Evolvement of foiling sailboats over the last 70 years

Angel, the same basic type of "C" foil setup I described on the early Orma's was recently approved for the Multi50-no rudder T-foils allowed. So they have to be sailed
carefully when really pushing hard.....
Multi50 examining minimum weight and lifting foils https://www.boatdesign.net/threads/multi50-examining-minimum-weight-and-lifting-foils.55017/page-2
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A friend has a 450 SL now and has had it since around 1979. Expensive repairs but not needed often....

 

Thanks Doug for explaining the use and speed gain of vertical lift foils for non total lifting !

 

You're welcome!

 

Yes, Doug, I realise that a heavy cruising cat or Winnebargo is not like an ORMA 60 or F1 car. They are different and therefore giving them the same set of foils is silly. That was my point!

 

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They would-obviously-NOT be the same set of foils! All "C" foils are not designed alike..........

 

I would assume Catana has tested the speed gain of vertical lifting force generating C foils vs lower drag vertical straight boards, so I would like to see the results of that, but in the below vids downwind they don't employ the C foils to generate some vertical lift . . .

‘‘ . . . curved foil-type daggerboards to help avoid the risk of “tripping up” and to optimise the pointing angle . . . ’’ no speed gain or vertical lifting claims there.

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(click pic to enlarge, click again to shrink)​

 

I didn't read or hear any comments ? One things for sure: a fully deployed curved foil is likely to produce some vertical lift. But they don't seem to fully deploy the foils?
I can't think of a single reason to use curved foils except to generate vertical lift. Somewhere I have the original info-I'll try to find it.
Less chance of "tripping up"(pitchpole?) if the foil or foils are lifting the front of the boat.

 

Post #1 here: Curved Lifting Foils on Cruising Cats?? https://www.boatdesign.net/threads/curved-lifting-foils-on-cruising-cats.39585/#post-484826
From post 17:
All this has culminated in the new Catana 59. A Catana with incredibly streamlined hulls, classically elegant, and offering astounding performance. The sail plan is borrowed from racing vessels, with a short mainsail that is easy to manage and a larger foresail. Moving away from the legendary daggerboards that made the Catana shipyard's name, this catamaran is fitted with revolutionary curved daggerboards, to create a hydrofoil effect. The result is an extremely safe and comfortable boat that achieves astonishing acceleration and an extraordinary cruising speed.

 

I don't know about that. The 62' cat is rated at 19.2t light, so fully fuelled, packed with people and supplies (it has accommodation for 6) it's probably well over 22 or 23 tons. That's 3 times the weight of an AC75 ready to sail with crew and guest racer on board.

The C foils are likely about as effective boost in performance as the diffusers you see on street sports cars to lower drag. Yes, they help in theory and maybe in certain circumstances they make a tiny difference. If someone with a Catana 62 really wanted to go fast it would make a vastly bigger difference to take weight out of the boat (or just buy something that actually does go fast).

 

The Evolution of Foiling Sailboats: there is an interesting race going on in the RORC Caribbean 600. Part of the story is about two of the nearly identical MOD 70's starting 2 hours behind the whole fleet to give the MOD 70 Argo more time to get ready after just capsizing 48 hours ago. The MOCRA multihull fleet would not agree to delay the start, so Giovanni Soldini(owner and Skipper of Maserati) agreed to start late to be able to race Argo and the Race Committee agreed that the two MOD 70's could have their own "class" and a delayed separate start. The fact that some of the MOCRA boats would not agree to a 2 hr later start hurt ARGO most because now she won't be scored under the MOCRA Handicap System.
Well,it is so very cool that just a few minutes ago when I checked, Maserati and Argo lead the whole fleet including ALL the MOCRA multihulls and two hot shot multies "Fujin"(a Bieker design) and the DNA F4 "Falcon"(the only other full flying multi in the fleet besides Maserati).
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The other part of the story concerns some recently published comments in this thread about beachcat foilers only gaining around 4% more speed over their seahugging sisters. That comment was not reflective of the real world of foilers and foil assist but was assumed to be by one poster.
So today, I checked the speed of the MOD 70 multies upwind and downwind. But first a bit of a qualifier: Argo is a standard MOD 70 and as such uses two "C" foils(one on each ama) that provide vertical lift resulting in greater speed than if she was not using them. Maserati is a full flying trimaran using a revolutionary foil system designed by Guillaume Verdier(and very similar to the Fire Arrow Foil System designed years earlier than the Maserati system). Maserati was the first fullsize trimaran to use this system:

Upwind Maserati was 6.9 % faster than Argo,
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Downwind Maserati was 11.1% faster.
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Keep in mind these percentages would be even greater if Argo had not been using foil assist.
Because Maserati is a full flying foiler, she is also heavier than Argo.
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Stunning Fleet for RORC Caribbean 600 Feb 18,2019 https://www.boatdesign.net/threads/stunning-fleet-for-rorc-caribbean-600-feb-18-2019.61583/#post-848496

 

You really should reference what you are referring to (presumably CT249 in post 101) rather than casting aspersions. What CT249 posted was analysis of race results for small or off–the–beach cats and therefore absolutely is reflective of actual performance, unless you can prove either his data or analysis flawed (which you have not). To say it's not reflective of real world performance with zero evidence is plain wrong.

The fact that two MOD 70s, which are to beach cats as an AC50 is to a Hobbie 14, have a particular speed differential does not invalidate CT249s analysis in the slightest. It's one result from entirely different boats. Your claim that it counters CT249s conclusions also ignores any effect from Argo's capsize and subsequent rush to prepare for the race that may have affected its performance.

The VMG difference* was 21.4kn (Maserati) vs 20.9kn for Argo, an overall difference of 0.5kn making Maserati 2.4% faster than Argo over the race. In terms of time difference, it was 38 min after 1 day 4 hrs of racing, again less than 3% difference. And Argo sailed 10nm further.

So 4% difference is actually over stated.

* Based on provisional results posted at 2019 Fleet Tracking | Tracking - Players | Race Information http://caribbean600.rorc.org/Tracking-Players/2019-fleet-tracking.html

 

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No its not-only of catamarans using a particular rating system and where many don't foil a significant portion of the time(upwind) --not representative of all foilers and foil assist at all. It presented a false impression of the real world of foilers and foil assist.
What I said was: "That comment was not reflective of the real world of foilers and foil assist ..."
The MOD 70 comparisons are among the best and most relevant I've seen yet and much more realistic considering "all foilers and foil assist".

 

Given that this entire thread was started as a result of a previous thread being locked for incivility we should be careful about being too robust in our rebuttals of other people's comments.

That said, I think Doug that you are missing the point of CT249's post (#89). He specifically addressed the point that the larger gains seen in the ACs (and potentially in the MOD70s) do not appear to be passed down to the foiling vessels that are available to average sailors. He then gave an example of a large data set of boats of this type, making no aspersions that the data could be extrapolated to "all foilers and foil assist".

OTOH I think CT249 that you were rather unfair in attacking Doug Lord for comparing ORMA60s to cruising cats. I believe he was answering Angelique's question about the benefits of partial lift in good faith (see post #119):

 

That is what I quoted, verbatim, with context, and replied to.

A comparison that shows the speed difference between Maserati and Argo over a race of about 1 day 4 hours was less than the 4% calculated by CT249 based on results from beach cat races. The two results likely fall within the error margin of each other.

I think you just agreed with CT249s analysis.

 

I didn't say it was "representative of all foilers" so don't imply that I did. However, no reasonable person can deny that the SCHRS data is reflective of much more data than you have available on the question of the comparative speed advantage of foiling cats, albeit small ones which I clearly stated. It is representative of what is almost certainly the largest database of small foiling cats.

The Texel system, created for the world's biggest cat race, rates the flying A as just 1% faster than a straight- or C-boarded A Class. The fully foiling NAcra 20 FCS is rated at 86, compared to the 89 of the standard Nacra 20C.

The Australian yardstick rates A Class full foilers as less than 3% faster than the C-foil "Classics", and it's pretty much the same with the Nacra 17 and 15. The yardsticks may not be perfect but they come from someone who, unlike Doug, actually sails high performance cats and has a database of race results provided by clubs.

We therefore have three systems that say the same thing. We can either believe data-driven information from champion sailors, including a leading foiling cat sailor, which have access to a huge amount of data, or we can believe one guy who has never sailed a foiling cat, never won a championship of significance, may never have even seen one, and pretty much just Googles stuff.

If the current small beach foilers don't foil upwind then it may just show how hard it is to achieve that aim. And finally, as Fred has noted, the Caribbean race, for example, showed a smaller advantage to the foiler.