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      Abbreviated rules   07/28/2017

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Tornado-Cat

The winning foils

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Simon(or anyone else for that matter) do you have a link to foiling video of any other foiling cat doing so with a nose down attitude?

 

PS-I've just gone thru recent A Class, Flying Phantom and GC32(at Riva Cup) and no nose down attitude similar to the AC boats. Maybe there is one out there but I haven't found it.......

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Sorry, Doug, but we don't video our sessions and it seems that neither do other top guys. I think of the people who will be in with a chance at the upcoming worlds, all I have seen is one short clip. Hopefully you will see some video from the A Class worlds, but I suspect you will need to pay attention because from what I have seen, there might not be very many who have taken it to that stage yet. I think we are likely to see 2 or 3 guys who are way ahead of everybody else.

 

I also think that bow down attitude is something that on the A's is rather condition dependent. I would not be going too far down that route in waves offwind, because you want the bow up so it doesn't hit the wave in front.

 

The other thing we are very aware of is that what works well in training might not work so well on the race course. For instance, we think we will see a fair amount of upwind foiling, given the right conditions, but that might change in a big fleet where it might pay to sail more conservatively. Ultimately, it's not actually about maximum boats speed but maximum VMG round the whole course ompared with other boats. For instance, it might be that we only see upwind foiling when it is possible to put the bow down in a lift to get over the fleet. If you are not foiling upwind for the majority of the time, setting the boat up for bow down attitude is probably not a good idea and adjusting pitch on the fly is too complex. So what can be shown in training to work might not be what will win a worlds. As we all get better and the boundaries are pushed further and further, i believe we will see that once boats are foiling for most of the time, we will have bow down attitudes in flatter water.

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Have you seen the differenceS ?

 

 

Good catch, TC! I see the reverse curve on the vertical portion of the Oracle foil in the small pix. I'll have to give some thought to what that might do.....

 

Also a good illustration of the nose up angle of the rudder foil which allows the nose down attitude of the boat when foiling--but why is the nose down attitude of the boat faster?

 

Right.

I think we can also see other differences. The left foils seems different from the right one. The lifting part seems wider and with a scoop (not sure though, it could be the photo) . Could it be a light wind foil ?

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Have you seen the differenceS ?

 

 

Good catch, TC! I see the reverse curve on the vertical portion of the Oracle foil in the small pix. I'll have to give some thought to what that might do.....

 

Also a good illustration of the nose up angle of the rudder foil which allows the nose down attitude of the boat when foiling--but why is the nose down attitude of the boat faster?

 

Doug

I suspect that the reverse curve is simply trying to get the board further outboard.

 

 

 

That was also my first guess. However I am wondering wether it could be a way to set the cant with less power. Hard to know

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Have you seen the differenceS ?

 

 

Good catch, TC! I see the reverse curve on the vertical portion of the Oracle foil in the small pix. I'll have to give some thought to what that might do.....

 

Also a good illustration of the nose up angle of the rudder foil which allows the nose down attitude of the boat when foiling--but why is the nose down attitude of the boat faster?

 

SR explained a few months ago that they going downwind nose down so that the bow could be horizontal upwind.

Another possibility could be to increase the pressure on the stern while speed is increasing, in order to make sure to keep the rudder in the water ?

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Simon do you know why they have a bow down attitude!.. by your statement above you obviously do not!....

Interesting?....

Simon... come in Simon you've gone all silent Simon.

 

Been caught out Simon! Or is that Hasn't or your other sock puppets?...

 

 

And don't come back with the "I'm ignoring you" line!....

 

I, like others, know you are full of it!

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Perhaps bow down means that the rudders are lifting more than the main foils. When the main foils start to rise - bringing the bow up - the rudder's increased angle of attack more than compensates which carries the stern up, and the bow back down.

 

It was said that a big piece of the puzzle Is control. Bow down may be a method for self correcting fore/aft ride height control. And more control equals more speed.

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Simon do you know why they have a bow down attitude!.. by your statement above you obviously do not!....

Interesting?....

Simon... come in Simon you've gone all silent Simon.

Been caught out Simon! Or is that Hasn't or your other sock puppets?...

And don't come back with the "I'm ignoring you" line!....

I, like others, know you are full of it!

It seems Carbonator has a new identity... Same crap, different name!

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Remember that as well as all the possible better airflow over the tramp and improved endplate effects, by being bow down will also improve rig efficiency and make those jibs much better at doing their thing.

 

If it weren't for the fact that forestays are there to hold up the rig - leading elements would (under MOST circumstances - be better off being perpendicular to the flow of air - i.e. vertical)

 

Not much of a gain but everything helps.

 

Personally, also being bow down gives momentary longer time to control the unwanted wheel/tail stand and conversely, a loss of lift episode, would result in the hulls spearing in slightly to the water or wave, rather than bellyflopping; thereby preserving a little more momentum.

 

The best reason however above all of these is that it gives the Helm a better view forward - rather than just looing at a bunch of heads backs & shoulders - which brings me to my pet peeve - why with all the debate about a deficit of power to run the hydraulic systems do we not see recumbent bike pedalling stations for the crew down out of the air flow?? Even the helms could be on a bike style set up pedalling whilst they steer......

 

Anyway - all of these "possible" reasons lead towards a bow down stance - one is unlikely to be campaign winning move - but combined they all add up to progress and refinement.

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Simon do you know why they have a bow down attitude!.. by your statement above you obviously do not!....

Interesting?....

Simon... come in Simon you've gone all silent Simon.

 

Been caught out Simon! Or is that Hasn't or your other sock puppets?...

 

 

And don't come back with the "I'm ignoring you" line!....

 

I, like others, know you are full of it!

 

So as well as being a troll, you can't read? Go back up the thread and you will see I answered you directly. Post 100 to be precise. Rather funny that a person who hides behind stupid online personas and who changes them trying to be so smart thinks that one of the few people who uses his real identity has sock puppets. Why on earth would I bother. Never have, never will.

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Normally on most foilers that I'm familiar with if the rudder leading edge is vertical then the rudder foil is set at 90 degrees to that. That is generally zero degrees AOI with reference to the static waterline(whereas the main foil is +2.5 degrees).

However, that's not the case with Oracle's 45 where the rudder foil is clearly nose up to allow the whole boat to foil nose down. On the 45's the rudder AOI is not adjustable on the water but on the 50's it will be :+ or minus 1.5 degrees. It's interesting to contemplate what "zero" will be on a 50.....

 

2wltro0.jpg

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Seems to me the foil angle of attack would be the same regardless of the foiling attitude. As would angle of incidence(red below) relative to the flight waterline:

Note: on many foilers the static and flight waterlines are parallel(after takeoff)-not on the nosedown AC45 so the flight waterline is the better reference.

 

2qusz03.jpg

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Am I the only one here to see that that the left foil does not only have an S but also a wider angle for the lifting surface and a banana shape ?

The "uptip" and the L would be replaced by a more vertical foil but a more "rounded" lifting surface ?

 

 

post-43482-0-87864700-1464470828.jpg

post-43482-0-94557700-1464471403_thumb.jpg

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Simon....Here is where I have a problem with your so called testing.

 

You say you do theoretical testing. I presume you mean development?.... please explain what you develop, what is the basis, and where do your source your ideas.

 

Then there's your practical testing. This is not obviously in a controlled hydro and or aero environment but on a boat in the ocean/ lake and with many uncontrolled variables.

 

Are you testing by yourself, what test equipment do you use and how to you verify and validate your findings.

 

Who checks your figures.

 

having worked in both aero, but mainly Hydro, testing labs for a number of years I would be interested in how you develop and test as well as how you use your data to create accurate results.

 

If you are just measuring speed and VMG with GPS and not comparing the many influences upon these measurements within your test times and between you test time data then you are wasting your time. I would like to know you test method and its accuracy.

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Seems to me the foil angle of attack would be the same regardless of the foiling attitude. As would angle of incidence(red below) relative to the flight waterline:

Note: on many foilers the static and flight waterlines are parallel(after takeoff)-not on the nosedown AC45 so the flight waterline is the better reference.

 

2qusz03.jpg

wtf have you been smoking???

 

You better rethink you theory!

 

 

 

Do you think the bow down comes from foil ( front and back) set, platform design, up or maybe weight distribution, rig / sail loading, or a combo.

 

I would be interested in your thoughts

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Am I the only one here to see that that the left foil does not only have an S but also a wider angle for the lifting surface and a banana shape ?

The "uptip" and the L would be replaced by a more vertical foil but a more "rounded" lifting surface ?

 

 

 

I'm not so sure. The left tip is very hard to make out. There must be another picture somewhere-I'll see what I can find.

 

3009x8g.jpg

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Seems to me the foil angle of attack would be the same regardless of the foiling attitude. As would angle of incidence(red below) relative to the flight waterline:

Note: on many foilers the static and flight waterlines are parallel(after takeoff)-not on the nosedown AC45 so the flight waterline is the better reference.

 

2qusz03.jpg

+1 Foil AOA is wrt the waterline not whatever attitude they fly the platform at.

 

They vary ride height (they fly higher up off the water downwind than upwind) to vary how much of the vertical portion is submerged, for improved VMG. But attitude-wise the slight nose-down must accomplish several things aerodynamically including less risk of a gust or otherwise-induced induced nose-up; and possibly also improved stick-to-water righting moment? I keep thinking back to the aero comments made by BAR's Andy Claughton in an older video link that I re-posted recently. I've wondered here before also about what affect a nose-down attitude has on the wing's center of effort; it must surely move forward the more nose-down you are? That could affect the load balance between the mains and the rudders, and other considerations like helm balance.

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In the 34th AC I thought that the bow down attitude downwind was due to the inability to adjust the angle of the rudder foil while racing - It was my belief that they had to find a compromise between the lift generated by the slower upwind speed and the greater lift created by the higher downwind speed. Since they couldn't reduce the angle downwind, the stern over-lifted at the greater speed. I would think that, as they got faster upwind, requiring less up angle on the rudders, the downwind bow down attitude would have been reduced....

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Where are you Simon and Doug.

 

It appears that when challenged on the detail of your statements, claims... you go missing in action.

 

Its no good aspinnin the big talk when you have not graduated above " junior league".

 

As i thought.... all image and no substance!

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Related to the nose down setup: don't rudders seem to be getting longer?

 

They do to me.........

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Related to the nose down setup: don't rudders seem to be getting longer?

That's in the design rule, right? Maybe it was intended by the designers to allow for better control wrt ride height. Would be silly to enable sailing downwind riding higher up off the water if it ran the risk of the stabs breaking the surface.

Related to the nose down setup: don't rudders seem to be getting longer?

That's in the design rule, right? Maybe it was intended by the designers to allow for better control wrt ride height. Would be silly to enable sailing downwind riding higher up off the water if it ran the risk of the stabs breaking the surface.

 

edit, silly phone

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Simon....Here is where I have a problem with your so called testing.

 

You say you do theoretical testing. I presume you mean development?.... please explain what you develop, what is the basis, and where do your source your ideas.

 

Then there's your practical testing. This is not obviously in a controlled hydro and or aero environment but on a boat in the ocean/ lake and with many uncontrolled variables.

 

Are you testing by yourself, what test equipment do you use and how to you verify and validate your findings.

 

Who checks your figures.

 

having worked in both aero, but mainly Hydro, testing labs for a number of years I would be interested in how you develop and test as well as how you use your data to create accurate results.

 

If you are just measuring speed and VMG with GPS and not comparing the many influences upon these measurements within your test times and between you test time data then you are wasting your time. I would like to know you test method and its accuracy.

You don't actually know what you are talking about, do you. If you did, you wouldn't be posting this sort of crap, because it shows you have zero idea about how you go about developing faster boats.

 

Yesterday we were on the water doing the final testing before the team departs for the A Class worlds. There were 6 boats, including 2 Olympians, multiple world champions, an America's Cup winner plus an ISAF sailor of the year. I think that between us, we might have a pretty good idea of how to go about developing and testing new ideas, systems and technology but thanks for your concern about whether we are doing it correctly.

 

This is the last time I will feed an anonymous troll. You constantly write contrary views, with little to no substance to back those views up and occasionally making claim to specialist knowledge. Yet as with most keyboard warriors, unanimity is your shield against being proven to be a total fraud, because you could just as easily be a 15 year old fanboy or a senile senior citizen as you could be somebody worth listening to. I don't know if I am worth listening to, but at lest people are able to decide for themselves because it is easy to find out who I am as I use my real name and have never tried to hide my identity. Many on here know my full sailing career, what I have sailed and at what level, which teams have been in, who I have sailed with and who I have coached. In the end, without evidence to the contrary, it is best to assume that somebody who is anonymous and is constantly taking contrary views is nothing more than a troll. So until we see some evidence you are worth interacting with, I will get back to my homework

post-19044-0-61789700-1464561889.jpg

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Related to the nose down setup: don't rudders seem to be getting longer?

That's in the design rule, right? Maybe it was intended by the designers to allow for better control wrt ride height. Would be silly to enable sailing downwind riding higher up off the water if it ran the risk of the stabs breaking the surface.

Humm, seems that the rules give a minimum, not a maximum, unless there is another article I have not seen.

This rudder seems definitively longer that the first ones.

post-43482-0-00257100-1464562987_thumb.png

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Again, this longer rudder is a trend being seen in a number of development classes that allow foiling.

 

I think there are 3 issues. First, as the boat rises and you have less rudder blade in the water, the more sensitive the steering becomes. It gets to the point of being really skittish was in some conditions is close to scary. More rudder in the water equals greater control. Next, as the foil gets close to the surface, you begin to risk ventilation. It doesn't take very much for a little air to be sucked down the front of the rudder blade and which leads to the foil washing out resulting in both loss of steering and lift. Finally, getting the foil below the disturbed water coming off the main foils seems to be highly beneficial.

 

The downside is that the rudder blades have to be a lot stronger as the loads seem to go up exponentially. This begins to get difficult, as the thickness of laminate needed is now influencing the minimum cord that can be used in the section. Although I doubt it has a real impact in the AC boats, in the A's we have the issue that it is leading to heavier and heavier foils. The one thing we have learnt is that rudder blades cannot be too stiff.

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Simon:" Finally, getting the foil below the disturbed water coming off the main foils seems to be highly beneficial."

Isn't the rudder foil on a 45 above the main foil(like a Moth) and many other foilers? It would have to be way below the main foil to avoid the downwash due to lift.

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post-30-0-31751400-1464575612_thumb.jpg

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I don't think the rudders are longer to be deeper in the water, but to put the nose down.

 

The more I am thinking about it, the more it seems that these are very fast boats, they close to 50 kts and always sail front wind, pushing the cat to the back. So what if the bow down is to increase the power of the boat ?

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^ +1

 

I also assumed that deeper rudders could be needed to place the rudder foils below the wake from the main foils, but of course they would have to be very deep to avoid the downwash.

 

And I like Simon's point about the deeper the rudder the stronger they have to be to cater for the increased leverage on them.

 

If the rudders are getting deeper, then does this mean the main foils are even deeper (I've not really studied any photos, hence the question in line with Doug's observation above).

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Doug

 

If you read my post again, I was referring to development classes like the Moth and A Class, and not the AC 45's as such. If any of it applies, great. As for the length of Moth rudders, I am pretty sure that current Moth rudders go deeper than the main foil. I said this to a Moth sailor yesterday (we were discussing depth of A Class rudders) and he didn't contradict me. However, I have also been looking for pictures and I haven't found one that is definitive either way, because I cannot be sure if it is the angle of the photo causing a distortion or if it is actually longer.

 

One of the A Class team yesterday was running a slightly shorter rudder (approx 100mm) and you could really feel the difference because of the lack of depth.

 

On a slight hijack, yesterday was the final training day for our little A Class group before they head off to the worlds. The fastest downwind speed recorded by GPS was a rather "disappointing" 21.9 knots. except that we never recorded more than 9 knots of breeze the whole time. It is possible we saw 10 knots in a gust, but that wasn't measured. IIRC, the fastest speed of this autumn has been 29 knots.

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Isn't the rudder foil on a 45 above the main foil(like a Moth) and many other foilers? It would have to be way below the main foil to avoid the downwash due to lift.

As an aside: do all/most Moths have moveable rudder foil flaps as shown, vs. a raking rudder stock?

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They have one or the other. I don't know for sure but it seems that a lot of Moths are adjusting the whole rudder angle rather than using a rudder flap.

======================

The rudder on a 45, set up for nosedown flight, may actually be longer than the main foil when sitting on its static waterline but I'd bet that the rudder foil runs just above the main foil to avoid its downwash when foiling.

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Simon....Here is where I have a problem with your so called testing.

You say you do theoretical testing. I presume you mean development?.... please explain what you develop, what is the basis, and where do your source your ideas.

Then there's your practical testing. This is not obviously in a controlled hydro and or aero environment but on a boat in the ocean/ lake and with many uncontrolled variables.

Are you testing by yourself, what test equipment do you use and how to you verify and validate your findings.

Who checks your figures.

having worked in both aero, but mainly Hydro, testing labs for a number of years I would be interested in how you develop and test as well as how you use your data to create accurate results.

If you are just measuring speed and VMG with GPS and not comparing the many influences upon these measurements within your test times and between you test time data then you are wasting your time. I would like to know you test method and its accuracy.

 

You don't actually know what you are talking about, do you. If you did, you wouldn't be posting this sort of crap, because it shows you have zero idea about how you go about developing faster boats.

 

Yesterday we were on the water doing the final testing before the team departs for the A Class worlds. There were 6 boats, including 2 Olympians, multiple world champions, an America's Cup winner plus an ISAF sailor of the year. I think that between us, we might have a pretty good idea of how to go about developing and testing new ideas, systems and technology but thanks for your concern about whether we are doing it correctly.

 

This is the last time I will feed an anonymous troll. You constantly write contrary views, with little to no substance to back those views up and occasionally making claim to specialist knowledge. Yet as with most keyboard warriors, unanimity is your shield against being proven to be a total fraud, because you could just as easily be a 15 year old fanboy or a senile senior citizen as you could be somebody worth listening to. I don't know if I am worth listening to, but at lest people are able to decide for themselves because it is easy to find out who I am as I use my real name and have never tried to hide my identity. Many on here know my full sailing career, what I have sailed and at what level, which teams have been in, who I have sailed with and who I have coached. In the end, without evidence to the contrary, it is best to assume that somebody who is anonymous and is constantly taking contrary views is nothing more than a troll. So until we see some evidence you are worth interacting with, I will get back to my homework

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Simon. How did I know you would pull the troll line out!?... oh that's right, people do that when they are exposed as spin doctors/ bullshitters! And a excuse to hide!

 

My pedigree is at a higher level than you will ever achieve both on and off the water.

 

As I thought, you are just a sailor who thinks that sailing his A class with his mate qualifies himself as a hydro/ aero specialist.

 

To think that you think foil design is developed on the water, without comprehensive analysis and design just proves what a complete bullshitter you, and your mates here, are.

 

You guys on this thread just " blow smoke up each other's arse" pretending you are furking gurus. But back it up with utter bullshit and no experience.

 

If you followed my other posts in fix it anarchy, you will see my pedigree! I have spend a lifetime in the industry.

 

For you to state the " nose down attitude" is done because it is faster is just a cop out! You don't actually know do you!

 

Same as doug Lords diagrams!... what a nut case.

 

The nose down has more to do with the horizontal portions of the foils, and how they are angled, chambered and shaped, than any vertical section depth or length of the rudder etc. Also the wing and jib loading COE drive this nose down attitude as well as the deck shape.

 

Simon I don't expect you will answer any of my posts as you will do the typical bullshitters thing and now hide away.

 

Fast boats come from fast design, superior development, infinite testings, lab physical testing, model comparison ( computer and in water/ air), comparative analysis, peer reviews etc... before finalization to build!

 

It does not come from club sailors going out and randomly comparing in differing conditions, with differing sailors and boat setups.

 

The randomness of you statements and testing just proves you to be in the Little league!

 

For you to state want you have just shows what a bullshitter you are.

 

For others to believe you is just laughable.

 

If you were as half as good as you think you are!.... you would be on the team!

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Doug

 

If you read my post again, I was referring to development classes like the Moth and A Class, and not the AC 45's as such. If any of it applies, great. As for the length of Moth rudders, I am pretty sure that current Moth rudders go deeper than the main foil. I said this to a Moth sailor yesterday (we were discussing depth of A Class rudders) and he didn't contradict me. However, I have also been looking for pictures and I haven't found one that is definitive either way, because I cannot be sure if it is the angle of the photo causing a distortion or if it is actually longer.

 

One of the A Class team yesterday was running a slightly shorter rudder (approx 100mm) and you could really feel the difference because of the lack of depth.

 

On a slight hijack, yesterday was the final training day for our little A Class group before they head off to the worlds. The fastest downwind speed recorded by GPS was a rather "disappointing" 21.9 knots. except that we never recorded more than 9 knots of breeze the whole time. It is possible we saw 10 knots in a gust, but that wasn't measured. IIRC, the fastest speed of this autumn has been 29 knots.

As I thought! GPS trialling!... little league simonN!!!... little league!

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Are the lifting portions of the board foils symmetrical or asymmetrical? Rudder lifting surfaces?

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On many foilers the rudder hydrofoil is symmetrical because the rudder foil will lift up and pull down(automatically on many). Main foils on AC 45's are asymmetrical because they just lift vertically. But the main foils on some cats/tris(Whisper, S9, Osprey, Rave, Hobie Trifoiler, Skat) are symmetrical because they also lift up and pull down-the windward foil is designed to be able to develop downforce/negative lift. This is controlled automatically by dual ,independent surface sensors(wands on most- "feelers" on the trifoiler). The surface sensors move the whole foil(trifoiler) or a flap attached to the foil(all the others).

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Are the lifting portions of the board foils symmetrical or asymmetrical? Rudder lifting surfaces?

On most modern cats, including the AC boats, the foils are a mix. On the rudders, it is most common to see symmetrical foils, although we are now seeing slightly asymmetric foils being being tried - I am pretty certain that the slight asymmetry you can see on the OR rudders above is not an optical illusion as I also believe I have spotted this before. The interesting thing is that they are slightly favouring pull down, as they set the windward foil to provide righting moment.

 

As for main foils, most modern cat foilers have a combination of symmetrical and asymmetric sections in the same foil. The upper sections tend to be symmetrical, while the lower sections or uptick parts tend to be asymmetric. The amount of asymmetry is closely tied to the angle between the vertical and horizontal/uptick section - the flatter it is, the more asymmetry you can run. As Doug points out, this changes if the boat is using the windward main foil to provide righting moment, but the majority of the current boats have moved away from that approach, with one notable exception. Those boats use a flap and wand, with the flap turning a symmetrical section into an asymmetric one in response to the wand movement.

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At what boat speed can an A Cat start to foil? Also wind speed?

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Some foiler builders are going for light air foiling based on the idea that a foiler should be able to use the whole wind range : the Whisper guys claim their boat will foil in 4kts of wind. But most amazingly the new Quant 23 foiling keelboat(!) takes off in about 5 kts wind! Sorry I don't know how early an A Cat will take off....

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At what boat speed can an A Cat start to foil? Also wind speed?

As with all foilers, it's different upwind to downhill. technique is all. Off the wind, you can fly with 7 knots of wind, although if you are really good, you will probably get airborne in a bit less. You are probably doing about 10 knots of boatspeed, but again, with technique, that can come down a bit. Upwind, because of the different loading of the foils, you need about 12 knots of breeze to be properly foiling and a bit more than that in boatspeed terms.

 

As said, technique is all. On Sunday, we had 5 foilers on the water with winds of no more than 10 knots and most of the time it was 7-8 knots, which fell away in the last hour on the water. 3 of the boats were regularly foiling downhill, until the breeze crapped out. The best 2 sailors got a little upwind foiling, but it was tough and there were only marginal gains on VMG. The other 2 sailors only got up a few times and for fairly short distances.

 

It is also hard to determine the exact boatspeed for takeoff, because you have to be fairly physical and time certain actions exactly. It's not as simple as with a plane, where you reach a certain speed and the wings are producing enough lift for take off. Because of the sideways loading on the foils, you have to have the technique of sheeting out and then back in at the right moment so as to unload the foils a bit and this helps the boat rise (in foiling, sheeting out causes the boat to rise and sheeting in pushes it down). So some without good technique probably need another 2 or even 3 knots fo boatspeed before their boat will foil.

 

The other factor is that different foils change the take off point very noticeably. A general rule of thumb seems to be that the earlier the take off speed, the slower the ultimate top end speed is. In addition, somke foils become pretty scary as they get up to top speed, so even though they might be both fast and capable of early foiling, they are just too unstable for overall good vmg round the course. There are also other trade offs which complicate the situation more.

 

In short, I think wind speed is far more relevant in predicting foiling than boatspeed. We are just about at the point of foiling downwind in most conditions we are race in, although on really light days, we cannot. Our class rules only allow for 1 set of foils for a regatta, so we always have a bit of a compromise.

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(in foiling, sheeting out causes the boat to rise and sheeting in pushes it down).

OK. Another possible thing that could be going on in "Beast Mode," as seen in a few videos.

 

Or "pumping," as some might say.

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(in foiling, sheeting out causes the boat to rise and sheeting in pushes it down).

OK. Another possible thing that could be going on in "Beast Mode," as seen in a few videos.

 

Or "pumping," as some might say.

 

I remain certain that what we saw was as much to do with foil loading as anything else. Pumping is about propulsion and I also remain of the view that you cannot gain propulsion on an AC72 from "pumping" the wing the amount they did.

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(in foiling, sheeting out causes the boat to rise and sheeting in pushes it down).

OK. Another possible thing that could be going on in "Beast Mode," as seen in a few videos.

 

Or "pumping," as some might say.

 

I remain certain that what we saw was as much to do with foil loading as anything else. Pumping is about propulsion and I also remain of the view that you cannot gain propulsion on an AC72 from "pumping" the wing the amount they did.

 

 

Might be worth you reading up on starting vortex and opposing motion to satisfy the requirement for conservation of angular momentum, before you get too attached to that view.

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I remain certain that what we saw was as much to do with foil loading as anything else. Pumping is about propulsion and I also remain of the view that you cannot gain propulsion on an AC72 from "pumping" the wing the amount they did.

I thoroughly agree that no propulsion was generated by the sheeting we saw in the videos. :)

 

It is the closest thing to the accusation of "pumping" that anyone has shown.

 

Just trying to develop an understanding of what value the trimming had--what the trimmer was trying to accomplish.

 

You've added some data to the mix. Thanks!

 

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And maybe it's the conflagration of 'Beast mode' and 'pumping' that is the root of any misunderstanding.

 

- It was explained in a recent link that the aptly named 'beast mode' was Oracle resorting, out of deperation, to a style of racing that they had initially rejected as unsustainable for the crew.

- The repeated movements of the sheet/traveller on the other hand appear to be connected with setting up on a new tack after a manouver and presumably with initiating foiling ASAP.

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At what boat speed can an A Cat start to foil? Also wind speed?

As with all foilers, it's different upwind to downhill. technique is all. Off the wind, you can fly with 7 knots of wind, although if you are really good, you will probably get airborne in a bit less. You are probably doing about 10 knots of boatspeed, but again, with technique, that can come down a bit. Upwind, because of the different loading of the foils, you need about 12 knots of breeze to be properly foiling and a bit more than that in boatspeed terms.

 

As said, technique is all. On Sunday, we had 5 foilers on the water with winds of no more than 10 knots and most of the time it was 7-8 knots, which fell away in the last hour on the water. 3 of the boats were regularly foiling downhill, until the breeze crapped out. The best 2 sailors got a little upwind foiling, but it was tough and there were only marginal gains on VMG. The other 2 sailors only got up a few times and for fairly short distances.

 

It is also hard to determine the exact boatspeed for takeoff, because you have to be fairly physical and time certain actions exactly. It's not as simple as with a plane, where you reach a certain speed and the wings are producing enough lift for take off. Because of the sideways loading on the foils, you have to have the technique of sheeting out and then back in at the right moment so as to unload the foils a bit and this helps the boat rise (in foiling, sheeting out causes the boat to rise and sheeting in pushes it down). So some without good technique probably need another 2 or even 3 knots fo boatspeed before their boat will foil.

 

The other factor is that different foils change the take off point very noticeably. A general rule of thumb seems to be that the earlier the take off speed, the slower the ultimate top end speed is. In addition, somke foils become pretty scary as they get up to top speed, so even though they might be both fast and capable of early foiling, they are just too unstable for overall good vmg round the course. There are also other trade offs which complicate the situation more.

 

In short, I think wind speed is far more relevant in predicting foiling than boatspeed. We are just about at the point of foiling downwind in most conditions we are race in, although on really light days, we cannot. Our class rules only allow for 1 set of foils for a regatta, so we always have a bit of a compromise.

 

Would a larger lifting surface have the same problem as the earlier take off foils section?

 

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And maybe it's the conflagration of 'Beast mode' and 'pumping' that is the root of any misunderstanding.

 

- It was explained in a recent link that the aptly named 'beast mode' was Oracle resorting, out of deperation, to a style of racing that they had initially rejected as unsustainable for the crew.

- The repeated movements of the sheet/traveller on the other hand appear to be connected with setting up on a new tack after a manouver and presumably with initiating foiling ASAP.

 

Point taken. Thanks for the clarification!

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Look into the effect of rapid but very small alterations in wind angle of attack, more specifically the accelerated flow over the leeward side of the wing, when AoA is rapidly increased marginally then returned to "default" setting, caused by the modification of the starting vortex.

Don't think pumping, more like rapid, repeated twitching.

Question: Have you ever examined a Hawk hovering in the sky observing its prey? It is not flying, but hovering, same wings but what is the bird doing differently?

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Question: Have you ever examined a Hawk hovering in the sky observing its prey? It is not flying, but hovering, same wings but what is the bird doing differently?

I was always led to believe that you couldn't use a bird as an example because the way their wings work are very different from the way sails and wing sails work. A bird has an ability to rapidly change the equivalent of camber, angle of attack, leach profile (variable twist) plus they have the ability to create their own wind by vigorous flapping. They can generate enough lift to support their hovering even on a day with zero wind. If you watch a video of a hawk hovering, you will see that they move their wings through a far bigger range of movements than we are talking about with the wing movement on OR.

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And maybe it's the conflagration of 'Beast mode' and 'pumping' that is the root of any misunderstanding.

 

- It was explained in a recent link that the aptly named 'beast mode' was Oracle resorting, out of deperation, to a style of racing that they had initially rejected as unsustainable for the crew.

- The repeated movements of the sheet/traveller on the other hand appear to be connected with setting up on a new tack after a manouver and presumably with initiating foiling ASAP.

What specific video footage can one find the repeated main sheet pumping on Oracle?

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Good grief, pumping has its own thread and there's zero new to say on the subject. Can those determined to flog this two-year old dead horse at least keep to thread dedicated to the subject?

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Good grief, pumping has its own thread and there's zero new to say on the subject. Can those determined to flog this two-year old dead horse at least keep to thread dedicated to the subject?

+1

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Question: Have you ever examined a Hawk hovering in the sky observing its prey? It is not flying, but hovering, same wings but what is the bird doing differently?

I was always led to believe that you couldn't use a bird as an example because the way their wings work are very different from the way sails and wing sails work. A bird has an ability to rapidly change the equivalent of camber, angle of attack, leach profile (variable twist) plus they have the ability to create their own wind by vigorous flapping. They can generate enough lift to support their hovering even on a day with zero wind. If you watch a video of a hawk hovering, you will see that they move their wings through a far bigger range of movements than we are talking about with the wing movement on OR.

 

Yes.

But, the bird is having to maintain lift of its entire mass, the foiling vessel only requires fractional but regular increased leeward wing air flow. This can be transmitted into increased forward motion. The amount of motion will depend on how well that energy is transmitted...which put really simply means for the same fluid resistance you get more speed. So the foils need to be engineered to take advantage of this, and the "mechanicals" engineered to provide for this "mode" almost continuously for an entire race. That sounds like "beast" mode to me.

Of course there is a hell of a lot more to this than what I have written above, obviously; however the team that can produce a controlled, continuous on demand wing "quiver" mode, will be faster to foil, and faster on foil.

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The team that can increase the "power" developed by the wing can reduce the foil hydro resistance to get the same hydro lift. Less resistance = more speed.

We may yet see the introduction of "wedge" style hydro foils, but most likely only with a commensurate increase in wing "power".

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But there's no point developing wing sails further, which is why they're OD, right?

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Question: Have you ever examined a Hawk hovering in the sky observing its prey? It is not flying, but hovering, same wings but what is the bird doing differently?

 

I was always led to believe that you couldn't use a bird as an example because the way their wings work are very different from the way sails and wing sails work. A bird has an ability to rapidly change the equivalent of camber, angle of attack, leach profile (variable twist) plus they have the ability to create their own wind by vigorous flapping. They can generate enough lift to support their hovering even on a day with zero wind. If you watch a video of a hawk hovering, you will see that they move their wings through a far bigger range of movements than we are talking about with the wing movement on OR.

Don, aerodynamics is aero dynamics!!!... it does not matter how a foil efficiently and effectively converts velocity of air over a surface and it does not matter how that surface is constructed or designed or how it's surface is finished. If it tests fast it is fast ( for the velocity of air that it is pushing through)... but it just be test correctly by professionals, in certified test beds... not a muppet with SA access, and a GPS!

 

Everyone. DO NOT BE FOOLED BY THIS BULLSHITTER SIMON. His design, testing procedures, and everything he's posts is based on club sailing a few A class cat with average sailors.

 

There is no design program, infinite analysis,correct test procedures, video analysis, lab/expert verification, !!!

 

 

It just a over inflated ego, with a GPS, and a view mates sailing A Class cats and comparing RANDOM DATA FROM DIFFERENT BOATS, FOIls, SAILORS, ....

 

 

If you read his posts you will see it is just absolute crap with no data or evidence to back it up!!!

 

If you read his posts... you are a bloody idiot!

 

I put doug Lord in the same category

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Good grief, pumping has its own thread and there's zero new to say on the subject. Can those determined to flog this two-year old dead horse at least keep to thread dedicated to the subject?

+1

+2...

 

It's the Doug, Simon, tornadocat bullshitters club.

 

If these guys are expertts?... then why are they here?

 

That are obviously bored with life and sitting nude in front of this PC's frothing of stuff they make up.

 

The AC thread is really just the Absolute Crap thread lead by three muppets!

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And maybe it's the conflagration of 'Beast mode' and 'pumping' that is the root of any misunderstanding.

 

- It was explained in a recent link that the aptly named 'beast mode' was Oracle resorting, out of deperation, to a style of racing that they had initially rejected as unsustainable for the crew.

- The repeated movements of the sheet/traveller on the other hand appear to be connected with setting up on a new tack after a manouver and presumably with initiating foiling ASAP.

 

What specific video footage can one find the repeated main sheet pumping on Oracle?

None! Pumping is defined under the rules and the AC kit cannot adjust the wing fast enough or with a big enough range of movement to create extra height or velocity.

 

But Simon will define this for you. He is the guru!.... not!

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That's pretty unfair. Muppets have a show worth watching...

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....... and everything he's posts is based on club sailing a few A class cat with average sailors.

You got to laugh at this guy. I love the description of the sailors involved as "average". I wish I was that average. I wish I had won 2 Olympic medals. I wish I had sailed at 3 different Olympics in 3 different classes. I wish I had been awarded ISAF Sailor of the Year. I wish I had won multiple world championships. I wish I had been paid to helm AC cats. Unfortunately, I am not good enough, but they are. Where I am fortunate is that they do consider that i am good enough to train with, coach and provide technical support for them.

 

I also wish we could do some club sailing, rather than continuous training and assessment. But as the troll suggests, you learn nothing from club sailing, so they train like the world class professionals they are.

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And maybe it's the conflagration of 'Beast mode' and 'pumping' that is the root of any misunderstanding.

 

- It was explained in a recent link that the aptly named 'beast mode' was Oracle resorting, out of deperation, to a style of racing that they had initially rejected as unsustainable for the crew.

- The repeated movements of the sheet/traveller on the other hand appear to be connected with setting up on a new tack after a manouver and presumably with initiating foiling ASAP.

What specific video footage can one find the repeated main sheet pumping on Oracle?

None! Pumping is defined under the rules and the AC kit cannot adjust the wing fast enough or with a big enough range of movement to create extra height or velocity.

 

But Simon will define this for you. He is the guru!.... not!

 

I was just skeptical about the pumping claims based on my wing sailing experience. The example Doug referred to me looks more like the trimmer is playing the hull ht much like one plays the traveler on a conventional soft sail rig. I do the same thing when I want to maintain a hike my winged dirtboat or iceboat.

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At what boat speed can an A Cat start to foil? Also wind speed?

 

It is also hard to determine the exact boatspeed for takeoff, because you have to be fairly physical and time certain actions exactly. It's not as simple as with a plane, where you reach a certain speed and the wings are producing enough lift for take off. Because of the sideways loading on the foils, you have to have the technique of sheeting out and then back in at the right moment so as to unload the foils a bit and this helps the boat rise (in foiling, sheeting out causes the boat to rise and sheeting in pushes it down). So some without good technique probably need another 2 or even 3 knots fo boatspeed before their boat will foil.

If this translates to the AC size boats then it seems the best explanation so far.

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Please Do Not look at the photo above and consider it to be sustained flight.

The jib is inside out and the traveller looks suspiciously pulled to weather......

 

As cool as the instantaneous picture suggests - my bullshit meter is deep in the red zone - exactly in the same way that a certain fellow from floriDa always presents his moments of launch captured as a picture as being that of proof that his designs are successful.

 

I suspect that the boat was towed into this situation by the Rib that the picture was taken from........

 

Video (unedited and complete) is really the only way to prove that this sort of behaviour is possible.

The closest of which I can recall is C class cats in Swiss lakes doing their thing in impressively calm conditions - but remember that those boats have much greater power to weight properties than any production foiling boat (such as the one above) can hope to achieve, and 4 knots is such an arbitrary measure - surface, masthead or 10m altitude - gust, lull or steady - you get my drift.

 

At the end of the day flight by model planes and the like can be achieved at very low velocities. Think walking speed inside a hangar.

But most real pilots want to go faster than that.....

 

Look at the complexity (not to mention cost) that is required for a 747 to change its wing profile and camber from cruising speed to landing speed (again not an ultimately sustained activity - it eventually just allows this big heavy object to land on reasonably short runways and still stop) and then extrapolate this into sailboats and you begin to see how and why Moth sailors have different sized (and profiled foils) for different conditions.

 

Or if you want another comparison - think about the ebb and flow of how the Monaco grand prix was won at the weekend.

An F1 car can't run in the wet on Slicks and expect to win.

Nor can it strap on Extreme Wets and expect to run fastest lap times in the Dry.

But ultimately you can have a fast chassis, fast driver and new improved powerful engine, but if you aren't going to have a set of tyres ready to bolt on during a scheduled pit stop - you will finish second.

 

Variables, complexity and the interweaving compromises that result, dictate the overall sum of their parts. This is a massive part of our sport.

 

For myself, hydro foiling is of great interest.

Sailing is of great interest.

But generally, sailing in 4 knots of breeze is of considerably less interest.....

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Yep, I had noticed the jib and the main, however we do not see the waves of a motor boat ahead.

I would agree it was on a short period of time with a lighter boat and foils optimized for light wind.

An ultralight lifts at smaller speeds than a 747...

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At what boat speed can an A Cat start to foil? Also wind speed?

 

It is also hard to determine the exact boatspeed for takeoff, because you have to be fairly physical and time certain actions exactly. It's not as simple as with a plane, where you reach a certain speed and the wings are producing enough lift for take off. Because of the sideways loading on the foils, you have to have the technique of sheeting out and then back in at the right moment so as to unload the foils a bit and this helps the boat rise (in foiling, sheeting out causes the boat to rise and sheeting in pushes it down). So some without good technique probably need another 2 or even 3 knots fo boatspeed before their boat will foil.
If this translates to the AC size boats then it seems the best explanation so far.

Foiling in 4 kts of wind. Will the ACC boat do better ? not sure.

20019223314044579222.jpg

And with the jib flapping and not full!!!... nice photo shop job girls

 

And the deception continues.....

 

Keep digging girls

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Yep, I had noticed the jib and the main, however we do not see the waves of a motor boat ahead.

I would agree it was on a short period of time with a lighter boat and foils optimized for light wind.

An ultralight lifts at smaller speeds than a 747...

You are not credible. To post that photo making out that this boat is foiling in 4 knots of breeze just proves that you are the leader of the bullshitters club!...

 

You, Simon, and Doug bring this thread and the sport into disrepute with all this bullshit!...

 

You three culprits have put so many people off the AC by virtue of you continued lies and bullshitters!

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....... and everything he's posts is based on club sailing a few A class cat with average sailors.

 

You got to laugh at this guy. I love the description of the sailors involved as "average". I wish I was that average. I wish I had won 2 Olympic medals. I wish I had sailed at 3 different Olympics in 3 different classes. I wish I had been awarded ISAF Sailor of the Year. I wish I had won multiple world championships. I wish I had been paid to helm AC cats. Unfortunately, I am not good enough, but they are. Where I am fortunate is that they do consider that i am good enough to train with, coach and provide technical support for them.

 

I also wish we could do some club sailing, rather than continuous training and assessment. But as the troll suggests, you learn nothing from club sailing, so they train like the world class professionals they are.

Keep wishing Simon.

 

You may be sailing againsta couple of good guys but your theories and testing is flawed.

 

If these other guys are so good then why are they not on the team.?

 

Also winning a Olympic class means nothing in the foiling world.... after all - Name a olympic class that has two hulls and foils!!!

 

Simon, I think they are laughing at YOU!... except your two mates here who have also dug themselves into a deep hole!

 

Suggest you take a break so people can get some fresh air and you can regroup from all the bullshitting....

 

 

Unless.... you can produce valid data, video, GPS and Wind data, validation of test results, photos. Foil design References, shape designers name, the people involved!

 

Little league Simon!... little league

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"An ultralight lifts at smaller speeds than a 747..."

So what?

 

How is this a helpful comment in any way shape or form????

 

FFS, this is the sort of meaningless crap that has demeaned this forum.

 

My post was to discourage use of bogus photos as "evidence" and to remind everyone that design choices have both limitations and compromises.

 

You want early take off - fine, but your top speed will be limited.

You want higher top speed - again fine - but do not be expecting low velocity lift off.

 

So if you want a boat that lifts out at 4 knots TWS - great - but do not expect the same configuration to be competitive against those designed to be optimum at 12 knots TWS.

 

Those syndicates who can find the best cross over between their different sets of foils and then race them in anger without suffering touchdown in transitions will be the winners. Its as simple Complex as that.

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The fact is foils can be designed to allow early take off and still have high top end speed. Surface piercing foils and uptip foils can have designed-in twist so that there is high lift at low speeds and when the foil speeds up the high lift portion clears the water. Wand based foils can be designed specifically for low speed takeoff while allowing high top end because the automatically increase RM as required. The idea is that manufacturers like Quant boats and Whisper want to try as much as possible to allow the whole wind range to be used for what the boat is designed for: foiling! The day is past where a production foiler can foil only when the wind is over 10 knots........

And the AC guys are already using interchangeable tips for their UptiP foils and that could allow a drastic improvement in low speed takeoff for the venues they select where the wind is light. Whatever it takes to get those boats foiling when they're racing is an investment in the future. Seeing a bunch of "high tech" foilers seahugging is just ridiculous.

 

A 23' foiling keelboat takes off in under 5 knots-by design:

Note- a nearby rib measured 3.4 knots at two meters off the water when this shot was taken. The 23 began to foil before a nearby foiling A Cat and Moth.......

 

2dj6kir.jpg

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You're welcome, Bob......

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There is no design program, infinite analysis,correct test procedures, video analysis, lab/expert verification, !!!

 

 

Something new?

 

Does that replace finite element analysis then?

 

 

 

 

That's pretty unfair. Muppets have a show worth watching...

 

Each program was longer than the ACWS NY - and had better commentators!

 

hqdefault.jpg

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There is no design program, infinite analysis,correct test procedures, video analysis, lab/expert verification, !!!

 

Something new?

 

Does that replace finite element analysis then?

 

 

HaHa .. I wondered if anyone would pick that up .. :D

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Aerodynamics is aero dynamics!!!...

 

If it tests fast it is fast

Everyone. DO NOT BE FOOLED BY THIS BULLSHITTER

There is no design program, infinite analysis,correct test procedures, video analysis, lab/expert verification, !!!

 

If you read his posts (Simon)... you are a bloody idiot!

 

I put doug Lord in the same category

 

:lol:

 

Thanks for your constructive input in the thread, you and your suck puppets.

 

Are you the new Swallower of the forum ?

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Foiling in 4 kts of wind. Will the ACC boat do better ? not sure.

20019223314044579222.jpg

And with the jib flapping and not full!!!... nice photo shop job girls

 

And the deception continues.....

 

Keep digging girls

 

The image is from sometime before December 2013, it's been seen elsewhere. I have no doubt it's real, however the circumstances need some explanation. Does this modified F–20 really have enough sail area that it requires 2 on the wire with main and jib in only 4 knots of breeze? They may have been towed up and are seeing how long they can sustain foiling. Some of the leeward lines aren't hanging the way I'd expect.

 

There's a thread on pressure-drop.us (http://www.pressure-drop.us/forums/showthread.php?3595-Foiling-In-4-Knots&s=846efa92b7064bc2a9e33bb0ddf43987).

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A 23' foiling keelboat

I'm not sure that a scow with a 60kg bulb is correctly described as a "keelboat". It's certainly an interesting lake boat.

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There is no design program, infinite analysis,correct test procedures, video analysis, lab/expert verification, !!!

 

Something new?

 

Does that replace finite element analysis then?

HaHa .. I wondered if anyone would pick that up .. :D

Haha .... wow! You picked up a spelling mistake but do not refute the whole post!...

 

 

Keep digging girls!.... you guys are full off it!... this thread Is just the right place for you!

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