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#245972 - 03/22/12 05:46 PM Re: US Olympic Multihull Trials [Re: pitchpoledave]
waterbug_wpb Offline
Carpal Tunnel

Registered: 12/17/01
Posts: 3842
Loc: Naples, FL
Originally Posted By: pitchpoledave
But seriously C boards are a real step forward for cats.. My experience is that it makes a boat much easier to sail and lighter feeling especially at the limit.


Do these boards make the optimal performance window more or less narrow than straight boards? I think the answer to this question may dictate how well it does in the recreational marketplace.

FYI I consider "recreational marketplace" those of us who like performance sailing but don't have any realistic expectation of getting to the pro level...
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#245991 - 03/23/12 03:19 AM Re: US Olympic Multihull Trials [Re: waterbug_wpb]
pitchpoledave Offline
old hand

Registered: 06/12/02
Posts: 790
Loc: Toronto, Ontario
I don't know but I suspect it does widen the weight range because the boat doesn't displace as much..Maybe Mike Krantz can chime in on that.

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#246175 - 03/26/12 08:49 PM Re: US Olympic Multihull Trials [Re: pitchpoledave]
Wouter Offline
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Registered: 06/16/01
Posts: 9582
Loc: North-West Europe

I was foolish enough to place a posting about comparing the Nacra 17 to the Nacra F16 in the thread about the US multihull committee. Sorry about that.

This post did however receive some interesting replies and therefor I present a link that that thread here.

Nacra 17 to Nacra F16 comparisons

Wouter
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Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
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#246180 - 03/26/12 09:08 PM Full foiling a catamaran [Re: Wouter]
Wouter Offline
Carpal Tunnel

Registered: 06/16/01
Posts: 9582
Loc: North-West Europe
I was clearing out my archive of catamaran design topics and ran accross this paper. (BEWARE, it is a 13 MB download)

Paper on the non-foiling Alpha and foiling Rocker C-class cats when racing Patient lady 6 and Cogito

It is actually a good read and very insightful about foiling cats. I guess that this proofs Tim Bohans idea about lashing to Moths together and thus arrive at a full foiling cat with a leap in performance as outside of the realm of reality. Sorry Tim.

Basically the C-class contest tried to improve performance WITHIN a fixed rule base as indeed all the cats at the ISAD evaluation do. That Nacra 17 is pretty much a standard beach catamaran but fitted with partially lifting foils.

One of the more interesting questions is whether the Nacra 17 (or indeed nacra 20c) with curved foils is faster then the same designs with normal straight boards. Of course this question is not answered directlt by this paper, although both Cogito and Alpha used straight asymmetric daggers rather then curved foils as tried an earlier C-class competitor Patient lady ?? (I forgot which number this version had)

Most interesting fact in the paper was that Rocker proof just as competitive as Alpha ones the foils had been sawed off the boat. Auch ! That basically means that the performance of Rocker was actually held back by the lifting foils rather then being increased or stay the same.

I wonder what this says about (symmetrically) curved foiled cats. Afterall, Neither the Nacra 20C or the Nacra 17 has yet proven to perform beyond their Texel or ISAF handicap ratings. (i.e. Thai regatta and now the ISAF Olympic trials). Note that the Nacra 17 is rated the same as an F16 under SCHRS rating system (12 secs/hour quicker actually, but that is next to nothing)

Anyway, read the paper and make your own mind up.

Wouter



Edited by Wouter (03/26/12 09:19 PM)
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Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
The Netherlands

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#246181 - 03/26/12 09:10 PM Re: US Olympic Multihull Trials [Re: John Williams]
MarkMT Offline
old hand

Registered: 05/24/03
Posts: 1019
Loc: Lake Zurich, IL
Maybe this has been answered somewhere else already, but I'm curious about whether all the boats sailed with the requested two piece mast.

A comment on AHPC's Facebook page noted that they were sailing in standard Viper configuration, which might be taken to mean a one piece mast, though I suspect that isn't what they meant.
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http://crawsailing.org

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#246183 - 03/26/12 09:14 PM Re: US Olympic Multihull Trials [Re: MarkMT]
Wouter Offline
Carpal Tunnel

Registered: 06/16/01
Posts: 9582
Loc: North-West Europe
I only know that Darren Bundock admitted that he had ordered a two-piece carbon mast for the Viper as a measure to cover that base. Apparently, they decide not to use it on the trial boats (although there was a third Viper at the trials)

Maybe he brought one along, just in case, and mentioned it as an option in that panel discussion. Personally, I feel the two piece mast is a pointless requirement and it appears none of manufactorers are in favour of it even when they covered their bases as Darren did (nacra for example did)


Edited by Wouter (03/26/12 09:16 PM)
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Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
The Netherlands

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#246193 - 03/26/12 10:12 PM Re: US Olympic Multihull Trials [Re: Wouter]
Mark Schneider Offline
Carpal Tunnel

Registered: 06/17/01
Posts: 2687
Loc: Annapolis, MD
The dog that has not barked yet is the ISAF grade I schedule for the next cycle. We were told that they want to de emphasize Europe regattas as the path to a medal.. perhaps 2 grade I s in Europe. New qualification criteria.

So.. the need to box these boats up and ship to new continents and countries may be much greater in the future.

For instance... why is the America's Grade I ISAF event in Miami... given the games in Brazil... I would bet that ISAF moves those to a South American country....

The costs in shipping have probably been sorted out and presented in their presentations... BUT who knows... some factory teams reportedly showed up for a MIXED Trial with NO Women on their team... That's almost as good as the US sending a Mixed team to the MEN's ISAF World F18's championship.... (FAIL)

(What's so hard to understand about the word MIXED?)
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#246203 - 03/27/12 03:36 AM Re: Full foiling a catamaran [Re: Wouter]
samc99us Offline
addict

Registered: 03/06/09
Posts: 408
Loc: Solomon's Island, MD
Originally Posted By: Wouter
I was clearing out my archive of catamaran design topics and ran accross this paper. (BEWARE, it is a 13 MB download)

Paper on the non-foiling Alpha and foiling Rocker C-class cats when racing Patient lady 6 and Cogito

It is actually a good read and very insightful about foiling cats. I guess that this proofs Tim Bohans idea about lashing to Moths together and thus arrive at a full foiling cat with a leap in performance as outside of the realm of reality. Sorry Tim.

Basically the C-class contest tried to improve performance WITHIN a fixed rule base as indeed all the cats at the ISAD evaluation do. That Nacra 17 is pretty much a standard beach catamaran but fitted with partially lifting foils.

One of the more interesting questions is whether the Nacra 17 (or indeed nacra 20c) with curved foils is faster then the same designs with normal straight boards. Of course this question is not answered directlt by this paper, although both Cogito and Alpha used straight asymmetric daggers rather then curved foils as tried an earlier C-class competitor Patient lady ?? (I forgot which number this version had)

Most interesting fact in the paper was that Rocker proof just as competitive as Alpha ones the foils had been sawed off the boat. Auch ! That basically means that the performance of Rocker was actually held back by the lifting foils rather then being increased or stay the same.

I wonder what this says about (symmetrically) curved foiled cats. Afterall, Neither the Nacra 20C or the Nacra 17 has yet proven to perform beyond their Texel or ISAF handicap ratings. (i.e. Thai regatta and now the ISAF Olympic trials). Note that the Nacra 17 is rated the same as an F16 under SCHRS rating system (12 secs/hour quicker actually, but that is next to nothing)

Anyway, read the paper and make your own mind up.

Wouter



Nacra did extensive 2 boat testing during the F20c development and proved in-house that the curved foils were superior. Why else add an easy $1-$2K to the boat in a depressed economy? They are also here to stay in the A-Cat's. My general impression, from well outside both classes, is the curved foils aren't inherently faster upwind through beam reaching, but aren't slower on that point of sail. Downwind though they let the boat gybe through narrower angles, and if the sea state gets rough, make the boat easier to handle. There is still much to learn about there use and getting the maximum performance from a C-foil is more work than a straight board, that is inherent to the lifting nature of the design.

What I find interesting about these trials is the lack of Nacra F16 vs. Viper F16 data. Frankly, I don't believe a lick of information coming out of the event, it's all been spin doctored to death.


Edited by samc99us (03/27/12 03:37 AM)
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#246209 - 03/27/12 08:19 AM Re: Full foiling a catamaran [Re: Wouter]
Tony_F18 Offline
Pooh-Bah

Registered: 09/16/04
Posts: 2141
Loc: +31
Originally Posted By: Wouter

Neither the Nacra 20C or the Nacra 17 has yet proven to perform beyond their Texel or ISAF handicap ratings. (i.e. Thai regatta and now the ISAF Olympic trials). Note that the Nacra 17 is rated the same as an F16 under SCHRS rating system (12 secs/hour quicker actually, but that is next to nothing)

From what I hear the N20C's rating is quite soft so I'm not not too sure about that.
The N17 has not actually sailed any races yet but I would be surprised if it is slower then an F18, the foils might allow it to be pushed a bit harder in all conditions?

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#246210 - 03/27/12 08:33 AM Re: Full foiling a catamaran [Re: Tony_F18]
Wouter Offline
Carpal Tunnel

Registered: 06/16/01
Posts: 9582
Loc: North-West Europe
of course, this is all subject to further on the water data.

However, what I find interesting about this article as a designer is the following conclusion.

Something that works so well in the moth doesn't work at all in C-class.

I mean we do similar reasoning all the time right. This and that works in the A-cats so it must also work for design X. Well, it appears that more often then not you can not transfer aspects of one design to another like that.

Another example, A wingsailobviously works in the C-class but doesn't in the A-cats. We saw that again a few years ago.

This article reminded me again of how easy it is to draw conclusions that will not hold up under proper testing or real life.


Edited by Wouter (03/27/12 08:42 AM)
_________________________
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Formula 16 NED 243 (one-off; homebuild)
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