Foil Assist Monohulls

IMOCA 60 "Charal" launched: Pressure Drop - The New Charal Launches http://www.pressure-drop.us/forums/content.php?8547-The-New-Charal-Launches
>My impression is that there is a much greater emphasis on vertical lift on this particular foil design.
-------------------
Accueil - Jérémie Beyou http://www.jeremiebeyou.com/

Construction de bateaux et pièces industrielles en composites https://www.cdk-technologies.com/

-------------------
pix by Yvan Zedda:

 

I have noted this good result because Malizia 2 (ex Gitana) had not showed up to now its full potential, being obliged to abandon in the last Vendée Globe at mid race when she was third not far from the 2 leaders. And also because the skipper is a German sailor Boris Herrmann who seriously prepares the next Vendée Globe 2020, it is good for the international dimension of this race.
I agree that it is not easy anyway to compare the performance of two boats of which design purpose are quite different :
- on one side Malizia 2 , 18,28 m x 5,70 m , an Imoca oriented to single-handling (they were 5 on board for the above race) and Vendée Globe sailing conditions, within the Imoca 60 rules which involve restrictions :
Imoca - Malizia (MON 10) https://www.imoca.org/en/boats/40-mon-10-malizia.htm
- on the other side Varuna VI, 17,07 m x 4,95 m, a Ker 56 "no compromise" design oriented to perform both in inshore races and in long distance offshore races, with 14 berths accomodation meaning that such numerous crew play an important role to permanently hard sail the boat as to bring an extra righting moment :
Knierim Yachtbau - VARUNA VI – Ker 56 Racer http://www.knierim-yachtbau.de/index.php/en/new-build/launched-projects/varuna-vi-ker-56-racer/103-varuna-vi-ker-56-racer-en
The potential of these two designs are probably very similar at the end, and the lenght parameter plays a role mostly by medium winds : by light winds, it is the ratio sail/wetted surfaces, by strong winds it is the ability to go surf and to sustain sail surface (so then RM plays the major role) . At the question "how the foils made the difference" for this race, it is hazardous to answer.

I followed day-to-day the last Vendée-Globe, especially the first 3 weeks when the fleet , sailors abilities and sailing conditions were homogen for a comparison : below boat speed 18 knts, no difference, from 18 knts (i.e. Froude (Lwl) = 0,7) a slight advantage was visible for the foilers, up to 50 NM per day when the boat average speeds were 22 knts, i.e. about 2 knots more.
Since, other Imoca races clearly show that for light winds under 12 knots, the non foilers keep a net advantage.
Less intuitive is the performance of the foilers when upwind : it seems that they perform quite well and like a non foiler, Banque populaire VIII won the North Atlantic Bakerly 2016 race at an average speed of 12.91 knots (Froude 0,5 !) , 2 h 21 mn before non foiler PRB second :
The Transat: Armel Le Cleac’h wins IMOCA 60 class >> Scuttlebutt Sailing News https://www.sailingscuttlebutt.com/2016/05/14/transat-armel-le-cleach-wins-imoca-60-class/

The best comparison we can do for foil-assist / non foil-assist issue is to compare the foil-assist version with the exact same boat without foils and where the weight of the foils + corresponding hull reinforcements are put as lead in the bulb of the keel. I am doing this tentative with an home-made VPP for a simili Figaro III with and without foils, also extending the comparison with a simili Melges 32 with 8 crew and or with 2 crew, I will soon posted the results in the Figaro III thread.

 

Interesting photos, Hugo Boss look for the hull ! , and effectively quite large span foils.
To note that this new design is a VPLP one, no longer a Verdier one as they are now working on their own for the new Imocas. Here an old interview of Jeremy Beyou (April 2017) but interesting on his choices :
https://www.ouest-france.fr/vendee-...veau-sponsor-charal-et-un-bateau-neuf-4936357

 

Beyou:
"There is no more uncertainty about the need for foils. And now we will design the boats around the foils. The power of the boats will be less brought by the hull and more by the foils. They will therefore probably be narrower and have larger foils. We also hope that the rule that prevented the adjustment of the impact of the foils (trim adjustments) will be lifted at the next GA Imoca. This would be good news because it would improve the performance of the foils and economically it would be cheaper. Instead of making two or three pairs of foils, it would be enough to change the settings to try them. It will probably be a boat that will not look like the ones that already exist. And then we are two and a half years behind to make reliable and develop."

 

More I-14 Worlds on San Fran Bay(Richmond Yacht Club)-where the FOIL really assisted!!
A1847 - International 14 World Champs 2018 - Day Five - Race Four from VR Sport Media on Vimeo https://player.vimeo.com/video/285938457?color=c6026e

 

About Charal again, this interview of Jeremy Beyou in English the launch day :
News - Charal Ready to Take Flight - Vendée Globe https://www.vendeeglobe.org/en/news/19356/charal-ready-to-take-flight

 

Charal: what a foil!
pix by Yvan Zedda-


pix from catsailingnews by Yvan Zedda:

 

Foil Assist at speed!

 

Thanks very much for that excellent, objective and informed analysis!

Was the Bakerly race sailed in strong winds? I imagine it must have been, if the boats went that fast in a windward race.

 

Great boats, but it's sad to see that there are now only one-quarter as many 14s being built as there were before they adopted foiled rudders.

 

I don't intend to get involved in an extended argument, but your post immediately reminded me of the saying "Correlation does not imply causation."

 

I'm with Doug H on this one. Dwindling numbers is a phenomenon common to all skiff classes as far as I can see, not just I14s. So I can't see that as a factor.

Seeing a hydrofoiling fanboi use them as an example of the "foiling revolution" is tiresome though.

 

You're both right. Arguably, though, there is a huge lesson because before we had "the foiling revolution" we had a much-hyped "skiff revolution", where people like sailing writers and the European head of ISAF were saying that "skiffs were the future". The fact that, as you say, the skiff classes are dwindling is a lesson in how far people can go wrong when they predict that high speed sailing will become more popular.

Certainly some of the most influential sailors down here said that 14s suffered as a result of the extra expense of the T foils and the fact that when they were adopted, new hull designs followed, but the other skiff classes aren't doing very well either.

Many of us grew up in a culture where fast dinghies and skiffs were the standard high-performance sailcraft. There were cats, of course, but even the good cats tended to be a bit clunky in light winds, and yachts were heavy and pretty slow. These days, even a foiling dinghy looks slow compared to a kitefoiler and boats like TP52s seem to be really quick compared to something like an 18 or FD. Perhaps the dinghies and skiffs have now been eclipsed as high performance craft, in absolute terms?

 

International 14--- I wrote to Paul Bieker about CT's comment-this was his response:

Hi Doug,
There is no doubt that the foil made the boats more expensive and a bit harder to handle logistically. That said, they also made the boats significantly faster and easier to sail. I’d hesitate to pin the reduction in new build numbers purely on the hydrofoils. There are bigger trends at work – namely the reduced amount of discretionary income and time that the average person has and the increased cost of building boats in general.

All the best,

Paul

 

International 14--I also wrote to Ovington Boats and Nathan Batchelor sent this:

Hi Doug,
You are best contacting the class association who keep the record of boats built. The market has changed a lot in the last 15-18 years since T-foils came in – less double handed sailing especially in those classes requiring 2 experienced sailors.

Kind regards,
Nathan
==============================
I wrote to the US Class Association-no response so far....