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These boats are rocking.

I just wonder why, not limitated by rules, they chose to rack the main foil instead of using a flap at the edge, it seems much more efficient and easier to control.

Are they allowed in the AC62 rule ? I'll have to check.

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The longest the boat flew was 15 seconds with perfect pitch stability and a small roll due to the quartering waves she was going thru. You can look at some other RC foilers and be hard pressed to see 15 seconds of stable foiling. But the day we shot the video the boat would have kept on foiling all day if we had the time. the foil system worked perfectly allowing the boat to foil in a 5mph(not knots) wind. She flew on port and stb tack and even slightly foiled going upwind. I need help to sail this boat and get video and my crew is a high school coach so we may not get any more video until April or May. From what I saw in the video with the main screwed up and only delivering about 50% power in very light air I believe the boat will gybe on foils and maybe even tack on foils.

This is the first time any foiler foiled using two different altitude control systems at the same time. She is a remarkable boat and they'll be a lot more video in 2015.

This page has a detailed analysis of what went right and wrong in the Fire Arrow development including all the videos and the long and short versions of the foiling videos: http://www.boatdesign.net/forums/multihulls/high-performance-mpx-foil-self-righting-trimaran-test-model-36058-124.html

 

 

 

 

2 issues to write about.

After looking at DL's videos of the model sailing, there is a problem. Either there is a hidden video that i didn't see, or there is no proof the the "model" foils with stability. There needs to be, in my opinion, at least 60 seconds of stable foiling on video to claim on a forum that the boat is a successful foiler. All i saw was potential; a creation that looked to have quite a bit of drag showing that it could possibly be a foiler with some tuning and driver learning. It is supposed to be a scale model, but the rig is an rc rig and prolly wouldn't work very well if scaled up. Also there is the claim that the foils are Pete Melvin inspired, but the tips are clearly pointing down after that reverse curve was added. The ac72 foils are well described as L/V. The L has a rounded corner and is less than 90 degrees, but if you lean an L over, the tip points up. I think the idea is to not lean the L as much on the light upwind legs so that it is just a regular daggerboard with a end plate. Z boards don't look like a Z, S boards don't look like an S, and L boards don't look exactly like an L. Which brings up the second subject.

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2 issues to write about.

. It is supposed to be a scale model, but the rig is an rc rig and prolly wouldn't work very well if scaled up. Also there is the claim that the foils are Pete Melvin inspired, but the tips are clearly pointing down after that reverse curve was added. The ac72 foils are well described as L/V. The L has a rounded corner and is less than 90 degrees, but if you lean an L over, the tip points up. I

 

The rig is not an "RC" rig -a similar version with peaked up square top and square top jib was used once before on my 16' full size foiler. The difference with this rig is that it used a 7% wing mast with a "noggle" to automatically control mast rotation with respect to the boom. It also used a modern version of a gaff that allows control of the upper third of the sail with an adjustable upper outhaul. I didn't have it set up well on the day we foiled but all the little problems discussed on the page I linked to above have hopefully been solved.

As to the foils: they are most definitely TNZ inspired and whats more they worked perfectly, exhibiting the kind of altitude control that made these foils famous to start with. They are not a copy of anyones foils-they are my own- designed specifically to work well and not require any adjustment while the boat is sailing. Again, they worked absolutely perfectly. See photo "A" below which shows the main hull seahugging and the ama flying about three inches above the surface. Then look at "B" and the main hull is now flying with the ama altitude just the same. In other words, the UptiP foils maintained the same altitude at two different speeds and with two different load cases.

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2 issues to write about.

After looking at DL's videos of the model sailing, there is a problem. Either there is a hidden video that i didn't see, or there is no proof the the "model" foils with stability. There needs to be, in my opinion, at least 60 seconds of stable foiling on video to claim on a forum that the boat is a successful foiler. All i saw was potential; a creation that looked to have quite a bit of drag showing that it could possibly be a foiler with some tuning and driver learning. It is supposed to be a scale model, but the rig is an rc rig and prolly wouldn't work very well if scaled up. Also there is the claim that the foils are Pete Melvin inspired, but the tips are clearly pointing down after that reverse curve was added. The ac72 foils are well described as L/V. The L has a rounded corner and is less than 90 degrees, but if you lean an L over, the tip points up. I think the idea is to not lean the L as much on the light upwind legs so that it is just a regular daggerboard with a end plate. Z boards don't look like a Z, S boards don't look like an S, and L boards don't look exactly like an L. Which brings up the second subject.

The GC32. As mentioned before Martin Fisher designed quite a machine there. The version 1 had the S board system that he designed for the A class. It seems like there were hopes that that system would fully foil, but it turned out to be a skimmer. GC32 Version 2 has L/V with T rudders. i think there was an interview were they said that the boards were nearly the same size as an ac 72 board. Boards from a boat over twice it's size. It foils really well, but they still use the reacher off the wind even in force 4 with a reefed main. Here is a helmet cam vid from the 2014 race in France showing that. There is text at the bottom saying the boat is trickle down from the AC, (6:40 aprox) so its a relevant vid, and i think pretty exciting.

 

The guys were using a code 0 in that vid and a reefer main because the wind had dropped off since the start of the day and the race committee had mandated reefer mains.

 

Normally the GC32 goes downwind with only main and jib from about 12-14kts wind

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Great-thanks!

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With the ACWS 45's being modified to permit foiling, will the Speed Trial be restored to the competition? The prospect of a 45 balanced on all three at 30 knots or more and the crew effort needed to maintain the balance would make for some exciting imagery. Hopefully folks drawn to watch this part of the event would return for the next series of actual races.

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Well, the GC32 is designed to be easy to sail and fast-reduced heave stability on the 45 would probably translate to more spreed, But that's not a given: Groupama had high heave stability and was much easier to sail than its principal rival Hydros -who was faster but harder to handle- Groupama won. On a 45 with more crew you might be able to get closer to the edge....

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Well, the GC32 is designed to be easy to sail and fast-reduced heave stability on the 45 would probably translate to more spreed, But that's not a given: Groupama had high heave stability and was much easier to sail than its principal rival Hydros -who was faster but harder to handle- Groupama won. On a 45 with more crew you might be able to get closer to the edge....

Theoretically the AC45 should be faster because longer, wider, a wing and controls allowing smaller foils with less uptips.

That said I would love to see the GC32 going faster which would prove, like GPMA, that simple solution are faster, but i don't think it will happen.

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^ GC32 vs AC45F - what chance they'll ever line up in the same conditions?

 

(There was a designers estimates for the 62s posted somewhere here yesterday (?) - suggesting 30kn upwind and 50kn downwind!)

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TC, here is the follow-up comparison between the two. What I'm looking forward to is a race/comparison between the Whisper and either the Nacra or Phantom or both-wands vs UptiP foils-what a story that will be!

http://www.catsailingnews.com/2014/05/nacra-f20-fcs-vs-flying-phantom.html#more

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Holy shit!

 

I was looking for the sailor. Not on the boat or nearby in the water.

 

Takes flying to a whole new level - can't imagine that's a very secure feeling.

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If that really was foil ventilation there may be a big problem with that boat... Check out the few seconds of single handed foiling-boat flying really high just before the double-handed crash footage.

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I have often been flying but never that high, boat must have been going pretty fast. If the foil cavited it shows how brutal the pp may be. Let's hope it won't happen with AC62 at 50 kts !

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I have often been flying but never that high, boat must have been going pretty fast. If the foil cavited it shows how brutal the pp may be. Let's hope it won't happen with AC62 at 50 kts !

Wow. 50kts. Really? What was the AC72's top recorded speed? 47.6 knots, IIRC.

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Some predict 30 kts upwind and 50 downwind.

 

Nothing strange as in the last races AC72 were on a regular basis at 27 kts upwind and 44 kts downwind.

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Sailing an A cat in strong conditions shows how good Mjscha Heemskert is.

It also shows how difficult it is to foil with Z boards in a choppy sea, much different than the previous video we saw.

 

https://www.facebook.com/video.php?v=10152970793372958&set=vb.667767957&type=2&theater

 

Man, he's good! The missing words could be: " altitude control system".........?

-------------

 

PS- the foil would not have "cavitated" but it might have ventilated-big difference. Or something could have let go? Cavitation is unlikely before the mid to high 40's depending on the foil design.

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Sailing an A cat in strong conditions shows how good Mjscha Heemskert is.

It also shows how difficult it is to foil with Z boards in a choppy sea, much different than the previous video we saw.

 

https://www.facebook.com/video.php?v=10152970793372958&set=vb.667767957&type=2&theater

He looks really good. It does seem that most A Class races are in flat water. Nothing flat about Santa Cruz. Wintertime is the best surfing there

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Sailing an A cat in strong conditions shows how good Mjscha Heemskert is.

It also shows how difficult it is to foil with Z boards in a choppy sea, much different than the previous video we saw.

 

https://www.facebook.com/video.php?v=10152970793372958&set=vb.667767957&type=2&theater

He looks really good. It does seem that most A Class races are in flat water. Nothing flat about Santa Cruz. Wintertime is the best surfing there

Amazing to see the work he does on the wire.

More interesting is to notice that 4 foils are not really that stable in waves, it would have been interesting to compare with 3 foils ( L + 2 rudder foils)

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I'm sure this is wrong - but here goes. It looks like it needs both foils and rudders immersed to start foiling - makes sense for a 4x4 right? So as long as the WW hull and foil is out, he has little chance to lift the leeward hull clear of some of that wave action.

 

TC can you say this is simply the difference between flat water and lumpy when there are a heap of setting and foil variables possible, not to mention more or less gusty etc?

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I'm sure this is wrong - but here goes. It looks like it needs both foils and rudders immersed to start foiling - makes sense for a 4x4 right? So as long as the WW hull and foil is out, he has little chance to lift the leeward hull clear of some of that wave action.

 

TC can you say this is simply the difference between flat water and lumpy when there are a heap of setting and foil variables possible, not to mention more or less gusty etc?

Only Mischa could answer about the settings but I doubt he would chose deliberately the wrong ones.

For the rest I was thinking of the same explanation you give: if the Z foils need the 4 foils in the water to foil stable it is easy on flat water while impossible in a sea with waves and puffs. So I don't think Doug's explanation is the right one here, an altitude control system would not help much.

 

That would mean a huge advantage for the 3 foils systems that would be more reliable in difficult sea. On the other hand Bermuda will have very calm water. I still think AC 62 will have 3 foils but don't think 4 is already excluded.

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Or: learn to overcome your training by keeping both hulls down until both lift out??

 

Keep it flat, keep it flat, etc.....

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By "altitude control system" I was referring to wand controlled foils(3down best but 4 down* too) and UptiP foils(3down) either of which would have handled those conditions better.

 

* as long as it didn't bottom out.

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Event flat I think it's impossible to have a steady windward lift on choppy water, it would be interesting to ask MH though.

Yes. I think he was foiling beautifully. Imagine an AC72 trying to foil in a proportionate sea state - like Molokai channel perhaps - can't believe it would look any steadier.

 

Interesting point about needing all four down to fly. The A class has a tight restriction on horizontal foil area. So they are a bit lift challenged to start with.

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Event flat I think it's impossible to have a steady windward lift on choppy water, it would be interesting to ask MH though.

Yes. I think he was foiling beautifully. Imagine an AC72 trying to foil in a proportionate sea state - like Molokai channel perhaps - can't believe it would look any steadier.

 

Interesting point about needing all four down to fly.

I think, perhaps wrongfully, that with 3 foils the lift is bigger on the main foil, thus providing a more stable flight in rough sea conditions. So yes I think an AC72 with comparable conditions would behave better.

It looks like Mischa tries to fly when bearing off but it is just not enough to fly.

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Actually this video is good news. The cat does not pitchpole but falls down in the water and brutally stops, the crew flies still attached to the wire and makes it captsize. That means that if the crew had had a chicken line the cat would probably have been able to recover, exactly like TNZ did when they rounded a mark at 40 kts.

Good news because it means that foilers are safer even when their foils fail, instead of pitchpoling, they stop brutally and sometimes lose crews (as it happened with TNZ too)

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Scoop!

 

Foiling in the Olympics!

 

Here's a short clip of where the downwind development is heading. Have loads more footage but can't give away much right now as I'm sure you understand.

 

The 17 rudders are a bit archaic in design and don't load evenly through the speed ranges. Its seem's the right settings are always just a compromise of feel between upwind and downwind.

 

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americas+cup+australian+concept+sketchbo:lol: - Aussies deserve a go. They'll need to shove the scheming $illionaires out of the way first though

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My goodness, it's not safe to post this stuff in a thread next to Doug Lord's posts!!!

 

americas+cup+australian+concept+sketchbo:lol: - Aussies deserve a go. They'll need to shove the scheming $illionaires out of the way first though

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Looking at the head of the wing, looks like it cants the head of the jib windward, wonder if they ever did any actual tests on this idea.

 

or

 

being trolled right now.

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Wohoo FP! thief!

 

NZ Design

 

Sweet machine, nice wing, but a Tri - so maybe not for AC35....??

 

Codys+first+racer.jpg

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What sort o' boat ya got?

A red one.

Cool.

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Event flat I think it's impossible to have a steady windward lift on choppy water, it would be interesting to ask MH though.

Yes. I think he was foiling beautifully. Imagine an AC72 trying to foil in a proportionate sea state - like Molokai channel perhaps - can't believe it would look any steadier.

 

Interesting point about needing all four down to fly. The A class has a tight restriction on horizontal foil area. So they are a bit lift challenged to start with.

 

I have sailed small boats and big ones in heavy trades in the Molokai Channel. It ain't no picnic out there. The swells are so big that when a little/medium sized boat goes into a trough, the wind just about stops. Guess what happens 15 seconds later at the top of the next swell? WHAM! This means very difficult foiling.

 

We were sailing out there in 1969 racing the Transpac finishers coming around past Molokai, then CocoHead and approaching Diamond Head when one of the early finishers (Blackfin?) lost her mainmast with its giant chute, and finished the 2300 mile race going backwards under a little chute on the mizzen!

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Word is that some A Class sailors are raising the weather board - and flying on three foils.

 

But sticking just three foils in the water already has a solution.

 

I'm not certain - but I think the following boat might might be a legal A Class (or close - it's shorter) other than its TNZ style foils:

 

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Thanks for the video. More on this boat here: http://forums.sailinganarchy.com/index.php?showtopic=162225

But Simon N said it's not practical to raise the windward foil on a singlehander. Just another gem from him.......

This boat uses a cut down A Class rig and is 15.5' long......and a "garage foiler" according to catsailingnews but with a top builder doing the garage work.

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but Simon N said it's not practical to raise the windward foil on a singlehander. Just another gem from him.......

Doug

 

Instead of trying to score points, how about you actually go sailing and do something worthwhile? And instead of twisting my words, how about attempting to understand the issues. I never said it couldn't be done but simply that the amount you lose in doing it was too great.

 

Having spent a long time working out how to raise the windward foil and drop the other one in A's, I can tell you that it is both difficult and time consuming and from both the results and conversations with those at the front of the fleet at the A's, I am beginning to think that factor alone is going to influence foil design - if we can find a compromise foil that doesn't need lifting upwind but is either as quick or close to the downwind performance of the ones that do need to be lifted, we will see significant gains. I should add that is based on sailing experience and trying to work the problem out with some of the best A Class sailors out there. Maybe we will end up with systems that mean we can tack almost as fast as those not raising boards, but we are a long way off and I believe we are better off trying to find how to make the boards work with both down.

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Perfect conditions but amazing speed and stability. The other boat seems to be an Nacra F20.

It would be interesting to compare with a 4 foilers now and in tougher conditions

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Interesting - or even fascinating - is the key word here. Looks like the Aussie A Class WC's are not being dominated by any particular board shape.

 

Lots of letters in the mix: Z, J, and C still there. They have some breeze though so I guess the straight boards are finally out to pasture.

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Several months ago Bailiscus replied to my suggestion that the AC62's might foil on four points. When made to balance on two foils and twin rudders the boat's structure must absorb the torque that results from wind direction, velocity and the camber of the wing. As I recall his argument, these forces cannot be made to balance when two foils provide lift. The foil that provides righting moment will work against the foil on the windward side. No amount of trimming will work to offset continuous changes in lateral and vertical forces . The structure will twist to failure or it will be so heavy as to render the structure inefficient for racing. Is the four-point stability we've seen in the video unique to small, light boats?

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It's possible to have two main foils developing vertical lift but there is a big difference between that and the same configuration with the windward main foil developing downforce similar to the systems on the Hobie trifoiler, Rave and Osprey. The surface sensors(feelers on the Hobie,wands on the Rave and Osprey) on all three are independent of each other and can therefore react to the boat heeling by causing the windward main foil to create downforce. On those boats the forces are huge and the RM(righting moment) developed by the foils can exceed the structural strength of the boat. A boat using such a foil system has to be built like a tank to take the loads but at least the crew can sit in the center.

As best I can tell, having two main foils developing vertical lift can be counterproductive ,reducing the effective righting moment of the boat. Some guys set the AOI(angle of incidence) of the vertical lifting portion of the windward foil to zero(or lower depending on the type of foil) going upwind. They could, theoretically, manually adjust the AOI of the windward foil to develop downforce increasing RM-but they have to be damn careful because the loads can get excessive if the boat is not designed for it.

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Several months ago Bailiscus replied to my suggestion that the AC62's might foil on four points. When made to balance on two foils and twin rudders the boat's structure must absorb the torque that results from wind direction, velocity and the camber of the wing. As I recall his argument, these forces cannot be made to balance when two foils provide lift. The foil that provides righting moment will work against the foil on the windward side. No amount of trimming will work to offset continuous changes in lateral and vertical forces . The structure will twist to failure or it will be so heavy as to render the structure inefficient for racing. Is the four-point stability we've seen in the video unique to small, light boats?

 

It's certainly true that the windward foil works against the leeward foil - it reduces the righting moment and it typically produces a side force to leeward. However, these same factors can give stability to the two-foil system. And while the loss of righting moment is significant, it may not be fatal if the drag is reduced such that it doesn't take as much power to drive the boat. When I started to look at A-class foils, I was surprised to see how well the C foils worked compared to the L foils, and that more anhedral (which I expected would be less efficient) was actually a good thing.

 

There are so many interacting elements in a foil system that I don't think one can just look at a configuration and apply simple arguments to it. I think you have to run some numbers or get actual experience with it to know how it really works.

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Actual experience - that's what we're after!

 

If Spithill can't exploit an entire America's Cup design team to build a custom A Class solution - then what good is it?

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Actual experience - that's what we're after!

 

If Spithill can't exploit an entire America's Cup design team to build a custom A Class solution - then what good is it?

or... how good is he?

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^ apart from using hydrodynamic forces on a 'L' foil to provide variable lift (= additional RM in this case) and to counter leeway you mean?

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^ apart from using hydrodynamic forces on a 'L' foil to provide variable lift (= additional RM in this case) and to counter leeway you mean?

 

No ,what I mean is that an AC UptiP foil uses leeway to increase lift, where the BP foil appears to have a loss in lift due to leeway,unless I'm missing something.

When the BP boat is more or less level the foil would work more or less like DSS with a wingtip and all the pressures would be right. As it heels,though things change as per my sketch:

post-30-0-11678800-1421426126_thumb.png

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So we now have diagrammatic proof that DL does not know what he is talking about.

 

A diagram showing an L-shaped foil (basically a DSS foil with endplate) - but managing to generate high pressure on its top surface. :blink:

 

Which is the complete reverse of what DSS and these boards actually do.

 

Douche looP you have proposed a system that reduces RM and Stability.

 

Idiot.

 

Remember the law of physics where high pressure flows to fill a lower pressure or vacuum.

The actual system proposed by VPLP has a hybrid of DSS, combined with their curved dagger boards that they have for years mounted through the hull.

 

This new variant places their dagger boards - to all intents and purposes - on the tip of the Hybrid DSS board - thereby moving its lift capability further out on a longer lever arm (the DSS board) - than if it had stayed mounted in the hull.

 

There is also the multiplier effect of not only lengthening the lever arm between keel bulb (canted out to weather) but also creating a dihedral effect between the horizontal element and the end plate dagger board element.

 

That is to say that as heel increases the vectoring of the two lift forces combines to counter both heel and leeway - but in a much more powerful solution than if the two elements have remained unattached. e.g WOXI.

 

The dihedral effect will also create a negative feedback loop to allow the boat to find a balance point of heel - which will probably be also the same point that these wedge shaped hulls are actually sailing on relatively small waterplanes (or WSA) and the keel is acting almost at horizontal - a position of maximum possible power under the current rules.

 

There's a lot going on in these boats and to disregard the effects of Hull shapes, keel, rig and a thousand other details is clearly beyond the capabilities of most of us here - that includes me, and certainly includes DL aka WoPoO (Wolf Pack of One).

 

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Sketch 1 below shows that as the boat heels that leeway will cause the flow to impinge on the upper side of the larger foil resulting in a reduction in angle of attack(depending on the AOI(angle of incidence) of the board relative to the hull and the degree of leeway). The further the boat heels the more likely the larger foil is to lift down and to windward. At the angle shown it could go either way.

Sketch 2 shows the the pressure distribution as the boat becomes more level, where the larger portion of the foil begins to lift vertically and to leeward.

The Lift Vector sketches show the direction of lift with the different pressure distributions. You can see the direction the boat moves due to leeway and that will, unequivocally, change the lift on the larger portion of the foil depending on angle of heel and degree of leeway.

It should be 100% clear that the pressure distribution can change depending on angle of heel. Further, when the change results in high and low pressure on the same side of the foil(top left below-1st sketch) there is lots of drag:

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post-30-0-66813600-1421598167_thumb.png

post-30-0-74543000-1421598193_thumb.png

post-30-0-68883300-1421598222_thumb.png

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GC32s take on Key West, while various ex AC types help out on the monos

 

KEY WEST, Fla. (AP) — Two-time Rolex Yachtsman of the Year Terry Hutchinson will call tactics for Bella Mente during the five-day Quantum Key West sailing regatta that begins Monday off the Florida Keys.

Owned by Hap Fauth, the 72-foot-long Bella Mente will defend its 2014 IRC 1 victory against Shockwave, steered by George Sakellaris with tactician Paul Cyard, as well as Numbers, skippered by Gunther Buerman with strategist Brad Butterworth.

Race organizers say 115 boats are divided into 10 classes. The J/70 is the largest with 54.

A new class this year is the Great Cup 32s. Officials say with America's Cup now being contested in catamarans, the popularity of multi-hull racing has soared. The GC32s can go as fast as 50 knots and crewmembers wear helmets.

 

http://www.chron.com/sports/article/Quantum-Key-West-sailing-regatta-begins-Monday-in-6023814.php

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I've heard 36, but not 50 knots-anybody hear of a GC32 doing 50?

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Sketch 1 below shows that as the boat heels that leeway will cause the flow to impinge on the upper side of the larger foil resulting in a reduction in angle of attack(depending on the AOI(angle of incidence) of the board relative to the hull and the degree of leeway). The further the boat heels the more likely the larger foil is to lift down and to windward. At the angle shown it could go either way.

Sketch 2 shows the the pressure distribution as the boat becomes more level, where the larger portion of the foil begins to lift vertically and to leeward.

The Lift Vector sketches show the direction of lift with the different pressure distributions. You can see the direction the boat moves due to leeway and that will, unequivocally, change the lift on the larger portion of the foil depending on angle of heel and degree of leeway.

It should be 100% clear that the pressure distribution can change depending on angle of heel. Further, when the change results in high and low pressure on the same side of the foil(top left below-1st sketch) there is lots of drag:

Lordy, Lordy, Lordy - what a complete surprise.

 

Your Bafoonery, Ineptitude and Shame know no limits.

 

Instead of putting your hands up and admitting your error you try to bluster your way out of it with terminology that might confuse a non-sailor or child but it hides nothing.

 

Lets set out the parameters that apply to your stick drawings:

1. It is a rudimentary cross section through an IMOCA60 hull as depicted in the VPLP media release of last week and as shown in Post 663 - Thanks Xlot

2. Your stick drawing shows the hull and new DSS Hybrid Dagger Board - but does not show the keel - no problem - but because of post 663 and your drawing both showing the foil to the right hand side (port side of boat) the bow must be coming at you when you refer to your stick drawing - agreed? (I know I forget myself somethimes - we are dealing with Doug Lord - where white can be black etc etc.......)

3. In the last edition of the Vendee Globe - the winning IMOCA 60 - Macif - had an average speed over the course of 15.3 knots (for a track of more than 28,000 nautical miles)- it is unlikely that VPLP would win a commission to design a slower boat than this, so lets just say that this design is doing 15.31 knots of boat speed out of the screen at you, as a reader. Happy? of course your not - you are in the middle of a revolution - and we know what happy and fun filled events they are - just ask any citizen of a country in revolution - that's a lot of central Africa, for those stuck in Florida.

4. Your original stick drawing in post 667 shows the foil as being of two surfaces, with an elbow in the middle - the first surface from hull to elbow, the second surface outside of the elbow - you label your drawing that the upper surface of the first section and the lower surface of the second section will both be areas of high pressure - which is not possible - surfaces that are designed to do as you describe will, if unrestrained - Spin - rather like a rudimentary propeller - but as this is restrained - it would just create turbulence and drag - something that real yacht designers of great talent do not do - VPLP included.

 

Now re-do your vector diagrams Properly.

Hint - each surface can only generate ONE direction of primary force (whose strength is represented by the length of that line...... remember these details now WoPoo???); these can then be linked to give a resultant force - Your lift vector explanation in post 669 is a full grade 3F - Failed, F@cked and Foolish - in your explanation of your first diagram, you attribute both surfaces with two forces - but no resultant force - in your second explanation you get better - but you still have two forces coming out of the second surface section - before showing a resultant force.

 

Back to entry level physics for you WoPoo.....

 

Over on Boat Design in the parallel thread to this one, you wrote on the 16th Jan:

"When the boat heels with the BP foil there is definitely high and low pressure on the same side of the foil due to leeway causing high pressure on the portion of the foil closest to the hull while the uptip portion has low pressure on the inboard side and high pressure on the outboard side."

 

So even if you try to weasel your way out of what you have drawn - you still state in writing your belief that the foil will generate high and low pressure on the same side (which for those that do understand, will just combine in favour of whichever is largest e.g +60 and -50 actually just leave +10 or +70 and -70 results in zero, and so on)which results in reduced RM and Stability - which is what I hauled you up on in the first place.

 

The only way your original drawing could be close to realistic is if this boat is going sideways at say 4-5knots with 0.00 knots of forward motion. (Though if this were happening then something has gone really wrong.....)Only by drifting sideways at considerable pace could you get flow across the top surface of the first section to generate a localised high pressure area - and even then it would in the downwash of the second suface - which if it was going sideways with no forward motion - would still generate localised high pressure on its underneath surface (and a localised lower pressure on its upper surface) - so the resultant force would be turbulence and drag - exactly what would be seen when a hull and surfaces gets dragged sideways. Remember that an average speed of this boat is 15.31 knots - sometimes slower - sometimes a lot faster - the vector change of leeway even at 15 knots would be very small - certainly not enough it induce low pressure on the upper surface - reduce it by a percentage point or so, granted, but not enough to reverse the dihedral effect - remember these foils are asymmetric - and are designed to create upward lift.

 

Take for instance in your reply of post 669 you wrote:

"The further the boat heels the more likely the larger foil is to lift down and to windward."

 

Seriously, you cannot read that statement 10 times and still take you seriously.

Use the term Lift - and it is only associated with upwards direction - yet you talk about lift down - also more commonly called down force - but yet also to windward. Designers tend not to want to make their craft artificially heavier - with all the extra drag that weight creates. But somehow you also managed to twist the force into a windward moment.

 

There is no scenario that if the boat had any appreciable forward motion that any foil could do as you describe (even with error strewn pressure diagrams or misleading Vector Drawings).

 

The Foil is designed as a Dihedral element - the two surfaces generating lift which will lead towards an overall resultant force - Small immersion (where the second surface may actually stick out and above the water surface) and the first surface does all the heavy lifting - much like a DSS foil would.

 

Then as heel increases, through say a gust - there will be correspondingly more complete foil immersion, and that will equalise the amount of work each surface contributes - until it finds itself in the steady state of constant heel, lots of lift and the hull lifted onto smaller waterplanes with a resultant reduction in hull drag.

 

The lift happening further to leeward than would have occurred in the WOXI setup allows more power to be extracted (it's a longer lever arm from Keel bulb to Foil, than from keel bulb to hull, in traditional canting keelers).

 

What could happen - is that if you think about flow in a 3D sense - if the boat is sailing with the foil fully submerged, as leeway increases the flow would vector ever so slightly from pure front to back - to a flow that will cross the foil from outboard to ever so slightly towards the centreline (irrespective of which tack you are on - this will increase the AOI of the second (outboard) surface) and decrease the AOI of the inboard surface - leading to negative feedback and course stability with respect to leeway. The boat just digs its shoulder down, accelerates and achieves betters VMG through increased boatspeed for the same amont of leeway.

 

The VPLP solution is different enough from original DSS to be seen as its natural evolution - it works in a more refined way to allow the boat to find its own sweet spot of heel, ride height and speed - this automatic feedback loop is important to IMOCA where the singlehanding has enough stress without having complex systems that require lots of constant adjustment.

 

This is the evolution (not revolution) of foil development that I alluded to when I berated you the other week - but you need to get your head around it better before you sound off like an expert (that you are not). You seem to have your head around AC72 setups - but this is different - and your posting shows your confusion.

 

Come on, your turn, flame away - I can do this till I run out of ink..... Hang on a minute; Cape Canaveral - I think you have a problem.....

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I wonder if there aren't three related foil systems. All having emerged post AC34:

1) TNZ style, with leeway coupled ride height correction. Tip stays wet (mostly). Perhaps only multi-million dollar AC boats can control these weapons.

2) Martin Fischer V foil variant. Tip stays dry (mostly). Ride height seems controlled (mainly) by less foil in the water. GC32 and FP sport these. An Everyman AC foil.

3) A Class J and Z four foil systems. Ride height perhaps akin to the Fischer concept - but in two parts rather than one.

 

And the new kid on the block: VPLP V foil stuck out to leeward on a monohull. Wow - mind officially blown!

 

Edit: But, for a monohull - the notion of ride height doesn't make much sense. Does the VPLP system even have rake control?

 

Although, I suppose immersing more lifting surface with more heel. And having less lift with less heel - might represesent a form of "auto-correction" all its own.

 

Think that the VPLP foil might look like a Fischer foil - set up to leeward - but the behavior quite a bit different...

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The fact that an "L" foil pointing outboard to leeward generates high and low pressure on the same side-and that it generates drag- is a proven fact*. The same thing will probably occur on the BP foil as it heels-perhaps they will sail at a specific angle of heel so this doesn't occur. Seems that tip portion is fairly small to generate all the lateral resistance for the boat compared to the area of previous Open 60 boards.


And there is a possibility that the BP foil, at the right angle of heel, could work with leeway coupling like the TNZ foil, though the outboard vertical tip seems short for that and for leeway resistance. And this foil is subject to the effects of angle of heel much more than are the UptiP foils on cats.


Innovative for sure but I'd like to know what Hugh Welbourn's opinion is vs a vs patent infringement or not.



*Ketterman proved this beyond a shadow of a doubt in a paper he wrote and by testing outward pointing foils on the Hobie trifoiler against a "normal" trifoiler-the one with outward pointing foils was slower. It was also the reason why he thought T-foils were inferior to inward pointing "L" foils.



post-30-0-62815300-1421781284_thumb.png

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From Pro Boat courtesy of VPLP-Verdier-same designers of the BP foil a proposed(but discarded) foil for Comanche:

post-30-0-68538100-1421790427_thumb.jpg

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When the boat is on stb tack, as it is shown in the picture, and heels more- the bottom portion of the foil will be more horizontal and vertical lift will increase a lot.

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When the boat is on stb tack, as it is shown in the picture, and heels more- the bottom portion of the foil will be more horizontal and vertical lift will increase a lot.

Thanks yes - I get it now. Pure lifting foil.

 

Edit: accidentally deleted previous post. Gotta remember Comanche has one m.

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They might end up with that thing back on. Some credit WOXI's light air performance to the steadying influence of the extra board.

 

Comanche got very sticky in the light - ostensibly because the rig would not steady in the chop.

 

But, again, given these monohull lifting boards only come into their own with velocity - not sure that makes sense!

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No foil works without velocity-it's the movement of the foil that creates lift.

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Floater, do you have any links about manual or electronic(automatic-hands off) rudder foil AOI adjustment on any new boat?

I just checked the AC 62 rule and all it says is that rudder rake can be changed 3 degrees(not plus or minus 3 degrees) but doesn't say how that is to be accomplished.

I doubt that it is a hands off electronic system-probably electro-hydraulic set by hand? I guess I would define "active" as hands off electronic or a wand. This would be manual like the rake control of the main foil, I think.

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Wrong thread!

Should'a looked a bit further down*...

 

This suggests that they are assuming electro/hydraulic - but there is nothing demanding that.

Wands are out

 

15. HYDRAULIC VALVES AND DRIVE CLUTCHES


15.1 Hydraulic valves and drive clutches for winch systems shall only be manually or electrically
operated.


15.2 Electrically operated valves and drive clutches shall be commercially available and
Competitors shall have had these approved by the Measurement Committee for use.


15.3 The system that controls electrically operated valves for appendage rotations about the rake
axis may only receive external manual input and positional input of the:
(a) appendage positions about the rake axis directly measured relatively to their own hulls;
(b] valves; and
(c] hydraulic rams,
that are used to control rake axis movement of appendages.


15.4 Other than permitted in Rule 15.3, hydraulic valves or drive clutches shall only be driven by
control signals (i.e. open and close) that depend on the following:
(a) the internal positional state of the valve being driven, such as the spool or cam position
relative to the valve body (but excluding signals that relate to the position, orientation or
motion of the valve in space);
(b] direct manual input; and
© an internally generated timing signal initiated by manual input.

15. Electrically operated valves and drive clutches:
(a) shall have the wiring for systems permitted in Rule 15.3 isolated and clearly identifiable
from the wiring systems permitted in Rule 15.4. The wiring for systems described in Rules
15.3 and 15.4 shall be isolated and clearly identifiable from any other wiring system. Each
of these systems shall have its own voltage supply which may be connected to a
common battery provided each system is electronically isolated; and
(b] shall be hard-wired and may use protocol-based communications (CAN, Ethernet, etc.)

*AC62rule ver 1.0 - there have been amendments since

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Thanks-very interesting! Seems like I read somewhere some time ago that hydrophobic coatings don't work to reduce drag on a boat hull. I could be wrong and this stuff would have to be a lot different than the coatings. Be interesting to test if a way could be found to bond that surface to a hull.

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Smoking gun:

 

(b] direct manual input; and

© an internally generated timing signal initiated by manual input.

 

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^ That's right - this was raised in the most recent thread about rules and autonomous control systems - and was completely ignored by those who claim 'nothing to see here'!?

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^ That's right - this was raised in the most recent thread about rules and autonomous control systems - and was completely ignored by those who claim 'nothing to see here'!?

True: Jack was silent. Which could mean there is more to learn, or nothing to learn.

 

Seems like a rather monumental chunk of foil control could be enabled by that little clause.

 

OTOH - perhaps it's not so important after all because pre-coded algorithms can only go so far when sailing variables like boat velocity and sea state vary greatly in actual sailing conditions.

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Sailors aboard the GC32 catamarans were hanging on for dear life all day as the high-tech speedsters were bouncing off waves and coming completely out of the water.

Skipper Flavio Marazzi led the Swiss entry Armin Strom Sailing to a one-point victory over ZouLou, the French entry skippered by Erik Maris.

Argo and Leenabarca were unable to compete in the last race after sustaining rudder damage in the rough conditions.

 

24293-2-1000.jpg

 

http://www.sailweb.co.uk/offshore/24293/quantum-key-west-race-week--crash-bang-wallop-finish

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Nice shots alright. Short snippets though - how did they perform overall?

 

and is there any consensus now on the right number of heads'ls for foiling boats? Two, one, zero? Does having a soft main vs wing change anything in this regard?

 

It looks like the AC45Fs might go for jib but no screecher - like the AC62s

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