Open 60 using curved lifting foils

[Doug Lord]

Just launched in 2010, Virbac-Paprec 3 is the first Open 60 that I've seen* that uses curved lifting foils-like the 60' tris do and most of the g-class tri's do. It will be interesting to see if this design advance pays off as the boat is tuned up. Lifting foils on fast monohulls for "foil assist" are the wave of the future.....
* there may be others that I haven't found yet..
--Foncia uses angled boards-angled the opposite way of most Open 60's specifically so they can develop lift.

[Doug Lord]

These guys with Vincent Laurent Prevost(on Virbac-Paprec) are pioneering lifting foils on Open 60's . They have designed: Foncia , PRB, Group Bel and Virbac-Paprec 3. This is trully pioneering work with lifting hydrofoils on fast keelboats! And very exciting stuff.

Here is the rationale for the angled(opposite of most older 60's)foils on Foncia:

"Also under the heading of evolution is the big inward curve of the daggerboards which enables the boat to be slightly lifted, in the same way as foils, but without the disadvantages of heavily curved daggerboards."
http://sailracewin.blogspot.com/2010...its-water.html

Both boats have lifting foils-Foncia angled straight, Virbac-Paprec 3 curved:

[Doug Lord]

Similar to the boards on Foncia.....Third boat I know of using lifting foils:

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An unconfirmed rumor(so far) that Saffron, designed by Verdier/VPLP used curved lifting foils in the last Vendee. Amazing if true-why has this story been so quiet??
--I just confirmed on the Vendee site under "pictures" that PRB used curved foils in the last Vendee!
--From the Vendee site about Saffron(also reflects the thinking on Virbac 3) :
Appendages: The most unusually-shaped daggerboards are found on Safran — the design team of Marc van Peteghem and Vincent Lauriot-Prévost, in association with Guillaume Verdier, have been inspired by the curved foils on ocean racing trimarans. The aim is to reduce the space taken up on deck when the daggerboards are raised, and give added lift. http://www.vendeeglobe.org/en/news/5...-envelope.htmlle:

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From Sails and Sailboats-roughly translated by google:
On sailing canting keel, fins are usually inclined outwards so that the drift downwind approaches the vertical when the boat heels. On Foncia , this inclination was reversed (it is 9 °), so that the wing is even more lying in the water, and plays a supporting role, relieving the bow and facilitating the planning.
"Our monohulls now have speed close to polar multihulls for years 85-90, precisely the time we started to equip them with foils" says Mich'Desj '.

http://www.voilesetvoiliers.com/cour...bord-de-foncia

[Doug Lord]

Best picture yet of the retractable curved lifting foils on V3-the leader in the BWR and the only boat using these foils. Two other boats(one retired) use angled lifting foils-not quite as effective in vertical lift as these:


(click on image twice for best detail)

[MechaNik]

Very cool!! Now these boats will be sailing in a variety of conditions and I suppose at different speeds. How do they adapt the foils to perform well at different speeds, because I thought a foil had a very limited effective speed range?
I would like to learn more about how foils are applied to pleasure boats, any sources for some good reading that is not soaked in physics?

[Doug Lord]

Originally Posted by MechaNik

Very cool!! Now these boats will be sailing in a variety of conditions and I suppose at different speeds. How do they adapt the foils to perform well at different speeds, because I thought a foil had a very limited effective speed range?I would like to learn more about how foils are applied to pleasure boats, any sources for some good reading that is not soaked in physics?

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That's one of the beauties of curved lifting foils: they can be optimized for the conditions better than, say, T-foils or fixed surface piercing foils since as they are retracted the portion of the foil developing lift diminishes and so does wetted surface. From a design perspective, the radius of the curve can be specifically targeted to the type of boat the foil will be used on allowing the amount of vertical and horizontal lift can therefore be optimized for the specific characteristics of the boat.
--
The best book I know of on practical hydrofoils is Ray Vellinga's "Hydrofoils Design Build Fly" by Peacock Hill Publishing and available on Amazon,
ISBN: 9780982236116 . The book covers sail and power hydrofoils including the Moth and is well written in a style that interweaves theory and practical building advice in a very readable and understandable style.
Here in the "Sailboats" forum you might check out "Foiler Design", "New High Performance Multifoilers", "Peoples Foiler 2010" and a few others like "Speed
Dream"(Murnikov), "60+or-20' foiler", "Mirabaud", "Moth on Foils", "Dinghy Design: Open 60 Influence" and a few others here and under "Multihulls".
Hope this helps....

[Doug Lord]

The first monohull keelboat to use curved lifting foils to WIN a round the world race-leading almost the whole way. Congratulations to the Team-Peyron, Dick and Verdier/VPLP!
Mapfre, soon to be second place also uses straight angled foils designed to create some vertical lift.
Together these boats represent a major leap forward for ocean racer design!

[Doug Lord]

I am convinced that the curved lifting foil technology is a milestone in sailboat design-first used by Saffron(3rd place) in the 2009 Vendee and now in only the second round the world race the technology has been used in: first place!
I think this type of foil can be applied to any type of monohull from dinghies to super maxi's with tremendous benefits. The design of the foils can be varied so much that lifting or lateral resistance can be given priority and the adjustment available is just phenomenal-allowing all the vertical lift to be eliminated leaving just lateral resistance or anywhere in between.
There is a lot more to come from this technology!

Almost day by day account of the 2011 Barcelona World Race won by V3: Barcelona World Race/ Open 60's


Also see this thread: Dinghy Design: Open 60 influence?

[Doug Lord]

For future reference, in September 2010 IMOCA, the class association for Open 60's approved the use of Hugh Welborn's DSS system on Open 60's.
This could be very interesting in combination with(or without!) curved lifting foils.......

Dynamic Stability Systems-IMOCA approves!

[mitchel]

SAFRAN (Marc Guillemot) was the first boat with curved foil I think.

I think curved foil are really benefic with multihull beacause they are light and curved foil bring lifting force.

With heavy monohull (because of keel) lifting force is less efficient.

[Doug Lord]

Originally Posted by mitchel

SAFRAN (Marc Guillemot) was the first boat with curved foil I think.I think curved foil are really benefic with multihull beacause they are light and curved foil bring lifting force.

With heavy monohull (because of keel) lifting force is less efficient.

Thanks, Mitchel! Right-more in post #3. The trimarans that first used curved lifting foils had a single curved foil support up to 70% of the boats weight. Haven't got a reliable figure on the Open 60's but it surely is less than that.
Curved foils used in dinghy design could easily lift high percentages of the dinghies weight-way more than the current 15% lifted by the rudder t-foil on an I-14.
Foil assist from DSS to curved lifting foils is an exciting new design application for lifting foils in monohull keelboat and dinghy design.

[Doug Lord]

Virbac-Paprec 3 resoundingly won the Transat Jacques-Vabre 2011 from France to Costa Rica leading almost the whole way and finnishing over a hundred miles in front. Was it the curved foils? Not alone but they sure played a role... Congratulations to V3!
See thread in "multihulls"...