > CatPrao ProaCat AURORA 36'' x 1/2'' x 3'' with 12'' rocker.
>
> > > > > > hulls
>
> > > > > > > > > > are canted 20degrees outward.
>
> > > > > > > > > >
>
> > > > > > > > > > http://www.youtube.com/watch?v=FCEvPdnhShk
>
> > > > > > > > > >
>
> > > > > > > > > > Todd
>
> > > > > > > > > >
>
> > > > > > > > > >
>
> > > > > > > > >
>
> > > > > > > > > Rick Willoughby
>
> > > > > > > > > rickwill@
>
> > > > > > > > > 03 9796 2415
>
> > > > > > > > > 0419 104 821
>
> > > > > > > > >
>
> > > > > > > >
>
> > > > > > > >
>
> > > > > > >
>
> > > > > > > Rick Willoughby
>
> > > > > > > rickwill@
>
> > > > > > > 03 9796 2415
>
> > > > > > > 0419 104 821
>
> > > > > > >
>
> > > > > >
>
> > > > > >
>
> > > > >
>
> > > > > Rick Willoughby
>
> > > > > rickwill@
>
> > > > > 03 9796 2415
>
> > > > > 0419 104 821
>
> > > > >
>
> > > >
>
> > >
>
> >
>