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      Abbreviated rules   07/28/2017

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Tornado-Cat

The winning foils

3,407 posts in this topic

Boink. Rise above it mate.

 

These idiots, namely tornadoprat, SimonNerd, Doug Flawed, are all unqualified experts on this thread.

 

They are only here because nobody within the professional sailing industry wants them.

 

They spin bullshit, have no data to back up what they post, other than photos they copy from the WWW, and come here and make out they are world experts in hydro and aero dynamics!

 

It's there moment in the sun!

 

The AC thread is just a joke thanks to a few idiots that argue amongst themselves about stuff they do not understand.

 

SimonN has now left the thread due to humiliation! Just tornadocrap, and Dougflawed, left to go

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TC - "I guess you miss the fact that AC has rules which other foilers don't."

 

Did you two go to school together???? (That's Doug I am referring to......)

 

No I hadn't missed the fact, the rules or the realities.

 

The AC allows multiple sets of foils, each set of foils is designed to be optimum in a limited rage of conditions, and they can be changed between races as the teams see fit.

 

The point that all this makes is that current materials & technology cannot make a "one size fits all" type of solution to the problem.

Lift and Drag are intrinsically linked.

Their properties are directly to the cube of velocity.

 

We could also discuss how some profiles are twitchier than others. They may display favourable lift profile and apparently at lower perceived drag values - but they are so sensitive to attitude, that they can enter stall too easily - not properties that sail boats can currently exploit too heavily without having instantaneous active stabilisers (currently outlawed in AC) - but hell, why am I explaining this to the guy who was fooled into posting a faked foiling photo?

 

 

Thats not true. But it might require a rule change in the AC. The Q23, Whisper, Osprey, all use one foil for low and high speed.

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TC - "I guess you miss the fact that AC has rules which other foilers don't."

 

Did you two go to school together???? (That's Doug I am referring to......)

 

No I hadn't missed the fact, the rules or the realities.

 

The AC allows multiple sets of foils, each set of foils is designed to be optimum in a limited rage of conditions, and they can be changed between races as the teams see fit.

 

The point that all this makes is that current materials & technology cannot make a "one size fits all" type of solution to the problem.

Lift and Drag are intrinsically linked.

Their properties are directly to the cube of velocity.

 

We could also discuss how some profiles are twitchier than others. They may display favourable lift profile and apparently at lower perceived drag values - but they are so sensitive to attitude, that they can enter stall too easily - not properties that sail boats can currently exploit too heavily without having instantaneous active stabilisers (currently outlawed in AC) - but hell, why am I explaining this to the guy who was fooled into posting a faked foiling photo?

 

Thats not true. But it might require a rule change in the AC. The Q23, Whisper, Osprey, all use one foil for low and high speed.

What utter crap doug!

 

The technology is there to build anything they want! The designers have not figured out how to do it.....yet!

 

The aviation industry gave foils that cover a huge velocity range!

 

Anyway!... your suppositions are wrong!... you only think the design teams have not got solutions to these issues. They may not have issues VC as you suggest. You don't know!

 

I can tell you right now you are miles from what they can do.

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TC - I refer to your reference to Paragliders as single foil irrelevance.

Coming from the one who tells us that the rule specifies the "wing frame structure" I understand you can't see the relevance.

Now, do you want to keep entertaining us or STFU ?

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"Thats not true. But it might require a rule change in the AC."

Doug,

Doug,

Dougie Babe - we have already talked about your contradictory writings......

 

So which is it? "Not True"? OR "But it might require a rule change...."? Because the first is very definitive, but the second is very opposing.

 

Love the Red Ink - I feel all warm and cosy.....

 

Now.

 

TC - make me....... I thought this was a place to share. Shoot the breeze (along as its more than 4 knots.... and you can hydrofoil to your hearts content :P) etc. etc.

You seem upset.

Wanna share some of your thoughts? - they are so very insightful.....

 

 

 

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Firstly making any comparison of "sailing" between ACWS and the AC is a joke. ACWS is decided largely by gust management. The last AC was a drag race with a bit of match racing in relatively consistent breeze. There were some gains to be made by picking the tide and shifts but not much really compared to the lottery that is ACWS.

 

We should in bermuda see relatively consistent breeze and boat speed will matter. aero and cavitation will make a massive difference. Shape of foils, foil control, the thickness and cord of the foils etc will matter.

 

We may even see Australia 2 style foil covers in dock. I think we will see venting etc to manage cavitation.

 

Back to the rules question, whether or not the windward foil can be in the water is a big deal really, not for lift but for righting moment. The next generation of foiling cats will generate more righting moment through the windward foil and in turn increase the power you can generate through the wing and in turn be faster. It all going majorly pear shaped the moment the windward foil departs the water.

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Firstly making any comparison of "sailing" between ACWS and the AC is a joke. ACWS is decided largely by gust management. The last AC was a drag race with a bit of match racing in relatively consistent breeze. There were some gains to be made by picking the tide and shifts but not much really compared to the lottery that is ACWS.

 

We should in bermuda see relatively consistent breeze and boat speed will matter. aero and cavitation will make a massive difference. Shape of foils, foil control, the thickness and cord of the foils etc will matter.

 

We may even see Australia 2 style foil covers in dock. I think we will see venting etc to manage cavitation.

 

Back to the rules question, whether or not the windward foil can be in the water is a big deal really, not for lift but for righting moment. The next generation of foiling cats will generate more righting moment through the windward foil and in turn increase the power you can generate through the wing and in turn be faster. It all going majorly pear shaped the moment the windward foil departs the water.

Not accepted by the rule.

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TC - "I guess you miss the fact that AC has rules which other foilers don't."

 

Did you two go to school together???? (That's Doug I am referring to......)

 

No I hadn't missed the fact, the rules or the realities.

 

The AC allows multiple sets of foils, each set of foils is designed to be optimum in a limited rage of conditions, and they can be changed between races as the teams see fit.

 

The point that all this makes is that current materials & technology cannot make a "one size fits all" type of solution to the problem.

Lift and Drag are intrinsically linked.

Their properties are directly to the cube of velocity.

 

We could also discuss how some profiles are twitchier than others. They may display favourable lift profile and apparently at lower perceived drag values - but they are so sensitive to attitude, that they can enter stall too easily - not properties that sail boats can currently exploit too heavily without having instantaneous active stabilisers (currently outlawed in AC) - but hell, why am I explaining this to the guy who was fooled into posting a faked foiling photo?

 

 

Thats not true. But it might require a rule change in the AC. The Q23, Whisper, Osprey, all use one foil for low and high speed.

 

Doug

Stop and think. What you have posted here is total crap. The issue isn't whether a foil will work at both high and low speeds. Any foil being designed to work at all boatspeeds is a compromise, which is what Boink is talking about. Any boat that is only using a single foil design has a foil which is a compromise in some conditions. In that situation, it is the skill of the designer to come up with a foil that offers the best compromise when the expected conditions are taken into account. If it weren't for the rules, we would definitely have more than one set of foils for the A's, just like the Moths, who have now restricted themselves to 2 different foils per regatta.

 

You simply cannot have one single foil design which would be considered the optimum for all the conditions in which it sails. In the one design boats you mention, that is simply not an issue, because everybody has the same. In classes with more open rules, choosing which foils to use and when is a critical decision.

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Well said.

 

Of course, because it was written by Simon it will be rejected by floriDa's finest.

 

Doesn't mean its wrong however. Laws of physics will see to that.

 

I could see value in making the teams run contrasting coloured foils so that you could readily identify say Red foils as Set 1 and Blue as Set 2 to see more readily, what configuration they are running - much like Formula 1 now has coloured stripes on each different tyre variant.

 

It would at least stop non sailing commentators, or even, god forbid, Gary Jobson, from dribbling on endlessly with speculation about which set of foils they have chosen to use and whether it was changed from the previous race.

 

Note to TV producers here: if we are watching, we are clever enough to have hacked our way into a subscription tv service; we do not want to be treated as if we are a non sailing audience..... keep it technical and smart.

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We should in bermuda see relatively consistent breeze

Alas I've never sailed in Bermuda but from what I've read, it tends to the shifty and variable. Not Hudson shifty but not SF-consistent either. For that reason, I think those who think it's going to be all about boatspeed as AC34 was may be in for a surprise.

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TC - "I guess you miss the fact that AC has rules which other foilers don't."

 

Did you two go to school together???? (That's Doug I am referring to......)

 

No I hadn't missed the fact, the rules or the realities.

 

The AC allows multiple sets of foils, each set of foils is designed to be optimum in a limited rage of conditions, and they can be changed between races as the teams see fit.

 

The point that all this makes is that current materials & technology cannot make a "one size fits all" type of solution to the problem.

Lift and Drag are intrinsically linked.

Their properties are directly to the cube of velocity.

 

We could also discuss how some profiles are twitchier than others. They may display favourable lift profile and apparently at lower perceived drag values - but they are so sensitive to attitude, that they can enter stall too easily - not properties that sail boats can currently exploit too heavily without having instantaneous active stabilisers (currently outlawed in AC) - but hell, why am I explaining this to the guy who was fooled into posting a faked foiling photo?

 

 

Thats not true. But it might require a rule change in the AC. The Q23, Whisper, Osprey, all use one foil for low and high speed.

 

Doug

Stop and think. What you have posted here is total crap. The issue isn't whether a foil will work at both high and low speeds. Any foil being designed to work at all boatspeeds is a compromise, which is what Boink is talking about. Any boat that is only using a single foil design has a foil which is a compromise in some conditions. In that situation, it is the skill of the designer to come up with a foil that offers the best compromise when the expected conditions are taken into account. If it weren't for the rules, we would definitely have more than one set of foils for the A's, just like the Moths, who have now restricted themselves to 2 different foils per regatta.

 

You simply cannot have one single foil design which would be considered the optimum for all the conditions in which it sails. In the one design boats you mention, that is simply not an issue, because everybody has the same. In classes with more open rules, choosing which foils to use and when is a critical decision.

 

Simon, you're dead wrong. Foils that automatically change their CL can and have been developed. Wand based foils do that and in multihulls can be used to allow very early takeoff and, because of their dual independent wand systems, very high top end speeds since they automatically create more RM as required. UptiP and surface piercing foils can be designed with twist and more area that allows high lift for early takeoff and ditches the high lift portion of the foil as it rises above the water with speed.

With UptiP foils a foil designed for a specific narrow speed range might be faster in the specific conditions it was designed for but the "all round" foil would allow light air foiling(and high top end speed) in venues where the narrow range foil wouldn't work. There might have to be a rule change to mandate the use of all round foils in light air venues but they definitely could work.

And that would allow AC boats to foil in most conditions.

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It seems that some here think that teams work on different foil tips that they will be able to change between races. Can they demonstrate this possibility ?

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This article has a bunch on foils by Martin Fischer(Team France): https://translate.google.com/translate?depth=1&nv=1&rurl=translate.google.com&sl=auto&tl=en&u=http://www.voilesetvoiliers.com/course-regate/martin-fisher-une-choregraphie-du-vol-coupe-america/

 

Martin Fischer: " Each team has the right to use two sets of two foils for the races. But it is possible to divide the foil into two parts: in this case, it is allowed to build four upper parts and lower parts eight. To adapt to wind conditions. But we must solve the structural problem of a system of clips!"

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^ The Protocol (35.10) fixes the daggerboard limits.

 

- a maximum of 4 ACC daggerboards

plus

- a maximum of 6 non-ACC (turbo) daggerboards

 

But it also allows up to 30% of the mass (the entire 'horizontal' section?) of a ACC 'daggerboard' to be changed without it being counted as a new board - although any changes to a 'notified board' have to be announced to the MC. But the team can only do this a total of 4 times combined for their ACC boards.

 

Same < 30% change allowed for non-ACC boards, but up to 6 times combined total per team.

 

So that does not suggest race by race changes of 'clip-on tips' was ever contemplated.

 

......................................

 

Within the ACC Rule the Measurement Certificate includes which specific components were measured, including...

 

COMPONENTS

Port Daggerboard

Starboard Daggerboard

Port Rudder

Port Rudder Wing

Starboard Rudder

Starboard Rudder Wing

Wing

 

 

Multiple certificates are presumably allowed though, so.... 4 boards, including assymetrical arrangements, means how many certificates per boat...

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Agreed nav, it is a question of measurement.

 

AC Class rule 28.3 :

The measurement certificate ceases to be valid if there is any change to:

© the shape of the appendage surfaces

 

So, will they measure between each race or accept the first measurement certificates of the appendages ?

Or will it be left to the discretionary interpretation of the RD ?

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Read again. ^^

 

So that does not suggest race by race changes of 'clip-on tips' was ever contemplated.

 

 

You have to race your ACC boat 27 times minimum to win The AC - and that number assumes clean sweeps against your opposition in the both rounds of the playoffs and the Match - unlikely. So realistically you probably have to race 30-40 times - so something that is only allowed 4 times total (like changing tips) is not going to get you far (enough).

 

You would probably keep those 4, 'up to 30% change' allowances, in reserve for desperate shape changes and copying if you are getting thrashed - but that only if you haven't already used them up - between launch and the start of racing!

 

That's why I mentioned the mutiple measurement certificate option as the more likely way to go, in any attempt to better match foils to the prevailing conditions - giving you (in theory) the chance of switching board combinations from your pre-measured quiver.

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It was certainly contemplated by Martin Fischer! But he pointed out one of the big problems-how do you hold onto a tip with nearly the weight of the boat on it?

And, regardless, I think you could be right.......

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Martin F may have been differentiating between 'use two sets .. for the races' and 'build' 4 uppers and 8 lowers (for testing in different conditions).

 

It was a cool article either way.

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T-C Did you two go to school together???? (That's Doug I am referring to......)

Lift and Drag are intrinsically linked. Their properties are directly to the cube square of velocity.

 

 

Back to school Boink :)

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Good catch, TC! Thats funny.........

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Funny?!?
You 2 need to get out more.... Or, get a room.

'The wingsail consists of a common geometry main element and common structural design along with overall area limits,' Smyth explains.

Smyth believes there is a glaring omission in the current Cup over the limitation on daggerboards to just four that will be insufficient in the case of breakage.

He notes that teams are likely to build two sets of daggerboards – one optimised for light winds and more displacement sailing – which will be lower drag, and the second set-orientated around high winds, foiling, and speed.


Oh, does that not fall in line with your (self proclaimed) superior knowledge......?

 

Shame....

 

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Funny?!?

You 2 need to get out more.... Or, get a room.

 

'The wingsail consists of a common geometry main element and common structural design along with overall area limits,' Smyth explains.

 

Smyth believes there is a glaring omission in the current Cup over the limitation on daggerboards to just four that will be insufficient in the case of breakage.

 

He notes that teams are likely to build two sets of daggerboards – one optimised for light winds and more displacement sailing – which will be lower drag, and the second set-orientated around high winds, foiling, and speed.

 

Oh, does that not fall in line with your (self proclaimed) superior knowledge......?

 

Shame....

 

ah ah.. the more you post, the funnier :)

 

1) Who is the journo writing this BS ?

2) Are you talking about Scott Smyth, ACEA CFO. What does he know ? BTW do know the job of a CFO ?

 

And do you really believe they have 4 uppers and 8 tips in case they break ? :blink:

 

Go back to school Boink boink, first lesson, read the protocol, repeat after me.....

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More seriously now, team will have different foils, they will have certificates or will have to be measured between races. Do we have two races in the same day ? I guess yes.

Will the teams be able to have:

- time

- rule agreement

- technical possibility

 

to change the tip on the water between two races ?

 

If not, they will need foils with a larger specter of wind.

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Try Tim Smythe - he's only the head of Core Boat Builders, but what would he know?

 

You muppet. Whoops, we already been there......
Sorry Muppets - I like you and your show.

You moron.
Look him up - you will learn something.

You crap on as if you are the only person who knows anything, but when a real expert is quoted, you knock it back.
Classy.

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Oh great, another one who just comes here for the punch-up.

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Try Tim Smythe - he's only the head of Core Boat Builders, but what would he know?

 

You muppet. Whoops, we already been there......

Sorry Muppets - I like you and your show.

 

You moron.

Look him up - you will learn something.

 

You crap on as if you are the only person who knows anything, but when a real expert is quoted, you knock it back.

Classy.

^^ Calm down Boink.

 

You still did not attend the first lesson: "read the protocol"

Smythe is not the one deciding what is OD or not, the rules are.

The rules give a general shape of the sail but it is not OD.

He may very well construct identical wings for different teams too, it does not mean that the wing OD but that some team try to save money.

post-43482-0-96267600-1465226994_thumb.png

 

Second lesson, he may think that two sets of dagger boards is not enough in case they break but, again, he did not read properly the prot and other allowed possibilities.

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You still did not attend the first lesson: "read the protocol"

 

Or, as Tom Speer used to say: RTFP

 

Second lesson, he may think that two sets of dagger boards is not enough in case they break but, again, he did not read properly the prot and other allowed possibilities.

Don't understand: every team's allowed what, 6 Turbo boards - and they should be undistinguishable from AC50 boards, who's to say which is which?

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^ The MC will know which are which, they'll be identifiable and noted on the measurement certificates.

 

Not much point in setting limits if they are going to meaningfully control them - it's not IM in charge again is it?

 

 

(g) From December 8, 2015, a Competitor shall send the following

information to the Measurement Committee within seven (7) days of the

first installation of a Daggerboard in an AC Class Yacht or in a yacht

allowed for in Article 1.1(bbb)(ii). With reference to when the

Daggerboard was first included in the limits of Article 35.10 (a), such

declaration shall contain:

(i) the Daggerboard’s weight (Wo) recorded in kilograms;

(ii) an IGES file showing the shape of the Daggerboard; and

(iii) dated photographs of the daggerboard.

 

 

 

Not sure what the fuss is over breakages though - that is allowed for (though probably unrealistically) under the Protocol - over and above the 4 ACC board (+ 4 changes) limits.

 

 

If part of a Daggerboard is unintentionally damaged, as determined by

the Measurement Committee, it may be repaired to an identical shape

that has been approved as an IGES file for the Daggerboard. None of

the repair shall be constructed prior to the damage.

(f) If a Daggerboard referred to in Article 35.10 (a)(i) is unintentionally

damaged and unable to be repaired within an acceptable timeframe, a

Competitor may be allowed to use an existing Non-AC Class

Daggerboard for sailing and testing (but not racing) that has been

counted under that Competitor’s allocation in Article 35.10(a)(ii).

The Measurement Committee shall assess the damage and the

decision to allow the use of the Non-AC Class Daggerboard shall

require approval of both the Measurement Committee and the Regatta

Director
:o . The Measurement Committee and the Regatta Director may

set other limitations to this allowance.

 

 

Tim Gurr says they take six weeks to lay one up in carbon from an existing file - obviously too long to help a team in the middle of racing. And even though you could mill a heavier one from a block of material in a fraction of that time, the rules don't allow for either possibility - if you have already used your 4 'foil cards'.

 

So it's repair (and pray) - or make do with however many decent ones you have left! Not looking good for Artemis! :lol:

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Bien vu Xlot and nav, regarding the breakage.

post-43482-0-26283300-1465237318_thumb.png

 

Regarding the possibility to change the foil tips between races on the water, with IM (?) everything is possible ...

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nav,

"if you have already used your 4 'foil cards'."

 

 

IMO, they can use their 4 foils as much as they want as, going back to a "preset" does not constitute a modification. So they have enough tips to adapt to different conditions between 6 and 22 kts. Thus the question is mainly techical, will they be able to change it on the water.

A joker now, they can also change less than 10% of the total dagger board, not much but enough to modify the trailing edge ? I don't think it's enough but, who knows...

 

post-43482-0-95410000-1465257228_thumb.png

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Firstly making any comparison of "sailing" between ACWS and the AC is a joke. ACWS is decided largely by gust management. The last AC was a drag race with a bit of match racing in relatively consistent breeze. There were some gains to be made by picking the tide and shifts but not much really compared to the lottery that is ACWS.

 

We should in bermuda see relatively consistent breeze and boat speed will matter. aero and cavitation will make a massive difference. Shape of foils, foil control, the thickness and cord of the foils etc will matter.

 

We may even see Australia 2 style foil covers in dock. I think we will see venting etc to manage cavitation.

 

Back to the rules question, whether or not the windward foil can be in the water is a big deal really, not for lift but for righting moment. The next generation of foiling cats will generate more righting moment through the windward foil and in turn increase the power you can generate through the wing and in turn be faster. It all going majorly pear shaped the moment the windward foil departs the water.

Not accepted by the rule.

 

 

yes i know thats why i said next generation, not this generation.

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We should in bermuda see relatively consistent breeze

Alas I've never sailed in Bermuda but from what I've read, it tends to the shifty and variable. Not Hudson shifty but not SF-consistent either. For that reason, I think those who think it's going to be all about boatspeed as AC34 was may be in for a surprise.

 

 

video i have seen of bermuda look pretty consistent in the scheme of things. but hey i sail in the mountains on a lake so ...

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[…]

Back to the rules question, whether or not the windward foil can be in the water is a big deal really, not for lift but for righting moment. The next generation of foiling cats will generate more righting moment through the windward foil and in turn increase the power you can generate through the wing and in turn be faster. It all going majorly pear shaped the moment the windward foil departs the water.

 

So you're predicting manual control of lift (perhaps through AoA change of the main foil). Where will the power come from?

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nav,

"if you have already used your 4 'foil cards'."

 

 

IMO, they can use their 4 foils as much as they want as, going back to a "preset" does not constitute a modification. So they have enough tips to adapt to different conditions between 6 and 22 kts. Thus the question is mainly techical, will they be able to change it on the water.

A joker now, they can also change less than 10% of the total dagger board, not much but enough to modify the trailing edge ? I don't think it's enough but, who knows...

 

attachicon.gifnumber of dagger boards.PNG

 

 

 

You are getting muddled up I would say.....

 

You can't be seriously suggesting that when the rules allow only 4 foils and only 4 major modifications of those foils in total - that you could modify a board, use it in a race, return it to it's original spec and say it does not count as an extra board?? :lol:

 

Still that is a very sloppily written clause, I am pretty confident it goes with the preceding clause and was supposed to mean; if you screwed up your mods and overstepped the max percentages allowed, you could back up without penatly - IF YOU DIDN'T USE IT!

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I've smoked dope, chewed rope, danced, French romanced, fucked, farted, fought, shot the moon and drove big trucks. I've been to Janesville, Maine, Spain, Spokane, and Fort Wayne, seen three world fairs, been around the world twice, looked danger in the face, and seen goats fuck in the marketplace, but I ain't never seen no shit like the shit that happens on this thread.

 

If you bunch of muppets could actually agree on one of your bullshit theories would actually give some credibility to this mindless crap!

 

This describes you lot perfectly.... but it may fly over your head....

 

Petronius Arbiter (died 66 a.d.)

We trained hard . . . but it seemed that every time we were beginning to form up into teams we would be reorganized. I was to learn later in life that we tend to meet any new situation by reorganizing: and a wonderful method it can be for creating the illusion of progress while producing confusion, inefficiency, and demoralization.

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Along with smoking dope and your other adventures you owe your audience the time needed to correctly attribute words you did not author. The satirical insight to reorganization is taken from Harper's Magazine, 1957. The article was written by Charlton Ogburn. He submitted the article thinking it might qualify for publication. His work was so well received he left government service, likely the source of his thoughts on reorganization, for a career in writing. Ogburn foresaw a consequence of America's financial support to the French as the colonies in French Indochina collapsed from corruption and cronyism, much of it predicated on French officials encouraging citizens converting to Christianity. We know the consequence Ogburn wrote against to be the Viet Nam War.

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Plonker!... i did not author them! That why I referenced the authors name in the post.

 

But you should check your facts! 66 ad is a little bit earlier than it Ogburn!

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nav,

"if you have already used your 4 'foil cards'."

 

 

IMO, they can use their 4 foils as much as they want as, going back to a "preset" does not constitute a modification. So they have enough tips to adapt to different conditions between 6 and 22 kts. Thus the question is mainly techical, will they be able to change it on the water.

A joker now, they can also change less than 10% of the total dagger board, not much but enough to modify the trailing edge ? I don't think it's enough but, who knows...

 

attachicon.gifnumber of dagger boards.PNG

 

 

 

You are getting muddled up I would say.....

 

You can't be seriously suggesting that when the rules allow only 4 foils and only 4 major modifications of those foils in total - that you could modify a board, use it in a race, return it to it's original spec and say it does not count as an extra board?? :lol:

 

Still that is a very sloppily written clause, I am pretty confident it goes with the preceding clause and was supposed to mean; if you screwed up your mods and overstepped the max percentages allowed, you could back up without penatly - IF YOU DIDN'T USE IT!

 

Question of interpretation of the rule. They allow 4 mofications but if the foil goes back to a previous allowed shape it is not considered a modication. That implies to change the tip with another already measured and respecting the 70% rule.

Martin Fisher said they were working on solutions with clips that had to be strong enough to support the weight of the boat...

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^ No.

Martin Fisher works on 2 sets of foils and 4 sets of tips attached with clips, and it is a structurally difficult to solve the equation.

 

Voilesetvoiliers.com : Mais les équipes ont le droit de changer de foils !

M. F. : Chaque team a le droit d’utiliser deux jeux de deux foils pour les courses. Mais il est possible de scinder le foil en deux parties : dans ce cas, il est autorisé de construire quatre parties hautes et huit parties basses. Pour s’adapter aux conditions de vent. Mais il faut résoudre le problème structurel par un système de clips !

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And your point is?

 

He is allowed to mess about with up to 6 foils* for surrogate boats (and change 30% of them by mass up to 6 times in total) - so do those ^ numbers prove anything about how the 4 ACC boards will be utilised?

 

* as many as he likes actually - if they are never 'installed'.

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[…]

Back to the rules question, whether or not the windward foil can be in the water is a big deal really, not for lift but for righting moment. The next generation of foiling cats will generate more righting moment through the windward foil and in turn increase the power you can generate through the wing and in turn be faster. It all going majorly pear shaped the moment the windward foil departs the water.

 

So you're predicting manual control of lift (perhaps through AoA change of the main foil). Where will the power come from?

 

 

 

thats what they do anyway, control the AOA of the main foil, now its also complimented with rudder rake control. thats what the hydraulic grinders do, power the controls. but as i said the windward foil is not allowed to to add to righting moment under this rule. but in the future that will be part of it. making for more powered up and faster boats. in time.

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They would have to make a lot of changes. The UptiP foils work with leeway-if a second foil was dropped in the foil would have to be redesigned.

There have been a three trimarans(and a couple of early cats) using downforce from the windward foil and now a couple of small cats-what these boats all have in common besides using the windward foil for downforce are wand controlled main T-foils with flaps (or "feelers" on the Hobie Trifoiler that move the whole foil). The wand /feeler system makes lift and righting moment automatic. The largest wand controlled main foils I know of were on Dr. Sam Bradfields 40' SKAT.

There are problems but I'd bet it could work on a 50' cat foiler.......

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Pretty clear that they are going to use 2 sets of upper foils and 4 sets of tips that they will change between races.

 

More interesting is that from Martin Fisher:

 

M. F. : Le profil est différentiel le long du «tip», justement parce que cette partie vrille, comme une aile. C’est comme une voile qui ouvre dans les hauts : ces formes sont très complexes. Les «shafts» ont leur propre profil puisqu’ils ont un double rôle : antidérive particulièrement au près et porte «tip». Il y a donc plusieurs possibilités de formes de foils selon les conditions de vent, en jouant sur les profils, sur les épaisseurs, sur le vrillage.

 

The profile of the shaft will change depending of the load and they will play both the role of tip support and dagger board.

 

So we can guess that their upper foils will be different, with different thickness and twist.

 

Now let's think of what they are trying to guess:

- what is the best upper foil depending of the wind

- what are the different possible tips. We can see some rounded tips, is it for better stability while having more RM or be able to foil higher upwind without drifting ?

- what are the best tips depending on the conditions of wind

- what is the best combination ?

- should be have some versatile foils for different conditions of wind ?

- what is the best clip ?

- how do we change tips during racing ?

 

Teams trying that now take a huge advance.

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[…]

Back to the rules question, whether or not the windward foil can be in the water is a big deal really, not for lift but for righting moment. The next generation of foiling cats will generate more righting moment through the windward foil and in turn increase the power you can generate through the wing and in turn be faster. It all going majorly pear shaped the moment the windward foil departs the water.

 

So you're predicting manual control of lift (perhaps through AoA change of the main foil). Where will the power come from?

 

 

 

thats what they do anyway, control the AOA of the main foil, now its also complimented with rudder rake control. thats what the hydraulic grinders do, power the controls. but as i said the windward foil is not allowed to to add to righting moment under this rule. but in the future that will be part of it. making for more powered up and faster boats. in time.

 

 

And we've also seen the result when there's not enough power to make adjustments. These boats are designed and built by very clever people, so I don't put it past them to work it out if need be, but continuous manual hydraulic control of AoA of both foils without some form of stored energy is going to need a lot of clever thinking.

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It's already been done with dual, independent wand controlled main foils. They automatically provide lift and RM as required........

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Pretty clear that they are going to use 2 sets of upper foils and 4 sets of tips that they will change between races.

 

More interesting is that from Martin Fisher:

 

M. F. : Le profil est différentiel le long du «tip», justement parce que cette partie vrille, comme une aile. C’est comme une voile qui ouvre dans les hauts : ces formes sont très complexes. Les «shafts» ont leur propre profil puisqu’ils ont un double rôle : antidérive particulièrement au près et porte «tip». Il y a donc plusieurs possibilités de formes de foils selon les conditions de vent, en jouant sur les profils, sur les épaisseurs, sur le vrillage.

 

The profile of the shaft will change depending of the load and they will play both the role of tip support and dagger board.

 

So we can guess that their upper foils will be different, with different thickness and twist.

 

Now let's think of what they are trying to guess:

- what is the best upper foil depending of the wind

- what are the different possible tips. We can see some rounded tips, is it for better stability while having more RM or be able to foil higher upwind without drifting ?

- what are the best tips depending on the conditions of wind

- what is the best combination ?

- should be have some versatile foils for different conditions of wind ?

- what is the best clip ?

- how do we change tips during racing ?

 

Teams trying that now take a huge advance.

 

To the extent that its legal I'll bet this is a major focus of foil R & D. The Teams that come up with a good system will be quite advanced. The "clips" are an interesting problem-can't wait to see the solutions......

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^ I'd love to hear how you think that ^ sort of set up gets by the measurers - please read the "Limits on Daggerboards" section of the Protocol and the "Daggerboards" section of the ACC rule before answereing

 

and also when did it became...

 

- "Pretty clear that they are going to use 2 sets of upper foils and 4 sets of tips that they will change between races." ?

 

- and whom exactly will be doing this?

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please read the "Limits on Daggerboards" section of the Protocol and the "Daggerboards" section of the ACC rule before answereing

 

I did, the prot is clear as mud, and I am no definitive answer, just one interpretation.

I tried to chose what, I think, is relevant:

 

Declaration of the dagger boards:

post-43482-0-38081400-1465616335_thumb.png

 

Number of boards

 

post-43482-0-38619400-1465616369_thumb.png

 

What is not considered a modification

post-43482-0-64669900-1465616406_thumb.png

 

That let me think that they can change tip already measured between races, I might be wrong though.

 

That said, I how they won't be able or allowed to do so between 2 races on the water, I would prefer to see them with more versatile foils.

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^

- what do you mean by 'tip'

- roughly what % of the total foil weight do you think this tip constitutes?

- do you think the third clause you quote 35.10 d (v) allows a foil to be used in a race in it's modified form - before it's reverted to it's notified form

- what leads you to think 'changing tips' will be used during ACC races

- who do you think will be doing this

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^

- what do you mean by 'tip'

The lifting part of the foil, some already use that word

 

- roughly what % of the total foil weight do you think this tip constitutes?

I would say less than 30% but if some have real figures it would be interesting to know

 

- do you think the third clause you quote 35.10 d (v) allows a foil to be used in a race in it's modified form - before it's reverted to it's notified form

Because competititors do not need to satisfy article g an h, as it is not considered a modification

 

- what leads you to think 'changing tips' will be used during ACC races

The word used by Martin Fisher "clip" which is a way change configuration quickly

Also, lift and drag are increasing at the square of the speed, so they need large tips for light wind and smaller ones for the high end.

 

- who do you think will be doing this

If Marting Fisher is right, TF might be working on it. However we have not seen that happen on the water, as far as I know.. My personal guess is that scooped tips could be tried to avoid resorting to that, just a guess though

Again, I am just trying to interpret the Prot and will be happy to be proven the contrary

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This article has a bunch on foils by Martin Fischer(Team France): https://translate.google.com/translate?depth=1&nv=1&rurl=translate.google.com&sl=auto&tl=en&u=http://www.voilesetvoiliers.com/course-regate/martin-fisher-une-choregraphie-du-vol-coupe-america/

 

Martin Fischer: " Each team has the right to use two sets of two foils for the races. But it is possible to divide the foil into two parts: in this case, it is allowed to build four upper parts and lower parts eight. To adapt to wind conditions. But we must solve the structural problem of a system of clips!"

So, Nav: is Fischer wrong?

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^ Thanks for the quote, do you know for sure if he was referring to ACC or non-ACC (Turbo) boats?

 

 

If the tips he's talking about are over 10% of the weight* of the total foil and if he is suggesting you can do this more than 4 times total (for the AC class) - then he's wrong as far as I can see and as I've stated above, with quotes....

* and this probably applies no matter what % of the total weight they are.

 

 

 

(i) Competitors may modify their AC-Class Daggerboards a

combined maximum of four (4) times provided at least 70% of the

Daggerboard, determined by weight, maintains its original shape

and structure.

 

 

 

 

But 4 or fewer changes would be fine - but what would it achieve in the big picture??

 

 

So that does not suggest race by race changes of 'clip-on tips' was ever contemplated.

 

 

You have to race your ACC boat 27 times minimum to win The AC - and that number assumes clean sweeps against your opposition in the both rounds of the playoffs and the Match - unlikely. So realistically you probably have to race 30-40 times - so something that is only allowed 4 times total (like changing tips) is not going to get you far (enough).

 

You would probably keep those 4, 'up to 30% change' allowances, in reserve for desperate shape changes and copying if you are getting thrashed - but that only if you haven't already used them up - between launch and the start of racing!

 

That's why I mentioned the mutiple measurement certificate option as the more likely way to go, in any attempt to better match foils to the prevailing conditions - giving you (in theory) the chance of switching board combinations from your pre-measured quiver.

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^ Thanks for the quote, do you know for sure if he was referring to ACC or non-ACC (Turbo) boats?

 

 

If the tips he's talking about are over 10% of the weight* of the total foil and if he is suggesting you can do this more than 4 times total (for the AC class) - then he's wrong as far as I can see and as I've stated above, with quotes....

* and this probably applies no matter what % of the total weight they are.

 

 

 

(i) Competitors may modify their AC-Class Daggerboards a

 

combined maximum of four (4) times provided at least 70% of the

 

Daggerboard, determined by weight, maintains its original shape

 

and structure.

 

 

 

 

 

nav, they can modify it max 4 times, but if they come back to a specification already notified, it is not considered to be a modification. (v)

 

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^ This is tiresome.

 

I asked how much of the foil your imaginary tips are. You said 'less than 30%', but then insist that a clause that allows a maximum change of 10% would apply.

 

And surely you can see the lack of logic (and the lack of 'cost savings') if having specified a maximum of 4 foils*, you then allow unlimited changes!? :wacko:

 

 

* with limited allowance for modification and repairs

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nav, I agree on the lack of logic but I don't see what you see, perhaps I am missing something.

Article 35.d.v is not linked to iii et iv in the version of the protocol I read

Where do you see that v is linked to the 10% ? I see two different topics, perhaps I am wrong but...

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^

 

Take a notified foil, modify it (by more than 10% - or change the tip), install it (so race or train with it).....

 

Any AC Class Daggerboard shall be included in the limits of Protocol

Article 35.10(a)(i) when it is first installed on an AC Class Yacht and

such yacht is afloat with it installed.

 

 

 

and it counts - for sure, what you do to it after that is irrelevant.

 

 

 

This could not logically apply to an 'installed' foil....it would contradict that ^ clause

 

(v) When a Competitor reverts a Daggerboard to a specification

previously notified by that Competitor under articles 35.10 (g) and

(h) it shall not constitute a modification.

 

 

"Scassani, clean up on aisle 9"

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This is what I read:

 

1) teams may have 4 foils maximum when installed = 2 sets of boards, either light wind and stronger wind or a spare one

2) they are allowed 4 mofidifications maximum

3) however reverting to a previous accepted specification is not a modification

 

The question is to know if the 3) is appliable between races. If yes, I think that allows to change the tips, or the whole foil. Anyway, w'll see how they read the rule or ask for interpretation.

I think OR has been measured something like 27 times at the last AC

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This is what I read:

 

1) teams may have 4 foils maximum when installed = 2 sets of boards, either light wind and stronger wind or a spare one

 

You can have as many foils as you want - you can only ever install 4. Nor do they have to be 'sets'

 

2) they are allowed 4 mofidifications maximum

 

well done

 

3) however reverting to a previous accepted specification is not a modification

 

so you haven't broken the modification limit (2^) by simply working on a board but then reverting it to it's notified condition - but you will break the daggerboard limit (1^) if you install one of these boards in it's modified condition!

 

The question is to know if the 3) is appliable between races. If yes, I think that allows to change the tips, or the whole foil. Anyway, w'll see how they read the rule or ask for interpretation.

I think OR has been measured something like 27 times at the last AC

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This is what I read:

 

1) teams may have 4 foils maximum when installed = 2 sets of boards, either light wind and stronger wind or a spare one

 

You can have as many foils as you want - you can only ever install 4. Nor do they have to be 'sets'

OK

 

2) they are allowed 4 mofidifications maximum

 

well done

OK

 

3) however reverting to a previous accepted specification is not a modification

 

so you haven't broken the modification limit (2^) by simply working on a board but then reverting it to it's notified condition - but you will break the daggerboard limit (1^) if you install one of these boards in it's modified condition!

 

Here is the interpretation.

 

IMO, even installed dagger boards may be modified:

- (b ) any dagger board shall be included in the limit of 35.10 a.i

Now, 35.10 a.i may be modified:

- d) Dagger boards referred in article 35.10.a.i may be modified as follows:

 

Furthermore:

(v) refers to (g) which details the condtions on how a competitor shalle send the info to the measurement committee.

 

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even installed dagger boards may be modified:

 

 

Is that even in question?

 

Of course you can modify any of your up to 4 'notified' boards, modify one multiple times if you like - but not more than 30 %, make sure you tell the MC, don't change the weight by more than 10%, don't do more than 4 of these modifications in total etc etc.

You can do unlimited minor modifications, < 10%.

You can even do additional repairs to damaged boards - if you ask first.

 

 

But: Any board that is 'modified', i.e. is recognised as a different board - from it's original notified form, will count as an extra board, the first time it's installed. (and thus count against both Daggerboard limits and modification limits)

 

(regardless what shape it might take in some later iteration)

 

 

maybe... we are subject to ACDUH's imperfect rule writers afterall

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even installed dagger boards may be modified:

 

 

Is that even in question?

 

Of course you can modify any of your up to 4 'notified' boards, modify one multiple times if you like - but not more than 30 %, make sure you tell the MC, don't change the weight by more than 10%, don't do more than 4 of these modifications in total etc etc.

You can do unlimited minor modifications, < 10%.

You can even do additional repairs to damaged boards - if you ask first.

 

 

But: Any board that is 'modified', i.e. is recognised as a different board - from it's original notified form, will count as an extra board, the first time it's installed. (and thus count against both Daggerboard limits and modification limits)

 

(regardless what shape it might take in some later iteration)

 

 

maybe... we are subject to ACDUH's imperfect rule writers afterall

OK, we are very close now.

(v) considers that reverting to a previous specification does not constitute a new modification.

So my point is that they could keep the already measured tips and choose the one they want depending of the wind conditions without being considered as modifying the foil.

Not sure it is useful though as they could change the whole foil though, but Martin Fisher is considering it. And why would he be considering it for the T which does not have the same limitations ?

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I still think that MF was making a distinction between modifying foils that are built and installed on the T's for testing, versus the ones for installation on the ACC boat. Perhaps it gets lost in the translation?

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I never read G trans. This is the original but cannot exclude a mistake from the magazine or intox:

 

Voilesetvoiliers.com : Mais les équipes ont le droit de changer de foils !
M. F.
: Chaque team a le droit d’utiliser deux jeux de deux foils pour les courses. Mais il est possible de scinder le foil en deux parties : dans ce cas, il est autorisé de construire quatre parties hautes et huit parties basses. Pour s’adapter aux conditions de vent. Mais il faut résoudre le problème structurel par un système de clips !

 

Are teams allowed to change foils ?

M.F: Each team has to right to use two sets of 2 foils for races. But it is possible to separate the foils in two pieces: in this case it is allowed to build 4 high parts parts and 8 low parts. Allowing to adapt to different wind conditions. However we have to solve the structural problem with clips !

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'Use' in the first part, 'build' in the second part.

 

Maybe you could email him and ask him to clarify?

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^

- what do you mean by 'tip'

The lifting part of the foil, some already use that word

 

- roughly what % of the total foil weight do you think this tip constitutes?

I would say less than 30% but if some have real figures it would be interesting to know

Again, I am just trying to interpret the Prot and will be happy to be proven the contrary

 

 

The theoretical static loading on the main foils is about 90% of the all up weight of the boat .. the other 10% is supported by the rudder foils .. I say theoretical because it is impossible to have a static loading on the foils when sailing.

 

In practice the loads will always be dynamic and will depend on how fast the boat is travelling and how big the waves are. The dynamic loading in rough conditions could be 2 o 3 times the theoretical static loading and on top of that an additional allowance needs to be made of at least 1.5 times the calculated loading to make sure that they don't fail as Oracle's did when they launched their AC72.

 

In addition there is a fatigue factor which relates to the stress fluctuations that will occur during the sailing life of the foils .. this may be highly significant if they use metal connections to enable changes to the configuration to be made.

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Terry

I think you are somewhat low on your loads. You aren't taking into account loads due to the lateral resistance the foils also produce. Even on flat water, depending on what point of sailing you are on, you are probably looking at loads 2-3 times what you are calling "theoretical static loads" and that increases significantly with shock loads due to waves, gusts, falling off foils etc. My understanding is that last time around, everybody significantly under estimated the loads on the main foils. In some cases, it led to complete failure (anybody seen a bit of foil bob out the back of a boat ;) ) while in others, it just saw significant flex which made steady flight more difficult to achieve.

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Terry

I think you are somewhat low on your loads. You aren't taking into account loads due to the lateral resistance the foils also produce. Even on flat water, depending on what point of sailing you are on, you are probably looking at loads 2-3 times what you are calling "theoretical static loads" and that increases significantly with shock loads due to waves, gusts, falling off foils etc. My understanding is that last time around, everybody significantly under estimated the loads on the main foils. In some cases, it led to complete failure (anybody seen a bit of foil bob out the back of a boat ;) ) while in others, it just saw significant flex which made steady flight more difficult to achieve.

 

Read what I wrote again .. slowly this time.

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'Use' in the first part, 'build' in the second part.

 

Maybe you could email him and ask him to clarify?

^ I don't think we will get an official clarification.

However if we read the prot what he says makes sense:

 

- Each team is authorized to make 4 modifications that can be declared as AC foils

- Each team is allowed 4 foils

- Each team can change 30% of the foil without being considered a modification if it is going back to a previous specification

 

So each team can dispose of 4 upper parts and 8 lower parts (if previously declared).

 

Difficult to explain, I don't know if it is a loop hole, but it is the litteral interpretation of the protocol.

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^ So I think you are misinterpreting things

 

You seem convinced you can modify a board, use it and later revert it to original spec - and no one will notice, care, or count it against your max 4 different board allowance - completely illogical IMO

 

But leaving that aside for a moment...

 

- please explain how is it possible to 'modify' 4 tips into 8? Is MF a magician? And if 4 can become 8, why not 50..or 100 - given that the number 8 is missing from the Protocol all together.

 

Are you just making this up?

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edit

 

^ Getting tiresome:

 

i) Competitors may modify their AC-Class Daggerboards a

combined maximum of four (4) times provided at least 70% of the

Daggerboard, determined by weight, maintains its original shape

and structure.

 

4 x 2 = 8

 

For the rest:

 

(v) When a Competitor reverts a Daggerboard to a specification

previously notified by that Competitor under articles 35.10 (g) and

(h) it shall not constitute a modification.

 

I did not write the rules, I read it and it seems that Martin Fischer gets to the same conclusion. I don't say it was intended in the rule though !

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Terry

I think you are somewhat low on your loads. You aren't taking into account loads due to the lateral resistance the foils also produce. Even on flat water, depending on what point of sailing you are on, you are probably looking at loads 2-3 times what you are calling "theoretical static loads" and that increases significantly with shock loads due to waves, gusts, falling off foils etc. My understanding is that last time around, everybody significantly under estimated the loads on the main foils. In some cases, it led to complete failure (anybody seen a bit of foil bob out the back of a boat ;) ) while in others, it just saw significant flex which made steady flight more difficult to achieve.

 

Read what I wrote again .. slowly this time.

he can't read and his statement a absolute crap. H

Simon just guess's stuff based on assumptions that have no scientific or tested basis.

 

Simon's sources and resources base are in his head. I can tell you categorically that the teams did not under estimate the loadings. But they did learn a lot more about foil shape and it affect on the loading ( twist, bend etc...). They also looked at the asymmetrical and symmetrical pros and cons with regard to loading v lift v drag.

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edit

 

^ Getting tiresome:

 

i) Competitors may modify their AC-Class Daggerboards a

 

combined maximum of four (4) times provided at least 70% of the

 

Daggerboard, determined by weight, maintains its original shape

 

and structure.

 

4 x 2 = 8

 

For the rest:

 

(v) When a Competitor reverts a Daggerboard to a specification

 

previously notified by that Competitor under articles 35.10 (g) and

 

(h) it shall not constitute a modification.

 

I did not write the rules, I read it and it seems that Martin Fischer gets to the same conclusion. I don't say it was intended in the rule though !

 

Again please....

 

4? 2? 8?

 

Didn't you suggest each team could end up with 8 horizontal elements all available at once and switch them at will - via a clip on system? Is that somehow confirmed by you equation?

 

And why keep prattling on about the modification limit while completely ignoring the board limit? Each new board installed, or changed and then re-installed, counts - 4 max, after that you're cheating. Simple!

 

Even if you could modify all the boards you want and *abracadabra* make 2 from one as you seem to think - you can't use them, because you've already used all 4 foil cards

 

You didn't write the rule, nor are you reading all of it.

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Ok, I'll repeat

 

1) read my previous posts: 4 allowed modifications x 2 = 8 tips

 

2) We always agreed on the 4 boards limit. You think that, then, it is finished, they used all their cards. I say that article 35.10.d still applies and allows new mofications. Article (v) is even more specific as it applies to boards already measured. Now, how does your interpretation work if (v) applies to already measured boards ?

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The "front page" has suggested that the mainfoil in this picture is bending, not canted. But what would the force be to push the foil to this angle? The force caused by lateral resistance would push the vertical portion of the foil the other way.

If its canted I can see where that would be done to move the center of vertical lift further outboard to increase the righting arm(and RM). But I can't see it bent to this angle.


no8w7q.jpg

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I've smoked dope, chewed rope, danced, French romanced, fucked, farted, fought, shot the moon and drove big trucks. I've been to Janesville, Maine, Spain, Spokane, and Fort Wayne, seen three world fairs, been around the world twice, looked danger in the face, and seen goats fuck in the marketplace, but I ain't never seen no shit like the shit that happens on this thread.

 

If you bunch of muppets could actually agree on one of your bullshit theories would actually give some credibility to this mindless crap!

 

This describes you lot perfectly.... but it may fly over your head....

 

Petronius Arbiter (died 66 a.d.)

We trained hard . . . but it seemed that every time we were beginning to form up into teams we would be reorganized. I was to learn later in life that we tend to meet any new situation by reorganizing: and a wonderful method it can be for creating the illusion of progress while producing confusion, inefficiency, and demoralization.

A fine post, except its pronounced "Spoke-ann".

 

Carry on.

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^^ Not the first time this foil has been seen - or commented on. It curves outboard, presumably to widen the footprint to maximise RM

 

13446389_10206980844059088_509255037_o1.

 

But what's in the wing?

 

Note also in that FP piece as it relates to the rule discussion in this thread: With variable ride control (à la the Moth) and changing foil shapes banned, designers tell us that variable foil bend characteristics may prove the key to the top speed puzzle.

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Do you know in what thread this foil was previously mentioned? As to "changing foil shapes" it seems we already know that boards can be modified without regard to section or planform so what the FP was referring to: changing foil shapes banned, - doesn't seem to make sense.

---

That's a weird shape in the wing.I think I remember seeing something like it in one of the AC 72's but no idea what it could be.

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Re 'variable foil bend characteristics'

 

Isn't there a para in the design rule somewhere, that proscribes limits on allowable foil deflections under load?

 

Been months since I read it, could be mis-remembering.

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Doug the rules seems somewhat contradictory as to what changes can be made to foils (and more importantly if they can then be used). It seems one designer has suggested one thing but if the FP is to be believed another group think the opposite.

 

So where do you get this from? ..... we already know that boards can be modified without regard.....

 

There have been no requests for an interpretation of this aspect of the rules that I know of, but then again while there is a process for getting interpretations - it does not appear to cover the Protocol in which the foil limits are contained!?

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Doug the rules seems somewhat contradictory as to what changes can be made to foils (and more importantly if they can then be used). It seems one designer has suggested one thing but if the FP is to be believed another group think the opposite.

 

So where do you get this from? ..... we already know that boards can be modified without regard.....

 

There have been no requests for an interpretation of this aspect of the rules that I know of, but then again while there is a process for getting interpretations - it does not appear to cover the Protocol in which the foil limits are contained!?

 

From your post 257 and what Martin said-true for at least 30% of the board-and maybe more-I'm not 100% sure. No mention anywhere, that I've seen, that refers specifically to any limit on the planform of the foil or the foil section except "maintains its original shape...." speaking of 70% of the board.

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Do you know in what thread this foil was previously mentioned? As to "changing foil shapes" it seems we already know that boards can be modified without regard to section or planform so what the FP was referring to: changing foil shapes banned, - doesn't seem to make sense.

---

That's a weird shape in the wing.I think I remember seeing something like it in one of the AC 72's but no idea what it could be.

 

It looks to me like a removable panel with something behind it. Perhaps something that will eventually be smaller, or something temporary for testing replacing a component that would normally be smaller.

Random google brings up this which kind of supports that theory.

https://www.google.co.nz/search?q=Oracle+AC50&client=firefox-b-ab&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiu3rmk9rfNAhWEkpQKHUjgCGsQ_AUICCgB&biw=1920&bih=875

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This is what I saw on an AC 72-doesn't look exactly like the thing on the 45 wing but something was surely there-maybe just access to the wing mechanics?

photo by Grenier

 

2r7wn5x.jpg

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Regarding the foil changes, IMO, it concerns the 70% that should not be modified. But what is the 30%, the tip ? or the upper part ? well, it is not specified :)

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I wasn't pointing out the zipper in the wing, Oracle has had those on all their boats for at least 1½ AC cycles - it was the bulge behind it that was mildly interesting, as opposed to the previously and openly displayed outwardly curved foil.

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A different location - possibly similar purpose, who could know beyond a w.a.g.

 

13446389_10206980844059088_509255037_o1.

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I've got pictures of that all opened up on OR. Let me check my files and I'll post if found.

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^^ Not the first time this foil has been seen - or commented on. It curves outboard, presumably to widen the footprint to maximise RM

 

13446389_10206980844059088_509255037_o1.

 

But what's in the wing?

 

Note also in that FP piece as it relates to the rule discussion in this thread: With variable ride control (à la the Moth) and changing foil shapes banned, designers tell us that variable foil bend characteristics may prove the key to the top speed puzzle.

Bloody hell, they've reversed one foil to outfacing? Tricky. But all the eggspurts know that won't work. The silly dingbats?

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^^ Not the first time this foil has been seen - or commented on. It curves outboard, presumably to widen the footprint to maximise RM

 

13446389_10206980844059088_509255037_o1.

 

But what's in the wing?

 

Note also in that FP piece as it relates to the rule discussion in this thread: With variable ride control (à la the Moth) and changing foil shapes banned, designers tell us that variable foil bend characteristics may prove the key to the top speed puzzle.

Bloody hell, they've reversed one foil to outfacing? Tricky. But all the eggspurts know that won't work. The silly dingbats?

 

Been watching Ben Hur to much...

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^^ Not the first time this foil has been seen - or commented on. It curves outboard, presumably to widen the footprint to maximise RM

 

13446389_10206980844059088_509255037_o1.

 

But what's in the wing?

 

Note also in that FP piece as it relates to the rule discussion in this thread: With variable ride control (à la the Moth) and changing foil shapes banned, designers tell us that variable foil bend characteristics may prove the key to the top speed puzzle.

 

Bloody hell, they've reversed one foil to outfacing? Tricky. But all the eggspurts know that won't work. The silly dingbats?
yip! Simon, doug, and nav will be all over this like a scrotum rash!

 

No doubt Russell will be seeking their business and they will be on the boat tomorrow advising on trim detail!

 

Come in Simon!... we need your expertise... after all sailing A classes with your mates makes you.... the man!

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Sorry to be a bit later, regarding the drag debate: proportional to Velocity squared or cubed ?

 

According to Mark Drela excellent book "Flight Vehicule Aerodynamics" ISBN 978-0-262-52644-9

 

In Chapter 4 / 4.11.4

Regarding the dissipation coefficient (which is close to drag concepts) it is mentionned:

 

The weak dependence of Cd (Dissipation coef) on pressure gradients (assuming fixed transition locations) indicates that the dissipation D(s)= Rho*Ue^3*Cd

 

With Ue= air flow Velocity

 

So it seems that the Duke is right and Tornado Cat should buy the book.

 

At Eurocat 2007 or 2008 talking with Glenn Ashby about A-Cat rig's drag, he mentionned the Velocity cube too.

 

Here and there Tom Speer has also mentionned the same cubic dependence.

 

Good reading and Wiki searches

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^^ Not the first time this foil has been seen - or commented on. It curves outboard, presumably to widen the footprint to maximise RM

 

13446389_10206980844059088_509255037_o1.

 

But what's in the wing?

 

Note also in that FP piece as it relates to the rule discussion in this thread: With variable ride control (à la the Moth) and changing foil shapes banned, designers tell us that variable foil bend characteristics may prove the key to the top speed puzzle.

Bloody hell, they've reversed one foil to outfacing? Tricky. But all the eggspurts know that won't work. The silly dingbats?

 

 

No, it's not reversed-its canted bottom out with the tip still pointing inboard........(probably!)

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Sorry to be a bit later, regarding the drag debate: proportional to Velocity squared or cubed ?

 

According to Mark Drela excellent book "Flight Vehicule Aerodynamics" ISBN 978-0-262-52644-9

 

In Chapter 4 / 4.11.4

Regarding the dissipation coefficient (which is close to drag concepts) it is mentionned:

 

The weak dependence of Cd (Dissipation coef) on pressure gradients (assuming fixed transition locations) indicates that the dissipation D(s)= Rho*Ue^3*Cd

 

With Ue= air flow Velocity

 

So it seems that the Duke is right and Tornado Cat should buy the book.

 

At Eurocat 2007 or 2008 talking with Glenn Ashby about A-Cat rig's drag, he mentionned the Velocity cube too.

 

Here and there Tom Speer has also mentionned the same cubic dependence.

 

Good reading and Wiki searches

 

Lift and drag vary as the square of speed!

 

https://www.grc.nasa.gov/www/k-12/airplane/vel.html

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