A-class, "hydrofoils not permitted" violated?

The "banana boards" continue to show excellent speed in higher wind strength. At the "IDB Warnemünde" Bob Baier, which sails a "Nikita" with banana boards, had the scores 1, 1, 3, 1, 4.

But one thing is interesting, are the "banana boards" are hydrofoils or not? If they are the rule "hydrofoils are not permitted" are violated which means that the should have a DSQ.

The purpose of the "banana boards" are both to work as normal centerboards but also to lift and stabilize the boat a bit, and I would call such a device hydrofoil. It is hard to define how much lift a centerboard must give until you start to call it a hydrofoil but if you sail the "banana board" boat at 20 knots a bet the hulls are lifted!

The "banana boards" that the open 60 trimarans use actually lift the bow of the leeward hull at high speeds and that MUST be called hydrofoils or?

/hakan

I guess as the boats were measured at the latest event and allowed to sail they are not hydrofoils!!!!!!

It's going to be interesting to see how that turns out - certainly the rule could use some additional clarification. Again though, one sailor having good results isn't much of a definitive test.

I dont see what the fuss is all about. The Acat class bills itself as a development class, but the class is in a panic over banana boards. They were all in a panic over Ben's solid wing too and that didnt amount to anything significant. Is this a development class or not? If it is, then stop writing rules. If its not, then lock down the rule set so that all foils have to be straight.

Personally, I think the class should leave well enough alone.

They've restricted the underwater foils by max beam in the up and down position and restricted them underwater by not getting closer than 1.5m under the static waterline. The class doesnt need more rules.

Adding banana boards just makes this class more interesting. And its not going to add to the cost of a new boat by any material amount. $50 more carbon in a board isnt going to hurt anything.

Adding or reconfiguring the daggerboard trunks is also not that big of a deal.

Banana boards will probably make the boat more interesting, and faster. Whats wrong with that?

I say bring on the banana's!

It is quite difficult to get rid of hydrofoils in a sail craft, they are needed to keep forces in balance. Any underwater device capable of generating dynamic lift is a hydrofoil. Even the hull generates dynamic lift.

Common daggerboards (straight, vertical and with symetrical section) generate a vertical lift component when the boat heels: upwards if the hull has a bow up attitude, downwards with a bow down attitude.

Rudders also generate a vertical lift component when the boat heels: downwards with weather helm; upwards with lee helm.

What can possibly be banned in a class are "appendages that generate a dynamic lift force component along the axis perpendicular to the plane defined by the waterlines of the two hulls".

Ok, so if my foils lift the boat in another plane, other than perpendicular, then I'm ok?

As you mentioned, all foils generate lift. Its going to be near impossible to regulate good lift vs bad lift.

Furthermore, the original intent of the hydrofoil rule was meant to prohibit was lifting both hulls clear of the water at the same time. If thats the intent, and thats what the rule is meant to prohibit then banana boards are legal.

Bill

That's what I remember too - like I said, a little clarification in the rule may be in order.

Exactly, the current wording actually banned daggerboards, rudders and hulls - and nobody noticed it.

The new definition would ban "appendages that generate a dynamic lift force component along the
axis perpendicular to the plane defined by the waterlines of the two hulls."

This bans everything that generates lift more or less in the same direction the mast points - even when the boat heels. The banana boards generate a lift component in this direction, so they would be banned. Normal daggerboards and rudders are aligned with this "mast" direction, so they don't generate any lift component in the direction "perpendicular to the plane defined by the boat's waterlines", so they are allowed.

If you check the rules at ISAF or at the A-cat webpage there are no rule or measuring guideline that bans that the foils get closer than 1.5 meters. You can have them as close as you want!

/hakan

Someone must file a protest against the boat and as far as I know no one has bothered yet. But now the situation is a bit different and we might see protest from other sailors at the next big regatta.

/hakan

But their Daggerboards are NOT vertical and so they DO generate lift in that direction.

Hulls do not have VERTICAL sides and so they also create some lift (very small amount) in that direction also.

Very difficult rule to word correctly unless they specifically ban bendy boards.

But if a boat has passed measurement it's an A class; I'd expect you could protest that a boat no-longer is in the same state as it was when it was measured, but how can you protest that a boat that has a valid measurement cert is not an A class?, could open a massive can of worms if a boat is declared a valid A class (or any other class that "allows" them), and then protested and then declaired NOT at valid A class - this would potentially negate all measurement certificates and all measurement at the event for this class.


I would have expected that when the measurer originally measured this boat, if they had convcerns, they would relay it to the class administration and they would have decided if these boats were valid A classes.


A decision could be made at a later date to ban them.......

If you see an A-class sweeping by on the downwind in speeds around 15-20 knots and you see that the hull is lifted clear from the normal waterline due to the lift from the hydrofoils I would file a protest immediately. Since the hydrofoil is a grey zone and there are no ways no measure if a device is a hydrofoil or not this must probably be handled on water. There are no "rule" that bans the tips from the foils to be closer than 1.5 meters at the ISAF or A-cat website.

/hakan

Maybe it is just me but this rule is never going to work.

Afterall "hydrofoil" is nothing more then a "waterborn foil" as rudderboards and daggerboards are too. In effect a ruling this simple pretty much disallows all waterborne foils on the A-cat or is incapable of differentiating between traditional rudderboards/daggerboard and vertically lifting foils or parts thereof.

I never understood why this class voting in this rule as I never understood how it could be defended in a real protest for an independent jury (not containing any A-cat officials who thought up this rule)

Wouter

It has been a while since I've been witness to such a situation. ever since the introduction of asymmetric spinnakers on cats we've considered spinnakerless boats on downwind legs as stationary obstructions.

But I'll promise to look the next time an A sweeps by on the downwind leg, might take a while I'm afraid as I don't go over that often ! <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Wouter

Bill,

Why do hate the A-class so much ?

(The reply that was given the last time omeone made similar comments as you did here)

Wouter

I agree Wouter, the big problem is the rule that are very weak and that the next big A-class event is getting closer. Right now I guess that builders and those sailors that has the capability of building boats and foils are trying all kinds of curved foils using a rule that is very weak. This is going to be a disaster for the class unless the officials starts acting fast. And so far they have done NOTHING!!!

There could be a lot of protesting at the next worlds and in worst case a lot of DSQ. A boat could be measured ok but if it is sailed in such a way that it is "hydrofoiling" (whatever that means) then you could protest against it and get it out of the race or?

/hakan

Hakan,

Indeed, I don't envie the situation the A-class is in now. I'm sure it'll find a way out but some difficult times are ahead.




I'm not sure it will be a disaster, but I think we can expect the officials to be behind the curve on this one. I seem to recall that the same officials that came up with the "weak rule" are now the ones to correct the situation. In my life I haven't seen people cgo back on their initial opinion in a timely manner.

Personally, I think the partial lifting foils are an area that is perfect for the A's. It is in line with all developments that they have done in the past, like the carbon mast. As always I believe this to be the strong point of the A's. Especially now when they are no longer the fastest boat on the water or even the fastest singlehander. Two items they used to be in the past. As is commonly known, I truly believe that disaster is around the corner when tehe A's allow themselves to become a tightly regulated (concervatively designed) single sail singlehander. In that attire it will fall behind the other classes that WILL incorporate more and more upgrades like the carbon masts and lightweight construction over coming years. With each upgrade the A's will have less of an advantage and eventually just fall behind. The only way to stay out in front is to develop new stuff and progress the design. That has been the only reason the A's have stayed ahead of the fleet for so long as the 60's A's would have been overshadowed by other classes by the 80's if they hadn't evolved.

Personally, I think that fully lifting foils can be effectively banned, but partial foiling is impossible to ban without tightly regulating the daggerboard setup and limiting the boat to only one daggerboard set and a single rudderboard set. That will add alot of (detail) rules to the A-class rule set which is in direct conflict with the A-cat philosophy. So I think the way out it to go back a step remove to weak ruling altogether and introduce a single new rule that disallows full foiling (clear of water surface like the Moths). Then, let the development begin, with the A's having a new lease on life.

Wouter

I checked with Marstrom and right now ISAF have the "old rule" which stated that hydrofoils are not allowed and nothing more. But there are a new rule which states the tip distance and that the centerboard must be flush with the hull when fully rectracted. That means that you can get 0.4 m lifting surface from each centerboard and rudder and that could be enough to foil. The new rule was sent to ISAF yesterday!

Is would be interesting to know what rule that was in effect during the Europeans, the one at ISAF maybe?

If the statement "hydrofoils are nor allowed" is still there in the new rule you could still file a protest if someone is "flying" but otherwhise we have just made hydrofoiling a lot more expensive since we need to bypass the new rule.

/hakan

DOOM! IT'S ALL BOUND TO FAIL AND FULL OF DOOM!




geeesh...get a life.

Ground Hog Day

From a bunch of people that don't even own Ground Hogs no less.

Quote :This is going to be a disaster for the class unless the officials starts acting fast. And so far they have done NOTHING!!!

I am very close to the A-class official(s) and i can tell you that there is more debate going on then only on this forum .

Does any one know what the lifting difference is between a banana board, an angled straight board and a straight board in the vertical line with the boat. Calculated in theory.

Cheers,

Hans

Get an A-cat Jake instead of that old F18, then you might get a life <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

Hi Hans,
good to hear that things are moving among the officials. Could you post the new rules here or give me a link to the rules. I could only find the old one on the A-cat and ISAF webpage.

I think you could get a lift of roughly 60 kg from a foil that is 0.4 m long and 0.3 meters in width in speeds of 15 knots. The foil is L-shaped in this example which means that only one edge has "end effect problems" of whatevere it is called.

/hakan

Hi Hakan,

I send you a mail.

Cheers,
Hans

Actually I do. I have a very well maintained Boyer Mk IV. <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />

Your signature still says F18. I know, sometimes it's hard to let go.

I thought they were a "fad" anyway.... <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />

doh....better now?

Wouter,
I like the Aclass, but the class keeps talking out both sides of their face - are they are developement class or not? They bill the class as a development class and thats whats gotten them this far, but tightening the ruleset goes against this philosophy.

I agree with your comments that the class need to continue to evolve in order to stay fresh and grow.

By the way, I'm on the Acat website, so I guess I'm not a hater.


http://bp0.blogger.com/_mLM5Q9YpULE/RwDy7AZKX7I/AAAAAAAAAA8/fV8EIv1SsoQ/s1600-h/Bill+Vinning.jpg

Harkan,


There was a clarification diagram on the USACA website under rules, under the measurement heading, which has been recently removed.

Absolutely. And that brings us to the core of the hydrofoil issue:

Dynamic lift occurs to all boats in movement. If it wasn't for the existence of static lift (displacement), banning hydrofoils would make as much sense as banning aerofoils from planes.

I believe the only way to eliminate the dynamic lift components is to keep the boat still. This path leads us to reinventing the buoy.

Interestingly, the conceptual evolution of a displacement (hydrostatic) boat follows almost the same path as the lighter than air (aerostatic) craft:

- At rest they are pure displacement vessels.

- When they move, both inevitably generate some dynamic lift, so speed is improved with streamlined forms. (that explains why a buoy and a baloon are spherical and a boat and a zeppelin are streamlined)

- Then, it is natural that both start using the (inevitable) dynamic lift: they receive apendages for steering, stability and damping (rudders and (flippers or boards)).

- Eventually the dynamic lift starts to assist or replace part or all the flotation. The boat shape becomes apropriated to generate lift (plane) and/or receives hydrofoils, deflection strikes and the like, while the zeppelin becomes thinner and receives wings.

- In the end, the baloon becomes an airplane. Motor boats could just follow the same path, but sailboats have a power limitation (wind) that makes positive flotation indispensable.

Conclusion: is it possible to ban dynamic lift? Hardly. Would it make sense? Only if we want to sail streamlined buoys.

All the best,

If the statement is there, you can win a protest against anyone with a daggerboard or rudder. Really.

Anybody got a copy of ISAF Equipment Rules for sailing?

Look up hydrofoil.

Then look up daggerboard and rudder.

I dont have the document, but as it was just explained to its all defined. Daggerboard is defined as being near the centerline of the hull. Hydrofoil is "not near" the centerline of the hull. Rudder is what you would expect.

So Wouter's interpretation of hydrofoil being a "waterborne foil" and Luiz's assertion that "all foils generate lift" are not valid for the sake of this argument. What matters is the ISAF definition.

So if your daggerboard is not in line with the centerline of the hull, it's a hydrofoil according to ISAF's equipement rules of sailing. The ISAF's definitions are what the measurers use, so its that definition that matters.

Under this definition, any boat with a board that is not in line with the centerline of the hull is not an Acat and cant compete. There are boats competing today that are outside this rule, its just not been enforced.

Seems like canted hulls would also be illegal then, depending on the definition of "ceterline of the hull".

you have two hulls and two centerlines...no problem.

Bill,

My comments earlier were a bit tongue in cheek. I was (am) aware for quite some time that we agree on these points.

It was just when I made similar comments about 4 weeks back I was accused of hating the A-class. My recent comments were a sting to those people.

My appologies if I give rise to a misunderstanding.

Wouter

Ohhhh ! Brilliant Jake. Absolutely bleeding sharp. What a way to beat the rule.

Place the daggerboards under a 10 degress inward angle and have the hull both canted outward by 10, ehh voila according to the whigs at ISAF this boat is not using any hydrofoiling effect to lift it out of the water. Because the starboard daggerboard in in line with the port hull centreline.

Wouter

Two non-parallel centerlines? How do you define centerline?

The diffference between a 6 degrees outward canted symmetrical board (hyped up development of yesteryear) compared to an 6 degrees inward canted symmetrical board when the luff board is fully lifted is 30 kg on a doublehanded F16 with crew on trapeze = (20% of the total saildrive perpendicular to the centreline of the boat.)

The A-class has less righting moment and less saildrive byt the ratio of 20% will still hold. Roughly speaking 15 kg lift on the A in the same situation with the crew trapping.

When allowing boards to go to 15 degrees inward angle the difference becomes 50% of the total saildrive perpendicular to the centreline of boat (= 75 kg on 2-up F16 and 37 kg on A)

Calculating the difference between these boards and the banana boards is not easy to do without agreeing on the specs of the banana board first. For all I know the bananaboard can be twisted towards its tips, making it a symmetical daggerboard near the hull and an permanently positively angled lifting foil at its tips. I will need to know the cord and radius of arc of the banana board and the amount of twist or fore-aft angle in its (hull) slot (= gives incidence angle)

Basically a 0.16 sq. mtr daggerboard with a 0.20 mtr cord (aspect ratio = 4) can rather efficiently
create 75 kg force perpendicular to its plane. It can produce even more force by then the lift drag ratio will be less attractive. So if the daggerboard is L-shaped then a horizontal tip of 0.20 by 0.20 can produce 25% force. Of course we have ignored some efficiency effects here but such a L-shape form can be used as a good first approximation of the curve banaboards which tip reaches 0.20 mtr seperation relative to the centreline of the part in the daggerboard well (assuming this one is on the vertical).

It seems to new A-cat anti foiling rule allows up to 0.30 mtr seperation between the vertical and the tip of the banana board = approx 38% of saildrive transformed into vertical lift (= effective weight reduction craft)

It is not hard to calculate these things using theory; it is just that there are so many factors that need to be fixed/chosen for a value can be produced.

Wouter

I'm pretty sure that the rule reads that each board has to be in line with its own hull centerline.

That was kinda my point. My boat's hulls are canted outward. As you look at the bows, they tilt inward at the top. The daggerboards and rudders are in line with the plane of each hull such that the hull, the board, and the rudder of the leeward hull is nice and plumb when flying a hull...many a-cats are that way (and so is the Nacra 20). I was just pointing out that it's tricky to define all this stuff...including what the vertical plane of a hull is.

One way of doing this is to remove the hydrofoil and min board tip distance rule and require that the centerboards and rudders must be straight and enter and exit the hulls through the centerline and that they are flush with the hull when they are fully retracted.

I guess that solid wings should be stopped also by require a min soft sail area or something like that.

I'm not sure how we should handle the case if someone shows up with a kite on their A-class.....

Or it's maybe time to try to find a single handed one design class, that is light, fast and has big turnout at the regattas. Any suggestions?

/hakan

Hakan

I think you are overreacting.

Ben's solid wing sail wasnt faster. No need to add a rule to legislate solid wings.

And so what if banana boards are faster? Adding them isnt going to be a big deal.

The CClass guys already proved that a foil borne boat isnt as fast as a catamaran with hulls in the water. So, the slippery slope to full foil borne cats wont happen, that experiment has already been done.

I dont see how adding a new curved daggerboard is going to make the boat worse. If you leave it in the current position it will help get the sterns out of the water downwind. Tell me why this is a bad thing?

A foil assist looks to be faster, but again I think thats were its going to stop. Go back and review the CClass experience, and then have a glass of wine and relax, its going to be ok.

I say we get rid of the "no hydrofoil" rule so all those off center daggerboard boats wont be obsolete.

Bill

I just did that.

The daggerboard is defined as "a retractable hull appendage, attached aproximately on the hull centreplane and not rotating, primarily used to affect leeway".

The rudder is defined as "a movable hull apendage primarily used to affect steerage"

The words "hydrofoil" and "foil" are not present in the document.

The axis are referred to the waterplane with the boat in measurement trim, not the waterplane when moving.

I see nothing there very helpful to prevent lift generating devices.

All the best.

The resticted rule set does pretty well to keep this in check - even if they neglected to publish it on the site.

No one seemed to upset about canted boards. A curved one with the same inboard and outbord limits keep the thing virtually identical in net force. It is impossible to restrict the board to be on a hull centerline as you then have to write a rule about the shape a hull can be as there may not be a centerline on an asymetrical hull. If you cant a symetric hull and put the board in straight, they are in effect now canted. Straight foils canted foils and limited curved foils all produce some lift forces. This is why the technical committee removed the hydrofoil reference and in its place restricted the limits of the foils.

These boats have been measured and allowed to compete, so for the time being the argument is moot. There are several petitions being submitted to address this and it will go through the proper procedure to be voted on by the class and potentialy have the rules rewritten to address it.

Say you could build a 50 kg A cat with 25 kg of movable weight added which can be displaced to windwards with a sheet. Would this fit the current A class rules?

It all boils down to the question if the A class really wants to be a development class or if at some point it just wants to abandon certain developments, which requires more and more restrictive class rules. The foil/wing is a secondary, although actual, issue, imho. More issues to come, for shure.

Hmmmn... did the A class experience the recent growth spurt because lots of sailors discovered they liked designing and building faster sailboats to race and joined the class and built or bought the latest design ...

Or did the A class grow because a lot sailors wanted a light weight, high performance single sailed boat with great international sailors at the top of the list and got a boat to play?

I know I waited to see how the class dealt with the foil issue the first time.... If they had voted Yeah on the disruptive foil technology... I would have waited and bought a boat for 1/3 the price.

Re Jake's A-cat AND MINE TOO: "My boat's hulls are canted outward, bows tilt inward at the top. The daggerboards and rudders are in line with the vertical plane of each hull such that the hull, the board, and the rudder of the leeward hull plumb when flying a hull".
So--- the newer boats have the boards tilted in, so that they get lift from the boards when heeled at speed, a big advantage when doing the Wild Thing. To add insult to injury, it appears that inward canted banana boards provide even MORE lift.
By the way---- Lift = hydrofoils

Dave,

Come on...what would you know about the subject?

I have one of those Flyer 2s from Ashby which have the tilted in c/boards. One day got lazy and didn't bring the boards up and found going wild I could push a lot harder up to about 15 knots of breeze. The lift was good enough to help to keep the bows up and allow you to sit a bit further forward. Which meant the stern didn't dig in as much and in chop less rear beam slap. Above 15 knots you would want to bring the boards up as you wanted the sideways slip as the lift generated wasn't enough. But 8 to 15 I always keep down. At the Florida worlds only brought the boards when sailing flat and felt I had really good pace downwind.

This is my experience, and normally sail myself and use a velocitek to guage performance. The averages were better doing what I described for how I sail the boat.

The issue is being put to vote by the membership.

The wording is specifically for or against "curved foils."

This doesnt solve the question of whether straight daggerboards that are not in line with the hull centerline are legal or not.

Bill,

I would think that Canted boards and curved boards would be viewed and treated the same way. That is how I responded to the vote anyway. if canted boards which are already in use throughout the class, then banana boards should be too. As to obsoleting the whole class, my Boyer is probably close to being there anyway. Where I think this will effect the class the most is those who own newer boats.