NACRA 20 with Lifting Foils!

[Doug Lord]

First production "beachcat" with "foil assist" using curved daggerboards(banana boards)-very interesting. Stealth 16 (I think) was first or second in using rudder t-foils.

http://www.nacra.ca/images/stories/images/finalsmall.jpg

Press Release - 16-10-2009 – for immediate release

Nacra is proud to announce the upcoming launch of its new flagship, the NACRA F20 Carbon. This latest addition to the Nacra range is a new high performance 20 ft catamaran.

Peter Vink, head of the development team: “ The whole development team is very proud to share the first information about the new Nacra F20 Carbon. We have been working with the best-of-the best in the maritime industry to ensure that this is truly a “king of the beach” boat. It will be bigger, wider and faster than anything in-or outside its class”. Although nicknamed “Babyzilla” by the team, it will still be a boat that can be sailed by the local club racer and be able to win at it’s first outing at the club race.

Peter Vink:”We took all the best features and characteristics of our current F18 Infusion, which has won the last two F18 Worlds, and applied it to the new boat, as an example: the rudder system, mast extrusion, beams and some other small bits and pieces, this way we have proven technology on the new F20 Carbon”.

The development was done by world renowned designers, Morrelli & Melvin for hulls, Nils Bunkenburg, A cat guru for the foils, Performance Sails for the rig & sails combined with the in-house knowledge at Nacra.

Development and testing has been underway for over 18 months, 2 boats were fitted with both straight daggers and with foils to allow the team to compare; a third boat, a Nacra 20 was fitted with the wide beams and the new rig. The 3 test platforms allowed the development team to test in the real world without revealing to much about this new boat, so they could adjust and fine-tune the design.

A variety in masts, mast hardware positioning and different sail cloth and shapes has been tested. The new hull shape which has been created, starting with a wave piercing bow forming a diamond shape hull stretching backwards into a “square-ish” transom, is of mayor importance due to the combination with the curved daggerboard. Although the basic shape was chosen, several adjustments were made driven by new technology [computer fluid dynamics] and knowledge which was gathered by Melvin & Morrelli while working on the Americas Cup project for BMW ORACLE.

Pete Melvin:”It is not a coincidence that the hull shape of the new F20 Carbon shows resemblance with the floats of the AC boat, we were able to take the knowledge we gained at the AC project and scale it down to the F20 Carbon. The most noticeable and distinctive feature is the chine that runs from the bow backwards on the hull allowing the water to flow away from the hull. Combining the chine and wave piercing bow with the upper deck shape reduces drag piercing through the waves both upwards and downwards”.

Regular production will start any moment and the first boats will be ready to be delivered to the customers in the first months of 2010.
Please see attached document for technical data

[TTS]

Doug,

The Marstrom M20 has been built on a production basis for over a year with c-foils.

[Doug Lord]

Thanks, Tom. I just checked the Marstrom site and (unless I missed it somehow) none of the M20 pictures show curved boards nor is there anything written about it. Do you have a link?

http://www.marstrom.com/index.php?option=com_content&view=article&id=109:marstrom-m-20-gallery&catid=42:m-20&Itemid=67


Just found this: http://www.johncaseyworldwide.com/?p=975

[TTS]

I will look for the link. Some of the original M20's have been retrofitted and I think the c-boards might still be an option when being built. Marstrom makes them for the A-Cat as well. You also have Scheuerer out of Switzerland placing them on the G5. I think that they are also available for the 20 Beaver. ASG is offering them on the latest generation MKII Flyer.

[Doug Lord]

Thanks,Tom...

[Doug Lord]

Here is a rendering from Morelli and Melvin showing the curved foils:

[Sly]

What are the handling characteristics and benefits with curved foils on these boats?

[Doug Lord]

Your best bet is to ask Nacra. There could be a slight reduction in wetted surface and a slight increase in pitch resistance. There could also be a slight reduction in RM since the center of lift of the foil is inboard of the CB of the hull when the windward hull is flying and the windward board retracted.
Curved foils on 60' ORMA tris lift as much as 60% of the total weight -or more- significantly reducing wetted surface of the lee hull(ama) when the other two are flying. These foils, however, do not appear to have the capability of lifting anywhere near as much of the total weight.

[Doug Lord]

Good pix:

(click on image then again)

[DiasDePlaya]

http://1.bp.blogspot.com/_JCmc-kTGF3Q/TH5rymoKAfI/AAAAAAAAfOc/rZB8Y0pn9tY/s400/4938711963_bcd65ed41b_b.jpg

I just found this pic in an Argentinean forum, he is Edoardo Bianchi, an Italian cat champiom, but no mention about the boat.

[Doug Lord]

Apparently he is sailing a boat designed and developed at the University of Genova(Genoa?)-sort of a mini-hydroptere with the same foil configuration:

[SteveMellet]

How much slower do you think it is on foils than it would be if it were sailing ?:D

[onedream]

The boat in the picture is White Dragons (english translation of the surnames of the two designers Bianchi and Dragoni). They are in fact graduating in nautical engineering in La Spezia University. Bianchi has been an italian olympic crew on Tornado. The cited Professor Edward Canepa which supervise the project, is himself a great catamaran sailor, crew in many campaigns with Stephan Griesmayer (of European and World Hobie Cat fame)and Marcolini. The boat is based on two Bimare V1 A class hulls. Sails and mast come from a Tornado. Transoms, rudders and foils are custom and were built by Riba a carbon fiber italian specialist (Ferrari F1 supplier, by the way). Overall the project, in spite of a very small budget, is proving successfull. First test demonstrate a very good flyng ability with very low wind speed. Actually this is the first promising italian sailing foiler coming from Italy after 30 years oblivion.

[Doug Lord]

Thanks to DiasDePlaya and onedream for the very interesting info on the mini hydroptere-appreciate it!

[Submarine Tom]

Doug,

I concur, outstanding contribution to your thread.

SteveMellet,

Your question is very confusing. Do you mean: How fast on foils compared to on pontoons? I would guess four or five times faster, maybe more!

-Tom

[SteveMellet]

Sorry Tom, it was a joke, hence the smiley.. with a reference to all the recent interest in the LAC, wings, foils etc it was interesting to note that Fred Eaton & Magnus Clarke tested full foiling in a 2-boat testing period, and found the non-foiler to be faster than the foiling cat around a race course, and sailed the non-foiler in the previous LAC to victory.
Of course his foiler (Rocker) was a different foiling configuration to this one, which looks similar to Hydroptere in concept.
My comment, though in jest, is still a viable question : Will full foiling actually improve boatspeed that much in an already highly efficient boat design ? Catamarans already have highly efficient hulls, curved boards assist in reducing the drag associated with loading the one hull up more when flying a hull, so will full-foiling catamarans be quicker around a race course ? From Fred & Magnus` observations, the non-foiling cat was already doing speeds that the boat on foils could only seldom match in real sailing conditions.
Foils have been fitted to windsurfers too, and while it acchieves the objective of raising them clear of the water, it is slower than a planing windsurfer - so foiling, while acchieving airborne flight, may not always be the answer to going faster.
Having said that, the pictures of the boat in this thread shows it on foils in virtually glassy conditions, if it can foil with such light winds then it is impressive.
I`d like to hear more about his boat when they are logging their speeds, so we can see..And if it were to race against an equal platform in all respects without foils, then we`d have a comparison to analyse. Although I doubt a 5,5m cat that is 4m wide is a good idea, when not on foils.

[Doug Lord]

Sorry Tom, it was a joke, hence the smiley.. with a reference to all the recent interest in the LAC, wings, foils etc it was interesting to note that Fred Eaton & Magnus Clarke tested full foiling in a 2-boat testing period, and found the non-foiler to be faster than the foiling cat around a race course, and sailed the non-foiler in the previous LAC to victory.
Of course his foiler (Rocker) was a different foiling configuration to this one, which looks similar to Hydroptere in concept.
My comment, though in jest, is still a viable question : Will full foiling actually improve boatspeed that much in an already highly efficient boat design ? Catamarans already have highly efficient hulls, curved boards assist in reducing the drag associated with loading the one hull up more when flying a hull, so will full-foiling catamarans be quicker around a race course ? From Fred & Magnus` observations, the non-foiling cat was already doing speeds that the boat on foils could only seldom match in real sailing conditions.
Foils have been fitted to windsurfers too, and while it acchieves the objective of raising them clear of the water, it is slower than a planing windsurfer - so foiling, while acchieving airborne flight, may not always be the answer to going faster.
Having said that, the pictures of the boat in this thread shows it on foils in virtually glassy conditions, if it can foil with such light winds then it is impressive.
I`d like to hear more about his boat when they are logging their speeds, so we can see..And if it were to race against an equal platform in all respects without foils, then we`d have a comparison to analyse. Although I doubt a 5,5m cat that is 4m wide is a good idea, when not on foils.
=================
Steve, the non-success of Rocker follows a long line of small catamarans that have been slow on hydrofoils-particularly fully submerged multiple foils.
Starting with Icarus,a converted Tornado with surface piercing foils, up thru Caliope and others the performance of cats on foils has usually left something to be desired. Exceptions include Spitfire and a few others.
Throughout the history of foiler development most boats have had three to four foils or more which brings in lots of surface piercing drag and the drag from lots of foil tips. In my opinion the biggest development in sailing foilers over the last hundred years has been the Moth with just two foils. Recently a Moth paced Invictus(!) and Moths have beaten every beachcat under 20' and paced a Tornado. I'm convinced that the number of surface piercings and tips will tell a lot about a foilers potential.
The Windsurers on foils are an interesting study. The windsurfer on the Miller foils has proven faster than planing windsurfers according to Miller. The Rush Randall foilboards use a variation on the air chair foil which is a fairly high drag foil that is optimised for re-entry after a jump-which it does spectaculary well.
Foilers that use surface piercing foils where the foil that pierces the surface is also the lifting foil have an advantage in that, properly designed, there immersed foil area is nearly always optimum-not too much not too little(except, maybe, just before takeoff). They have a disadvantage, in most surface piercing incarnations, in that the foils do not generate RM like fully submerged foilers can(Rave ,Long Shot, Hobie Trifoiler). So they have to carry ballast as Spitfire and Hydroptere do. However, Tom Speer has suggested that a system could be devised using surface piercing foils that DO develop RM.....He and Dr. Bradfield have also suggested that carrying ballast may be better than using foils for righting moment.
For future development I think that a large monohull foiler using just two foils and movable ballast(like Hydroptere) could be very, very fast.
See: http://www.boatdesign.net/forums/sailboats/60-20-ocean-racing-monofoiler-design-discussion-15143.html

[Doug Lord]

This is an analysis I did in another thread-check it out:

Numbers: THE ANSWER!

--------------------------------------------------------------------------------

===========
Mirabaud 26'
--
Foils- two fully submerged foils, one on daggerboard ,one on rudder:
a. mainfoil area= 3.77 sq.ft.
b. rudder foil area= 3.77 sq.ft.
c. mainfoil loading*@ 80% of sailing weight= 191.4lb./sq.ft.
d. rudder foil loading* @20% of sailing weight= 47.85lb./sq.ft.
* rudder foil loading changes in sailing
e. SA/ws on foils including immersed part of struts: 19.1/1
f. W/SA= 2.54
-----------------
Rocker 27'
--
a. mainfoil area=3.34 sq.ft.(two foils at 1.67 sq.ft. each)
b. rudder foil area= 2.6 sq.ft. (two foils @ 1.3 sq.ft each)
c. mainfoil loading*@ 80% of sailing weight= 183.23lb./sq.ft.
d. rudder foil loading* @ 20% of sailing weight= 58.84lb./sq.ft.
e. SA/ws on foils including immersed part of struts: 23.18/1
f. W/SA= 2.55
----------------------------------------
This is the first time I have compared the nearly equal Mirabaud MONOFOILER
with Rocker-the C Class MULTIFOILER and the results are startling.
The two boats are virtually equal in foil loading and SA/ws on foils; both are
better than the Moth in these respects. In racing that has been done in Switzerland we know that the Moth and Mirabaud were virtually equal in speed last year. We know that the top speed of the moth is 30+ knots and that the top speed of a C class cat is 23 knots and that Rocker was generally slower than the top non foiling C Class.
-----------------
Why? When I was first getting in to hydrofoil design I read and was told by Dr. Bradfield that surface piercing drag was a large drag consideration for any foiler. And almost everyone soon learns that the tips of hydrofoils can be a large source of induced drag when the boat is on foils.
Look at this while keeping in mind that the other technical details of Rocker and Mirabaud are nearly the same:

Rocker-
a. number of foil tips= 8
b. number of surface piercing struts= 4
----
Mirabaud-(and any other bi-foiler!)
a. number of foil tips= 4
b. number of surface piercing struts = 2

=============================
This is not a 1.3% difference-this is a 200% difference-Rocker has TWICE these drag producing elements with the other statisics very nearly equal! Very likely a large part of the reason a four foil catamaran is slow......
-------------------
Thanks to Thomas Jundt for the Mirabaud numbers and to Steve Killing for the Rocker numbers that made this analysis possible

[SteveMellet]

Doug, that`s an interesting comparison between the cat foiler & the mono, that the figures you show are so similar yet performance is not. I`m not that mathematically inclined but you`ve made it simple enough for me to get the idea.
I believe the windsurfer foil I have seen (only through internet) does not produce a fast craft as the foil is on the fin, while the mastfoot is far forward of it, so if the sailor were to sheet in hard it would just nosedive - there is a youtube video of it where you can see the sailor standing upright and sheeting out in gusts to keep it balanced. Perhaps two foils like the moth would work better ?
Regarding the foils by Mr. Miller (I have not seen these), it`s much easier to claim something than to do it - if this were true then Hydroptere`s record would belong to him, as anything with a marked performance increase over a speed-optimised sailboard is going to do 55-60knots - that would only require a 10% increase on their current speeds. If foiling windsurfers are much faster than non-foiling ones, where are the records ?
Back to the White Dragon cat.. It seems to be flying in absurdly light winds, by appearances it is not more than 5knots on the water in the photos. That is amazing. I would like to see how they go with it on GPS - could this be a moth-killer ? If it can foil in such light wind, it might just be.

[Doug Lord]

Doug, that`s an interesting comparison between the cat foiler & the mono, that the figures you show are so similar yet performance is not. I`m not that mathematically inclined but you`ve made it simple enough for me to get the idea.
I believe the windsurfer foil I have seen (only through internet) does not produce a fast craft as the foil is on the fin, while the mastfoot is far forward of it, so if the sailor were to sheet in hard it would just nosedive - there is a youtube video of it where you can see the sailor standing upright and sheeting out in gusts to keep it balanced. Perhaps two foils like the moth would work better ?
Regarding the foils by Mr. Miller (I have not seen these), it`s much easier to claim something than to do it - if this were true then Hydroptere`s record would belong to him, as anything with a marked performance increase over a speed-optimised sailboard is going to do 55-60knots - that would only require a 10% increase on their current speeds. If foiling windsurfers are much faster than non-foiling ones, where are the records ?
Back to the White Dragon cat.. It seems to be flying in absurdly light winds, by appearances it is not more than 5knots on the water in the photos. That is amazing. I would like to see how they go with it on GPS - could this be a moth-killer ? If it can foil in such light wind, it might just be.

================
Steve, the Rush Randle air chair foil does have two foils-linked by a tube. Its just that the "main foil" is a delta shape specifically designed for more or less safe re-entry after a jump. Tinho Dornellas(Caleema Windsurfing) and I tried a Moth foil with a rear foil further separated than the air chair foils but the results were inconclusive-mainly because it required too much of Tinho's time to master. I don't think it would jump very well.
I don't know much about Millers foils but some that do think his system works well but that might be within a narrow range-I just don't know.
Brett Burvill(AU) was the first person to win a race using hydrofoils in the Moth class and his foils were surface piercing foils. Both he and John Ilett reckon that arrangement was fast but I don't think it could beat a bi-foiler even given equal development time(but Burvill does). The bi-foiler has some inherent advantages such as being able to be sailed with veal heel that improves upwind vmg and increases RM. But who knows-development of Burvill's system was stopped because the Powers That Be ruled that it was a catamaran configuration.
There is all kinds of potential left in foiler experiments with configurations like that. Look at the MPX-11(12) thread for a "foil assist" + planing hull configuration(in detail) and note that the new "Hydroptere.ch" has a planing catamaran configuration with variable geometry stepped hulls see the Hydroptere thread.

[Doug Lord]

Thanks to DiasDePlaya and onedream for the very interesting info on the mini hydroptere-appreciate it!

-------------------
More info: http://www.facebook.com/pages/Whites-Dragons/145919742107493?v=info

[Doug Lord]

This is cool: you can see the lift from the curved foils!

http://www.youtube.com/watch?v=82CDZcpqyNU&feature=player_embedded#!

[Doug Lord]

Interesting comments about curved lifting foils on USA 17 and on the Nacra 20 including "J" foils vs constant curve foils:

http://www.proboat.com/daggerboard-debate.html

[Doug Lord]

Marstrom 20 being fitted with a wing rig:

http://vimeo.com/23982224

----------------
Provisional results show the NACRA F20c with curved foils beat the M20 with curved foils and a wing.