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Tornado_ALIVE

A Class Worlds - Classic Division

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Looks like the IACA have formally announced the adoption of the Classic Division for the Australian Worlds with the possibility of crowing a WC.

 

I might start looking for a set of C boards for my DNA.  I will continue to sail mostly on the Z10s however may also train and take the C's to the Worlds.  My boat won't be competitive as a Foiler however should make a bloody good C board boat.

 

We have a lot of floaters in AUS and it will be interesting to see how many more come out of the woodwork.

 

http://www.a-cat.org/?q=node%2F1090&utm_source=dlvr.it&utm_medium=facebook

 

Quote

We now have an official definition of the 'Classic' A-Class Catamaran.  IACA President Charles Bueche explains.

Dear class members & fellow sailors,

During the WGM in Sopot, we have accepted the definition of the classic division.

Long-term members who have contributed to the success of the class but not wanting to jump on the latest foiling engines are welcome to sail within this division with their classic boats. The next world championships in Australia has committed to accept and encourage the classic division as a part of the class. And be ready for the best : if the conditions defined by World Sailing (25 entries, 5 countries, 2 continents) are met, we can even crown an “A Class World Classic Champion” !

The definition of the classic division is available 'here' and in the championship rules folder. It’s now up to our classic members to support this initiative.

I wish our southern hemisphere friends a successful sailing season, and those in the “cold and wet” north, a good rest in anticipation of the nice sailing days we will enjoy in 2018.

Kind regards,
Charles and the IACA committee

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Definition of a Classic boat

1. The "classic discipline" A Class must fit all the current class rules.
2. Rule 8 is restricted to daggerboards having either a straight or constant curve axis. 

 

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14 hours ago, Tornado_ALIVE said:

 

I might start looking for a set of C boards for my DNA.  I will continue to sail mostly on the Z10s however may also train and take the C's to the Worlds.  My boat won't be competitive as a Foiler 

 

I've got a pair of pre-foiling DNA rudders you can have cheap.

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6 hours ago, SCARECROW said:

I've got a pair of pre-foiling DNA rudders you can have cheap.

If he doesn't want them and you don't mind shipping... I need a set!

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Hmm, my straight boards won't fit back in the box after conversion but a pair of higher aspect ratio ones might. Who am I kidding, I'm going foiling.

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They'd fit height wise but I have no idea on gudgeon spacing.  I'd think there would be plenty of hinged stocks floating around in a class sail boxes that you should be able to scare something up if they don't.  At this stage yes I'll be at maccrae but can't promise anything.

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If you have an opportunity, could you please measure your stocks. I am 203mm from top of gudgeon to top of gudgeon with an 8mm pin hole.

 

 

IMG_1623.JPG

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I know the Boyer stocks won't fit into those pintails. I think you are better off modifying the rudders to fit the stocks rather than vice versa. It's one hole in the rudder.

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Nope they don't fit.  As Sam says, its only 2 holes in the rudders and saves you changing out any of the rest of your steering assembly.  They even come with a nice bag.

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If sailing c boards in the classic div, you may want to consider winglets on the rudders. They featured on the top Aus As prior to foiling.

Completely killed those spectacular cartwheels when C boards trip though....

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I'm wanting to get a new sail for my 'Classic' A Class Catamaran and was wondering if I should go for a decksweeper sail or stick the current design?

I would like to hear people thoughts and also the ones who have changed their sails whether it's made a difference.

Thanks 

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The decksweeper on a classic is an interesting question. Your weight and what breeze you sail will have an influence. I had a classic and foiler for a couple of years and swapped rigs a lot. The DS was better on the foiler up and down wind but leave that aside as that's not your question. At 95kg I found Landy DS very good upwind in all breeze. The stronger the breeze the greater the advantage it had over a Landy Classic sail. Downwind I had no problem in very light wind and in 10 knots plus. I was a bit vulnerable in 6 to 10. I used the DS in the last nationals and got a good result in admittedly medium to fresh breeze. I've used Brewin and Ashby sails a lot and recommend them as well. Even better if you use a sealed tramp with the DS. 

I personally think a slightly bigger DS head is a good idea for a classic. I'm putting a new classic on the water soon and it will have a Landy DS with a slightly bigger head and a solid tramp. If you're planning on doing the Hervey Bay Worlds it's unlikely you'll have trouble with really light air so a DS is a good option. 

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The lighter the wind, the bigger the lift coefficient of the rig and the bigger the advantage of a DS sail compared to a no DS sail, as induced drag coef is function of Cl^2.

 

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Per classic aero theory, yes. However one also has to remember that we are sailing in a boundary layer, and there is more wind aloft than at the deck of a 30' rig. On the foiler, one cannot accept the increased heel that the top of the sail generates in virtually any condition above 7 kts of wind speed, so the heads have become smaller and smaller, dropping below 800mm (look at latest Brewin and Mischa A-Cat DS's). Now compare these to what the latest F18 DS sails are using-they are in the 750-900mm range for the head size with pretty short foots, ~1m, which leaves a nice hole for tacking and gybing with 2. One doesn't quite need that on an A Cat but more space does make for easier maneuvering!

Our opinion is the 2016 Glaser A-Cat DS, which has a pretty big head (I have the actual number somewhere, but IIRC its ~800mm), is a fast sail in up to 10kts of breeze. This is based on foiling test data but the non-foilers are very surprised at how well this works on the Hall Medium Flexi rig in the light conditions. I would happily recommend this sail to a classic sailor looking for a new sail. I am sure the Landy WnW has is similar.

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3 hours ago, Erwankerauzen said:

The lighter the wind, the bigger the lift coefficient of the rig and the bigger the advantage of a DS sail compared to a no DS sail, as induced drag coef is function of Cl^2.

 

Correct, but....... The decksweeper on the foilers does 2 things. It is aerodynamically more efficient and it lowers the centre of effort of the rig, which unloads the foils which makes foiling easier. On a classic, you need to pop a hull to go fast downwind and the lower CoE is why WnW reports problems in 6-10 knots. You cannot make a decksweeper without lowering the CoE unless your sail ends up looking silly, so it will be interesting to see if a compromise can be found. I suspect it is easier in Australia where we tend to do less lighter wind sailing.

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The lower CoE is an indirect consequence of the DS solution

With DS your lift distribution along the span is supposed to vary from elliptical (when you can use the max righting moment, without being overpowered) to triangular (when overpowered), in order to minimize your induced drag. 

The elliptical area distribution one can observe on new A-Cat DS sails, is just the Apparent wind gradient's consequence, necessary tu put all square feet at full use for downwind leg when apparent wind is lower and hence optimization of the sail plan is more important*.

From basic gemotry we know that the center of gravity of an ellipse is at 42% height and a triangular one is at 33% height.

Compared to a classic sail, where CoE is probably around 48% height, for sure, there is a loss in righting moment. But....

For similar A-Cat sails (I mean equivalent 2D sections and 2D performance), with a DS sail, the Effective lift coefficient will  rise from  0.76 to 0.84,  so you have 0.84/0.76=1.11  around +11% extra power, everything else equal.

 DS sails allow you to have a powerfull section at the bottom of your sail, as it will not be wasted in induced drag vortex.

I think the loss in righting moment is more the consequence of the elliptical area distribution than the consequence of DS choice, even if both use to come together as above-mentionned

A taller rig might be a solution to address this little disadvantage in light wind.

A DS sail with a little less elliptical area distribution and a little more sqared head should be a reasonnable trade-off for non foiling boats which have different requirements like sailing Wild Thing downwind or flying a hull windward as soon as possible.

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From an outside point of view....

As far as I can tell a well set up ""classic" boat will still foil down wind.  Think of the ETNZ boats at the Takapuna worlds they were all foiling off the wind and fit within the description of "classic", add modern rigs, platforms and rudders and that performance should improve.  An appropriately "tweaked" DS main would be part of that package.

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11 minutes ago, SCARECROW said:

Think of the ETNZ boats at the Takapuna worlds they were all foiling off the wind and fit within the description of "classic", 

They did not fit within the classic definition. To be a classic, you have to have one hull in the water at all times, so foiling off wind means they are not classics.

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7 minutes ago, SCARECROW said:

I hadn't seen the "I swear not to foil" part of the rule.

Not at all contentious......... "sorry, I didn't mean to foil. I was only foiling for a moment, it was perfectly safe, i didn't gain an advantage and I stopped foiling as soon as I could". Or "he foiled" "no I didn't, I launched off a wave" :D

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So to clarify, something like a late model well setup DNA C board boat with late gen flexi boards that support trapping downwind is considered a classic? Further, the mode where this has the same proportion of hull in the water that Macif does reaching/downwind, this is still considered classic mode?

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2 hours ago, SCARECROW said:

From an outside point of view....

As far as I can tell a well set up ""classic" boat will still foil down wind.  Think of the ETNZ boats at the Takapuna worlds they were all foiling off the wind and fit within the description of "classic", add modern rigs, platforms and rudders and that performance should improve.  An appropriately "tweaked" DS main would be part of that package.

Slight correction here. The "ETNZ" boats and some others like Nathan Outteridge's at the Takapuna Worlds weren't Classics. Some ran J,s and some Z2. Point 2 of the definition of a classic requires boards to be either straight or constant curve axis. It's not possible to foil a boat with straight boards. Foiling isn't jumping off a wave. Cant them within the 750mm rule and you can get a little lift but not foiling. Constant curve C's can lift out of the water but certainly not under any real control. I have seen that and done it on a C board A. Also the Nacra 17 C boarders lift out but aren't under control. The new definitions and competitor's declaration seem to cover it. 

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3 minutes ago, Tornado_ALIVE said:

This should clear it up.  This was the link in my first post.

Read the deceleration 

 

IMG_1905.PNG

Yes and as sailing is a self regulated sport it will be applied in the time honoured way. Any transgressors will be taken behind the shed and have the shit belted out of them - to quote Bags.

 

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22 hours ago, WetnWild said:

Slight correction here. The "ETNZ" boats and some others like Nathan Outteridge's at the Takapuna Worlds weren't Classics. Some ran J,s and some Z2. Point 2 of the definition of a classic requires boards to be either straight or constant curve axis. It's not possible to foil a boat with straight boards. Foiling isn't jumping off a wave. Cant them within the 750mm rule and you can get a little lift but not foiling. Constant curve C's can lift out of the water but certainly not under any real control. I have seen that and done it on a C board A. Also the Nacra 17 C boarders lift out but aren't under control. The new definitions and competitor's declaration seem to cover it. 

Yes BUT elevator winglets are class legal in the A, so c-board boats could foil and do so in control in the right conditions.

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5 minutes ago, samc99us said:

Yes BUT elevator winglets are class legal in the A, so c-board boats could foil and do so in control in the right conditions.

not if you've signed a piece of paper that says they won't.  I hope the class does what they hope rather than seeing people looking at it as a strawberry (low hanging fruit) and spending a lot of time and money getting as close as possible to foiling without actually foiling.

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43 minutes ago, SCARECROW said:

not if you've signed a piece of paper that says they won't.  I hope the class does what they hope rather than seeing people looking at it as a strawberry (low hanging fruit) and spending a lot of time and money getting as close as possible to foiling without actually foiling.

I'm playing devils advocate and I hope this is the case as well as it really keeps the class alive. Including both boats at major events has proven very successful in the U.S, I believe the A is now the largest class in terms of regatta attendance etc.

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1 hour ago, SCARECROW said:

me too but I think they should have gone back 2-3 more years in there definition of "classic"

I can only assume you mean restricting to straight boards. That was certainly considered in the formative stages of this change. However it is now eight years since straight boards were outdated in development and are rarely used these days in World and National Titles. They are just not competitive in most conditions at those events. That would have left a huge number of C board boats in limbo around the world and I doubt such a proposal would have been endorsed by the membership through national presidents at a World AGM.

In Aus we have recognised out of date boats at the Nationals with the awarding of the Presidents since last century. At first it was low profile boards and alloy masts, later straight boards, and for the last four years C boards. Club racing has the Vintage yardstick provided by Australian Sailing for the really old school boats. 

The introduction of the Classic discipline is an initiative in good faith to engage and embrace the whole A Cat community around the world. It is the result of a huge amount of work by the World Executive and detailed discussion and endorsement by World Sailing. It was enthusiastically endorsed by class membership through country presidents at the most recent AGM. It is now up to us as class members to make this work and demonstrate to WS and the sailing community generally that we are an inclusive group. Of course we strongly endorse foiling and we have now found a way to recognise and include those preferring not to go that way.

 

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5 hours ago, SCARECROW said:

not if you've signed a piece of paper that says they won't.  I hope the class does what they hope rather than seeing people looking at it as a strawberry (low hanging fruit) and spending a lot of time and money getting as close as possible to foiling without actually foiling.

That would be perfectly legal and occurs now. 

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5 hours ago, samc99us said:

Yes BUT elevator winglets are class legal in the A, so c-board boats could foil and do so in control in the right conditions.

I'm intrigued Sam. Have you seen that? The Flexi C boards were hyped here in 2013 but nobody could get them to foil as we know it. There was hopping out but no foiling under control. And some very high level sailors were trying. Since C boards were introduced in 2009 and winglets in 2012, I've sailed plenty of Worlds and Nationals and never seen the Olympians and AC sailors we get able to properly foil such a boat. I think there is little hope for you and I!!!!!

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But please sir, we were told that C boards were the foiling holy grail of the time, the mere thought that C boards were actually a  total waste of time and cost must be pretty gauling to all those who bought them then.

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28 minutes ago, Waynemarlow said:

But please sir, we were told that C boards were the foiling holy grail of the time, the mere thought that C boards were actually a  total waste of time and cost must be pretty gauling to all those who bought them then.

Sounds like you haven't used them. Not foiling but clearly superior to straight boards downwind on an A. 

Also the choice for the world youth boat as a trainer for the Olympic foiler. Not galling for most people. 

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I raced a C-board boat with winglets back at 2015 NA Midwinters. It did not have sliders for the boards, nor was I really confident to push the boat hard downwind from the wire etc. It didn't have a propensity to foil, I will give you that.

I am comparing that experience to my F20c experience. That latter had sliders installed and would easily foil downwind with the kite up in 12-14kts of breeze. I believe it would have been somewhat stable with t-foil rudders and an Olympic helm. I also believe the same is true of the N17-the top guys were full foiling without any rudder foils on the Mk. 1's.

All that being said, the A is a different animal and the 1.5m rule limits the curvature of the C-boards. The C's are also inherently prone to slipping laterally with no winglet at the tip and aren't particularly heave stable. I do think the top C-board boats will be running sliders and quality asymmetric boards with t-winglets. Maybe they can fully foil in the right conditions but with the sliders they could go to minimum lift.

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1 hour ago, WetnWild said:

Sounds like you haven't used them. Not foiling but clearly superior to straight boards downwind on an A. 

Also the choice for the world youth boat as a trainer for the Olympic foiler. Not galling for most people. 

Ummm you don't get what I meant. I had argued for some years that the 7 degree allowance on a straight board within the F16 rules maybe as good as a C board without all the expense, from my own experience I was getting semi foiling but then I had T foils as well. Most A catters were totally derisory and maintained that C boards were the only way of foiling and that straight boards were now past history.

History now tells us that C boards were at best modicum and that were really only a learning tool to get to Z boards and a method to get around the max width with the boards up. Man that's a huge budget blown on something that most would have been spent on training and time on the water. I guess that's just like an awful lot of deja vu.

Exclude the boards on max width and you may have a very nice semi foiler just like the F16's. 

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Reading people posts......... the decksweeper sail is the way to go.

With the development there's some good quality (old) sails around that will become obsolete.

Curveball question, If you took one into sail maker and got it recut into a decksweeper would it work as well as a new one?

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2 hours ago, NZL255 said:

Curveball question, If you took one into sail maker and got it recut into a decksweeper would it work as well as a new one?

Not a curveball at all. If you took a new conventional sail and then recut it into a decksweeper it will work pretty well. We know this because it is exactly what Glenn Ashby did 2 years ago and he won thew worlds with it.

The biggest problem is that for most, they are going to take an already well used conventional sail and recut it. It will only be as good as a well used decksweeper and is it a good spend of money, because the recut is probably a third of the cost of  a new sail.

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13 minutes ago, knobblyoldjimbo said:

Won't you have to chop the top of the mast off for a decksweeper?

 

No, because the top of most decksweepers is smaller and you take some off the leech as well.

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3 hours ago, NZL255 said:

Reading people posts......... the decksweeper sail is the way to go.

With the development there's some good quality (old) sails around that will become obsolete.

Curveball question, If you took one into sail maker and got it recut into a decksweeper would it work as well as a new one?

I've looked into this a good bit. I have what amount to 2 brand new F18 non decksweeping mains (and a third, a new DS). Can't sell the old new ones so I figured I'd get them converted...well I've had two well known and fast sail makers tell me yes only to not get back to me with quotes etc. My local sail maker, whose time is limited, guessed it would run $800-$1000 for the recut. I've heard of less being spent but because of the mods to the top of the sail and the leech,the battten pockets have to be re-done. Also, a new luff tape gets installed. Estimates are basically 6-8 hours for a re-cut vs. 10-12 hours for a new sail. Just doesn't make sense unless you are a sailmaker.

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12 hours ago, samc99us said:

I raced a C-board boat with winglets back at 2015 NA Midwinters. It did not have sliders for the boards, nor was I really confident to push the boat hard downwind from the wire etc. It didn't have a propensity to foil, I will give you that.

I am comparing that experience to my F20c experience. That latter had sliders installed and would easily foil downwind with the kite up in 12-14kts of breeze. I believe it would have been somewhat stable with t-foil rudders and an Olympic helm. I also believe the same is true of the N17-the top guys were full foiling without any rudder foils on the Mk. 1's.

All that being said, the A is a different animal and the 1.5m rule limits the curvature of the C-boards. The C's are also inherently prone to slipping laterally with no winglet at the tip and aren't particularly heave stable. I do think the top C-board boats will be running sliders and quality asymmetric boards with t-winglets. Maybe they can fully foil in the right conditions but with the sliders they could go to minimum lift.

Yes I thought you might have been referencing other boats for your actual experience. Most C board A,s have had adjustable sliders since 2009 so we know what that can do. Assymetric  boards were tried early on but worked against each other when both down with drag. Lifting and pushing down on tacks  and gybes was too slow on a one person boat so that direction went nowhere. We are going with symmetrical at this stage on the new boats.

My direct feedback from a Rio multihull coach was the boats were a bastard to sail and any foiling was unpredictable, intermittent and not particularly fast. Probably explains why the configuration was quickly changed for the next cycle. 

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1 hour ago, samc99us said:

I've looked into this a good bit. I have what amount to 2 brand new F18 non decksweeping mains (and a third, a new DS). Can't sell the old new ones so I figured I'd get them converted...well I've had two well known and fast sail makers tell me yes only to not get back to me with quotes etc. My local sail maker, whose time is limited, guessed it would run $800-$1000 for the recut. I've heard of less being spent but because of the mods to the top of the sail and the leech,the battten pockets have to be re-done. Also, a new luff tape gets installed. Estimates are basically 6-8 hours for a re-cut vs. 10-12 hours for a new sail. Just doesn't make sense unless you are a sailmaker.

Agree 100%. Glenn only got away with it because his labour was free to himself and he knows what he's doing with an A sail. 

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2 hours ago, knobblyoldjimbo said:

Won't you have to chop the top of the mast off for a decksweeper?

 

You might be getting mixed up with the short rigs tested by a few leading sailors in the last year. They chose not to use them in Sopot but may be something to look at in 6 weeks time. Not for the average punter to jump on at this stage. 

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11 hours ago, Waynemarlow said:

Ummm you don't get what I meant. I had argued for some years that the 7 degree allowance on a straight board within the F16 rules maybe as good as a C board without all the expense, from my own experience I was getting semi foiling but then I had T foils as well. Most A catters were totally derisory and maintained that C boards were the only way of foiling and that straight boards were now past history.

History now tells us that C boards were at best modicum and that were really only a learning tool to get to Z boards and a method to get around the max width with the boards up. Man that's a huge budget blown on something that most would have been spent on training and time on the water. I guess that's just like an awful lot of deja vu.

Exclude the boards on max width and you may have a very nice semi foiler just like the F16's. 

We may be talking at crossed purposes. 

We used canted high profile boards for some years 2006 - 2009 in the German Flyer 11 and Geltec Flyer 11. They were faster than virtical boards but totally blown away by C boards downwind. I don't think F16 is a good reference point for a fast paced development class like A's. They seem to be a small niche group with highly controlled development. Just had a Worlds cancelled due to lack of interest. 

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15 hours ago, WetnWild said:

Yes I thought you might have been referencing other boats for your actual experience. Most C board A,s have had adjustable sliders since 2009 so we know what that can do. Assymetric  boards were tried early on but worked against each other when both down with drag. Lifting and pushing down on tacks  and gybes was too slow on a one person boat so that direction went nowhere. We are going with symmetrical at this stage on the new boats.

My direct feedback from a Rio multihull coach was the boats were a bastard to sail and any foiling was unpredictable, intermittent and not particularly fast. Probably explains why the configuration was quickly changed for the next cycle. 

WnW,

  Funny, those adjustable sliders never really populated the A-Cat fleet in the U.S, at least not to my knowledge. I suspect most of the fleet hadn't seen them until the 2012 worlds, but I'm by no means an expert or class historian. The boat I sailed and the local boats with C-boards don't have sliders. I agree that for a singlehander a good symmetrical board makes the most sense. On the F20c we weren't tacking the boards but I do think it would be necessary in a competitive racing environment like the N17's proved, though A Cat sailor Niles Bunkenburg (Nikita) designed the F20 c boards supposedly, so they may be different/better/worse than the N17 mk. 1's.

Direct feedback from Rio sailors agree with your coaches feedback...the boat would have been fine with t-foil rudders and the Mk. 2's aren't a perfect solution either. Regardless, nothing to do with classic A's, those have been pretty well sorted now with the C-boards and the t-foil rudders. Should be a bit faster too with the DS :)

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17 hours ago, WetnWild said:

You might be getting mixed up with the short rigs tested by a few leading sailors in the last year. They chose not to use them in Sopot but may be something to look at in 6 weeks time. Not for the average punter to jump on at this stage. 

Having sailed against the short rig quite a bit, I would say it is slower in most conditions on a foiler. Only benefit I can see is lower COD and COG result in less pitching moment. Would not work at all on a classic as far as I can see. 

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 I converted my Geltek from canted boards to C's and sailed it a couple of years that way - it was a pitchpole machine.  Later I added winglets and sliders and it made a huge difference.  Upwind with the board set neutral, it sailed like it was on rails. Downwind on big air days, I would pull the boards back until the bows lifted and could send it as hard as you wanted.  I can't say that I ever pitchpoled it again.  The current owner is out their kicking ass in the classic fleet with it.

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2 hours ago, Rawhide said:

Having sailed against the short rig quite a bit, I would say it is slower in most conditions on a foiler. Only benefit I can see is lower COD and COG result in less pitching moment. Would not work at all on a classic as far as I can see. 

Yes sorry I meant to say I had only seen them on foilers. One of our mutual sailing mates told me he had the shits with them and was throwing his in the bin!

The standard height seems the choice for Classics. I have put my money where my mouth is on that one. 

On the foilers one very prominent person has a view that taller might be better. I haven't heard any action there though. 

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I certainly wouldn't look at short rigs for the classics. The jury is still out on them for foilers. I hear such mixed reports. Stevie Brewin tells people he is sure it is quicker in a breeze, but the proof of his views is that he didn't use it at the worlds. Part of the issue is that Stevie and Bundy didn't use a purpose made short rig for testing but instead had a repaired mast cut short. I cannot see how they could have developed a sail to fit a purpose made short mast like that. I think they have both brought short masts back to Australia, but those are the only purpose made masts. It a;ll seems too much of a risk for little to no gain and I certainly won't be cutting down a mast just to find out if it is good.

 

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On 11/18/2017 at 5:49 AM, Erwankerauzen said:

The lower CoE is an indirect consequence of the DS solution

With DS your lift distribution along the span is supposed to vary from elliptical (when you can use the max righting moment, without being overpowered) to triangular (when overpowered), in order to minimize your induced drag. 

The elliptical area distribution one can observe on new A-Cat DS sails, is just the Apparent wind gradient's consequence, necessary tu put all square feet at full use for downwind leg when apparent wind is lower and hence optimization of the sail plan is more important*.

From basic gemotry we know that the center of gravity of an ellipse is at 42% height and a triangular one is at 33% height.

Compared to a classic sail, where CoE is probably around 48% height, for sure, there is a loss in righting moment. But....

For similar A-Cat sails (I mean equivalent 2D sections and 2D performance), with a DS sail, the Effective lift coefficient will  rise from  0.76 to 0.84,  so you have 0.84/0.76=1.11  around +11% extra power, everything else equal.

 DS sails allow you to have a powerfull section at the bottom of your sail, as it will not be wasted in induced drag vortex.

I think the loss in righting moment is more the consequence of the elliptical area distribution than the consequence of DS choice, even if both use to come together as above-mentionned

A taller rig might be a solution to address this little disadvantage in light wind.

A DS sail with a little less elliptical area distribution and a little more sqared head should be a reasonnable trade-off for non foiling boats which have different requirements like sailing Wild Thing downwind or flying a hull windward as soon as possible.

I don’t think you can leave junction drag and pressure gradients out of this discussion. Right angle end plates are often inefficient, and useful in only limited situations.

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Victorian Catamaran Championships last weekend As were largest class with 17 starters. Included 7 classics and 10 flying. Regatta scored As as one class on yardstick. First day was 2 races less than 6 knots mostly about 4 knots. Classics to the fore!

Except that Glenn was there, foiled in that wind and lapped a few flyers stuck to the water. Said he was rusty.

Next day was windy mostly around 18 knots. Glenn and Bradshaw ;-) foiling uphill, spectacular but sometimes in the wrong direction as it shifted. 2 races, Glenn won neither. Brayshaw got one bullet and Brew in a very quick converted dna the other.

Glenn won the class and maybe he was rusty by capsizing in a foiling gybe. Thats what weve got to look forward to when the skills are polished.

Point is that Classics were there in numbers and figured in results with a fourth place overall to GGM Ross Lloyd in DNA C with exploder rudders and winglets. Non DS sail

New classics on order for HB Worlds. Great sailors in both divisions. Great move by IACA.

 

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As far as I remember, I never saw or heard about Glenn  capsizing, either with A-Cat or HC Tiger with Darren,

So he is a human being after all, that is a good new, I always thought he was an ET

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Mookiesurf,

Pressure gradient will improve the righting moment a little bit.

Windward of the sail foot you have hight pressure which push downward on the trampoline if it is  airproof

Leeward of the sail foot you have a low pressure which sucks up the trampoline,

Both create a moment which can be added to  the crew  righting moment.

Right angle endplate are probably not that efficient when settled at the top of the mast, but for DS it is a no brainer whether you consider A-Cat or even F18 where the jib does not take advantage of the tramp's end plate effect.

Junctiion drag is not that important, if you know how to compute it do not hesitate, but I think by junction drag could be a kind of "separation drag" as the boundary layer at the corner between tramp and footsail is under double stress and it is likely to separate before the sail leech.

But fortunatly with the apparent wind twist (especially downwind) the bottom of the sail experience lower AoA, so less opportunity to see separation.

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SonofaGun,

In Bermuda he was not sailing a beach cat.

Did Glenn mentionnned you he had decksweeper project on his backburn as soon as 2012 ?

But he was a little busy elsewhere to develop a user-friendly DS sail.

Fair wind Mate

Erwan

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Erwanker AFAIR Mischa developed the DS and revealed in Holland nats before Punta Ala. Glenn was 2nd in holland, copied DS and won Italy worlds.

He has been busy and hasnt been on an A since then until 2 weeks ago. His rusty is measured differently to ours.

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Myself and another foiling A came around the top mark on day one in about 6 knots running deep.  Ashby came around behind us (a lap ahead) heated up and foils right around us.  I jumped out and tried it only to loose 1/3 of a leg in no time :D

The second day in breeze, mitchellsailor tacked next to me, then began foiling upwind (only sailed his new A about 1/2 dozen times) and pulled away from me like a train.

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Goodall brother had designed the first A-Cat DS with a wishbone-boom and a stepped leech, just like Pete Melvin at Takapuna. GA has been working with Greg and sailing his boat and sails in the middle 90's

This design, if it works well windward as the apparent wind twist is tiny, it is another story Downwind as bottom  part of the sail (the stepped part) does not produce significant lift due to too low AoA.

You probably remember that ETNZ  AC72 was training in New-Zeland at the end of 2012, without DS wing, and as soon as serious things started, all AC72 had closed the gap under their wingsail.

So, do you honestly believe that a specialist of A-Cat rig, working as a wing trimmer in a AC Team, always in touch with the best CFD engineers, could have missed such an evolution ? 

Or do you think he had other priorities ?

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I should have add.

As the stepped leech does not work well downwind, a 45° slope leech in the bottom (below the clew) makes it much better, and I would not be surprised if somebody would add a rubber between the center of the trampoline and the aft /bottom corner of the leech/footsail , in order to meet better the AW twist.

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24 minutes ago, Erwankerauzen said:

Goodall brother had designed the first A-Cat DS with a wishbone-boom and a stepped leech, just like Pete Melvin at Takapuna. GA has been working with Greg and sailing his boat and sails in the middle 90's

 

Well not exactly. The DS that Greg made debuted at the 1990 Nationals at Lake Cootharaba. It also had a flat top as we called it then as opposed to a pinhead. The DS aspect was immediately dropped and forgotten for a long time. The flat top aspect was immediately adopted and within a year almost everyone had one. Glenn was 13 at the time and didn't have any involvement. 

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2 hours ago, Sonofagun said:

Victorian Catamaran Championships last weekend As were largest class with 17 starters. Included 7 classics and 10 flying. Regatta scored As as one class on yardstick. First day was 2 races less than 6 knots mostly about 4 knots. Classics to the fore!

Except that Glenn was there, foiled in that wind and lapped a few flyers stuck to the water. Said he was rusty.

Next day was windy mostly around 18 knots. Glenn and Bradshaw ;-) foiling uphill, spectacular but sometimes in the wrong direction as it shifted. 2 races, Glenn won neither. Brayshaw got one bullet and Brew in a very quick converted dna the other.

Glenn won the class and maybe he was rusty by capsizing in a foiling gybe. Thats what weve got to look forward to when the skills are polished.

Point is that Classics were there in numbers and figured in results with a fourth place overall to GGM Ross Lloyd in DNA C with exploder rudders and winglets. Non DS sail

New classics on order for HB Worlds. Great sailors in both divisions. Great move by IACA.

 

Love your work Sonofa. That Bradshaw bloke must be ok. 

22 A's at the Qld Cat Challenge a few weeks ago and also the biggest fleet. Classics did well too apart from a couple of those pesky DNA things. Seems it's emerging that about half the fleets are Classics. Looking good for the Worlds next year. 

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W&W,

Sure Glenn was not sailing A-Cat yet ,but Paper Tiger,.

I don't know if Greg Goodall used to make Paper Tiger sails in the 80's 90's?

Both were living in Bendigo, and there was water in the lake at these times.

Cheers

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2 hours ago, Erwankerauzen said:

Mookiesurf,

Pressure gradient will improve the righting moment a little bit.

Windward of the sail foot you have hight pressure which push downward on the trampoline if it is  airproof

Leeward of the sail foot you have a low pressure which sucks up the trampoline,

Both create a moment which can be added to  the crew  righting moment.

Right angle endplate are probably not that efficient when settled at the top of the mast, but for DS it is a no brainer whether you consider A-Cat or even F18 where the jib does not take advantage of the tramp's end plate effect.

Junctiion drag is not that important, if you know how to compute it do not hesitate, but I think by junction drag could be a kind of "separation drag" as the boundary layer at the corner between tramp and footsail is under double stress and it is likely to separate before the sail leech.

But fortunatly with the apparent wind twist (especially downwind) the bottom of the sail experience lower AoA, so less opportunity to see separation.

Thanks Erwan, excellent.

It would be useful to separate out the gains and losses. In other words,  are the gains from a sealed tramp primarily from drag/turbulent flow reduction around the tramp, or from improved pressure distribution on the sail?

There is no escaping junction drag as the different airflows and pressures pile up and crowd each other where two surfaces meet at an angle.  Look at carefully sculpted aircraft winglets, which are simply well engineered endplates, and have angles much greater than ninety degrees.  I wonder if the convex decks of the AC boats may have mitigated junction drag.

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7 hours ago, mookiesurfs said:

It would be useful to separate out the gains and losses. In other words,  are the gains from a sealed tramp primarily from drag/turbulent flow reduction around the tramp, or from improved pressure distribution on the sail?

I think it is far more complex than that. With a conventional sail, the fuller you make it low down, the more the air will try to leak under the sail to equalise the pressure, rather than flow around the camber, which is why we make the sails relatively flat in the base. When you go for a decksweeper, because air cannot leak under the sail, you can run far deeper camber, making the sail more powerful low down, which helps lower the centre of effort further. I think some try to make the base of their decksweeper too flat and miss the big opportunity.

There is an interesting question about the tramps. The top guys are using airtight materials, but some with older boats are using their old conventional tramps, which do let some air and water through. How much are they missing out on the benefits because of air flowing through the tramp?

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9 hours ago, Erwankerauzen said:

W&W,

Sure Glenn was not sailing A-Cat yet ,but Paper Tiger,.

I don't know if Greg Goodall used to make Paper Tiger sails in the 80's 90's?

Both were living in Bendigo, and there was water in the lake at these times.

Cheers

All true Wankoz but I don't know about Paper Tigers. Never understood a boat you can't trapeze. 

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Sorry for firing more questions.

I've spoken to some top A Class Catamaran sail makers about a decksweeper for a classic.

As we know they make fantastic sails are full of knowledge and are great at selling their products :-)

Only thing that there are two types of decksweeper sails boom and boomless. Again sail makers will personally tell you what they think best suits. I would like to read your thoughts on this topic.

Boom or boomless??

 

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Pick a sail maker then follow their recommendation with regards to boom.  If you don't like their recommendation change sail makers.

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Go boomless. Stevie won the Worlds with one and showed they are quick.  Many others like Bundy and Brayshaw have also shown they are quick.

Goodall was producing F18 DS with a boom and after some RnD, has also gone boomless.

Booms for DS on F18's and A's have been known to cause mast failure.  Other than somewhere to put your starting watch, I do not see the advantage of the boom.

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Boomless

+ cheaper, quick to rig, reduce weight boom and spanner, old masts dont break at gooseneck, rotation automatic until overpowered

- controll of foot, mainsheet load, 

Tried both, wouldnt go back to a boom

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21 minutes ago, Sonofagun said:

Boomless

+ cheaper, quick to rig, reduce weight boom and spanner, old masts dont break at gooseneck, rotation automatic until overpowered

- controll of foot, mainsheet load, 

Tried both, wouldnt go back to a boom

Me either,

What say you ACS?

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I am boomless for various reasons. I have a Brewin and Stevie told me to go boomless so I did and it has saved me money not having to buy a boom. Wishbone booms attached to the side of the mast put loads on that the mast isn't designed to take which has led to a number of mast breaks, including Fiberfoam's own Scott Anderson. Most important in this discussion, I cannot see any disadvantage with a boom. Stevie says it is faster, but I am not really in a position to prove that, so all i can say is that it isn't slower

What I don't understand is the attitude of many of the sailmakers. They won't even try boomless. Credit to Goodall for being open minded and trying it. I really did expect that we would have seen Ashby, Landy, Bryt and Mischa try boomless but no, they simply say it isn't as good and don't even try it. I know that Stevie has tried both and still occasionally tests with a boom as a few of his customers insist, but he never seems tempted to go for one. He might be looking for a gimmick to sell sails, but I don't think he would ever do that at the expense of his personal boatspeed. It seems obvious to me that if the only sailmaker who has tested the 2 properly goes for one and uses it himself when he has the choice, that boomless must be OK. Then consider Darren Bundock trains with Stevie so will have also tried boom and boomless. He goes boomless and I cannot see him doing so if he wasn't convinced.

The problem comes when you want to go boomless but don't want a sail from Stevie. He isn't the only sailmaker in the class and we have seen good performances from Ashby, Mischa, Bryt and Landy sails and their boom sails. I don't think you can just take the boom off

In conclusion, boomless is better but go with whatever sailmaker you want to deal with

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On 28/11/2017 at 12:33 AM, WetnWild said:

Well not exactly. The DS that Greg made debuted at the 1990 Nationals at Lake Cootharaba. It also had a flat top as we called it then as opposed to a pinhead. The DS aspect was immediately dropped and forgotten for a long time. The flat top aspect was immediately adopted and within a year almost everyone had one. Glenn was 13 at the time and didn't have any involvement. 

Well not exactly. The flat top debut at lake cootharaba was in 1988 was built by Ryan sails with Barry Marmion inspiration and helm. It had a conventional boom with gooseneck at deck level so wasnt a true decksweeper. Came second. Greg copied the square top and most of the fleet swapped in 1989 at Belmont. First DS with wishbone boom on A I recall was by Tim Daddo of Macquarie Innovation fame about 10 years ago. Glenn joined greg in mid 90s as apprentice was given a hand me down A (a pig of a boat aptly named, Its life Jim, But Not As We Know It) and won the first A regatta he entered, the worlds.

There endeth the lesson WnW

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1 hour ago, Sonofagun said:

Smart arse

I agree with your opinion of Abitch. 

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1 hour ago, Sonofabitch said:

Well not exactly. The flat top debut at lake cootharaba was in 1988 was built by Ryan sails with Barry Marmion inspiration and helm. It had a conventional boom with gooseneck at deck level so wasnt a true decksweeper. Came second. Greg copied the square top and most of the fleet swapped in 1989 at Belmont. First DS with wishbone boom on A I recall was by Tim Daddo of Macquarie Innovation fame about 10 years ago. Glenn joined greg in mid 90s as apprentice was given a hand me down A (a pig of a boat aptly named, Its life Jim, But Not As We Know It) and won the first A regatta he entered, the worlds.

There endeth the lesson WnW

I bow to your superior memory of the sail configurations and Greg's lack of involvement.

I'm not so sure about the dates though. I sailed the regatta when Barry debuted that sail at Lake Cootharaba but did not sail the 1988 event. I did the Port Lincoln Nacra Nationals that year. Mmmmm we need to discuss over a beer soon. 

I'm  also not completely convinced by your enthusiasm for no boom on a DS for a classic. A foiler no problem. I'll go in to more detail when I'm a little less busy with other stuff. 

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5 hours ago, WetnWild said:

I'm  also not completely convinced by your enthusiasm for no boom on a DS for a classic. A foiler no problem. I'll go in to more detail when I'm a little less busy with other stuff. 

Wouldnt do DS on a Classic. 

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Funny, as stateside its starting to become proven that the DS is faster on the classics. The F18 class has also proven this.

In terms of boomless vs. boom, not sure why foiling or floating would change the arguments. I have used competitive sails and setups from each camps and prefer boomless myself as its less hassle and works just fine.

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3 hours ago, Sonofagun said:

Wouldnt do DS on a Classic. 

Interesting comment. I wouldn't do a current type of DS on a classic, because I think there is too little area high up. With the classic, you want it to heel while with a foiler, heel kills speed and stops foiling. I would be looking for a bigger head sail to the current DS's we are seeing, but would keep the DS because if it makes a significant difference on the F18's, which it does, it has to make a difference on the classic A.

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No question the DS works in the A for classics here.  We've had people sailing them for at least a year and winning races.  As one sailor said it, he had to buy one if he wanted to point like the foilers using them upwind.  The deck sweepers for classics that Jay Glaser and Randy Smyth have made are adapted to the needs of a classic.  Jay's are designed for a boom and Randy's are not as Randy was boomless as a philosophy as early as 2010 when I first started sailing the A-Class.  I had pics of Randy's handy so included them here.

Some older boomless rigs attached too, courtesy of a presentation Peter Block recently gave us at Lake Lanier.  He has been sailing the class since 1967.  Just terrific to have his experience and sharing of info. Check out the one with the large head and cut out leech.  

 

 

 

Smyth DS Classic1.JPG

unnamed-6.jpg

sellnau pics_32_0001.jpg

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