35th Americas Cup: Foiling Multihulls!

There are two explanations I can think of (not mutually exclusive):
1) The wing sail is a fixed design which all teams must use. It could be that the bottom area of this wing sail is underloaded relative to the optimum loading distribution, and the jib makes up for that.
2) The flow in the corner between the wing sail and the deck will separate more easily than the rest of the wing. The jib will suppress this separation to some extent. A solid slat could probably do this better, but to work on both sides it would have to have reversible camber which would be a mechanical nighmare.

 

We have differing viewpoints.The AC was never,and probably never will be,a popular sporting contest.It is a contest between big egos and big bank balances.The rest of us can watch if we feel so inclined or ignore it.Just as I ignore the Tour de France.

I find keelboat racing dull and having watched televised AC's I prefer the foiling cats.The course format is unlike any we are likely to encounter elsewhere and in this respect it matches the boats.As to keelboats being the most popular form of racing,they certainly are in some locations.Yet when I see a cloud of sails they are seldom keelboats and it is surprising how widespread catamarans have become.Here in England almost every pond features a sailing club and while they may not have the numbers of the boom years of the sixties and seventies,they are almost exclusively centreboard dinghy orientated.On the other hand,the Solent is full of keelboats with few people spectating.That changed last weekend when the AC competition took place and hundreds of thousands were watching.

In the final analysis the AC will endure as long as there are people willing to issue a challenge to the holder.They can decide what type of boat they prefer and designers,boatbuilders and sailmakers will get some work.The mercenaries that operate the boats will make a good living too.

 

Why is it nutty? For any boat size/weight/class, there is always a wind speed below which displacement is faster than foiling. This may have been the case on the day in the video, in which case they were doing the right thing to win.

And regardless... acquiring the ability to foil in light air as a minimum requires a new set of larger foils and hence more $$$. Might not make sense given finite campaign resources.

 

Light Air Foiling

It's nutty because the people have come to see foiling-not seahugging. I'm sure there is a cost to the repeated episodes of non-foiling we have seen in this ACWS especially in public interest. Whether that cost is greater than the cost of foiling in 5 knots and up is a good question. My gut feeling is that increasing the frequency of foiling and showing that the boats can be designed and built to foil throughout the wind range would pay off handsomely.

 

I think the decline in new sailors has more to do with the WORLD's economy that has decimated the boating industry since 2008 and even before that.

Plus the decline in free-time that many people use to have prior to there having to really buckle down to work to make a living for their families.

I don't think it has anything to do (or very little) with the foiling aspects of the multihulls in the America's Cup.

I also find it interesting, and applaud their decision to go with the smaller cats (more affordable, more inclusive) rather than those huge 72 footers. Perhaps we will see more countries able to participate.

 

I think it has more to do with the overall capabilities of vessel to meet the variety of conditions it might encounter (such as help with tacking at low displacement speeds, and maybe some reaching situations, etc).

One of my purposes in posting that original inquiry was to make a distinction about what kind of sailing rig one might end up with depending on whether it was being designed by an aircraft guy or a sailor. The aircraft guy might just say the pure wing is the most efficient. The sailor might say we need something more,...like a headsail.

BTW, that same question has sparked some real good discussions,...and a few video presentations over here:
http://www.cruisersforum.com/forums/f48/why-jibs-on-america-s-cup-catamarans-170061.html

 

Oh, I'm quite happy having different viewpoints - it's just that I was trying to explain why some of us criticise the current setup.

Yes, dinghies are more popular in the UK, but not in places like Australia (where it's 2:1 yachties) and America (where it's even more tilted towards the big boats) or much of Europe.

Looking at UK multihull numbers in comparison with their fleets back in the '60s and '80s doesn't actually show much growth, incidentally.

 

Surely people in a sport can have their say if they think an event is harming the sport? Do you reckon football players should just be silent about the issues within FIFA? Should we all just ignore the problems with the IOC unless we run an Opposition Olympics?

I don't need to be told to do it, thanks - I have already done a fair bit for the sport, which is (for example) why I'm only of only five people to have been elected as a life member by my class association.

 

When it comes to the America's Cup, I don't see the need to be so negative about it. They've put on one of the most spectacular competitions in the history of sport, taking it a long way from the borefest that it used to be, and they're generating interest in sailing by making it supercool. Your criticism of these foiling AC boats comes across as a call to shut them down, and that's like asking F1 and Indycar racing to pack it in. There is plenty of room for diversity and that diversity is not harmful. If something is dull, it won't attract an audience and it will disappear all by itself.

I'm just suggesting that positivity is a better road to take than negativity and that negativity is harmful to the sport, not least because it's depressing. If you don't like something, instead of trying to tear it down, why not build something new to compete against it and bring about change in a constructive way that adds to the sport instead of telling other people to get off the water? I think there's room in sailing for something like the Davis Cup in tennis, taking a sport in the form that ordinary people actually play it and turning it into a team competition between countries where wins for individuals are not directly rewarded with prizes and everything depends instead on the performance of the team as a whole. If you don't want it to be named after you, that's fine. With ideas of this kind it takes someone with vision to get things going, so maybe I should pitch it to Ben.

 

There is no doubt in my mind that going to multihulls was a step forward for the AC. I liked the old boats but these are better.

For me the main problem in creating excitement has more to do with the filming than anything else.

For example the excitement at the start is better promoted by placing a "fixed" camera (drone?) on the starting line during the last 2 minutes, than switching back and forth between different shots from the various boats.

In F1 the start is always projected with a fixed camera pointing at the oncoming cars. Even here i think a drone view would bring out the tactics at the start better.

As in F1, by all means do project onboard shots from the individual boats but only in replay.

The director of the camera room (or whatever he's called) needs to be a racing sailor or at least needs to understand what makes sailboat racing exciting for us.

 

David, your view that the AC was "a borefest" seems to be at least as negative than anything I wrote. Why is it OK to call one type a "borefest" but not OK to express concerns based on research about another type?

The fact that the AC is claimed to be making sailing look supercool misses the point that objectively applying the results of independent analysis of the perceptions of sailing shows us that it may actually be hurting the sport. Why should we be censored from talking about applying the lessons of the studies that sailing paid for?

F1 and Indycar are great examples of the effect of high-profile events on a sport - motor racing receives enormous support from the world's biggest industry and yet it has comparatively few participants, ranking only about 30-40th most popular sport in English speaking countries. They demonstrate that creating interest often does not help the sport, something also demonstrated by the work of people like sports economist Wladimir Andreff and others - so why can't we point to those facts when it comes to sailing?

The funny thing is that we still haven't seen objective data to show us that the current AC is working. No one has presented (say) national championship attendance figures or class membership numbers and shown an upward spike. No one has shown objective data demonstrating a surge in multihull sailing. No one has shown how the overall sponsorship from independent sources has grown. If it's working, why not just prove it?

We already have a "Davis Cup" event, in the form of the Olympics and ISAF's World Cup. I have already played a (very, very minor) part in the selection of classes for the Games as part of a committee member of an international class and president of a national class. I've done enough to allow me to express my views, and there is no way I'd set up an opposition series to the Olympics.

By the way, it's hard to see why the concept of a televised multihull short-circuit pro event should be seen as something that took vision - it's basically a reproduction of a concept from the mid 1980s (ie Formula 40, Prosail), and similar things had been done in other disciplines before that. With respect, it doesn't take a massive amount of "vision" to do in 2016 what some were doing in 1980. Been there, done that, seen it shatter a popular part of the sport to pieces.....

By the way, I stayed out of the thread for some time, until someone asked a direct question and I answered it. I didn't leap in just to be negative.

 

The video efforts at the current racing events, and the racing the last time in San Fran goes FAR BEYOND those efforts of 1980. Look it up.

 

35th America's Cup on Foils!

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Just out of curiosity what "direct question" were you answering in the above post 487?

 

AC Trickle Down

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The UptiP foils invented by TNZ have trickled down to numerous foiling catamarans including C Class cats and the principles behind them have even been incorporated into 60' foil assist monohull "Dali" foils.
They have trickled down to at least one 19' trimaran design* and to one 60' modified MOD 70.
They have trickled up from the TNZ AC72 to the 100' Macif trimaran and will likely be used on the new Gitana 100 foot tri as well.
* and to one 65" Test Model which was the first trimaran of any size to use UptiP ama foils......
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I would guess that the "trickle" down from AC 34, in terms of the dollar value of the boats that have benefited from the revolutionary technology developed there, exceeds the "trickle down" from any other AC in history.

 

The wingsail on the trimaran USA17 was designed to be used without a jib in light winds. Sailing experience showed there was a crossover wind speed, below which it was faster to have a jib than to sail without a jib. In general, the boat performed better when sailed more up-range from its targets. I think other wing rigs are similar, in that it takes actual sailing experience to assess the value of a jib with the wing.

Jibs do help with maneuverability, as several people have pointed out. They make it possible to adjust the sail area for different wind speeds. They also fill out the bottom of the spanwise lift distribution in a way that is lighter than simply adding chord to the wingsail.

I don't think the jib plays much of a role in suppressing separation. The leading edges of most wingsails are far from separation, even under high lift conditions, and the leech of the jib is not close enough to interact strongly with the wing leading edge.

The jib does play a role in changing the local apparent wind angle, reducing the angle of attack that the lower wing sections see. At the same time, the jib sees an increase in angle of attack due to the wash from wing lift.

Arthur Rothrock built a landyacht that had a wingsail with a slat. The slat was attached with a four-bar linkage that allowed it to flop freely from one side to the other, and still be positioned favorably for each tack with an overlap of the wing leading edge. Mechanically, it was more complex than a simple hinged flap, but a lot less complex than a Handley Page slat with tracks and rollers. It was successful in so far as the slat behaved as intended. However, I don't think it added significantly (if any) to the speed of the boat because leading edge stall is not really an issue for those craft.