Francis Joyon sets new solo 24 hr record on IDEC II

I'm not a nitpicker in the slightest Silver Raven. This is a boat design forum not a place where we should worship at the altar of a design feature. The curved foils are a useful addition if integrated into an optimised platform. Look at the A class catamarans that your mentioning the boats rigs have become progressively lighter in weight and high aspect with a good understanding of appropriate sail shape, mast sections are at optimal fore and aft deflection thanks to continued testing of the boats relative to crew weight, the hull shapes are optimised to a high level and the platforms are at minimum weight logically the only area where you can eek out an advantage moves to areas like rudder foils and daggerboards and the nut on the helm steering the thing.

 

Worship

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I don't think anybody is "worshipping at the altar of a design feature". There is no other specific design feature added in the last 40 years for ocean racers that has been responsible for such important and far reaching performance and handling enhancements as has the curved ama foil-thats just a recognition of reality. When a small, bent piece of carbon carries 70-80% of the weight of the boat at high speed it's simply hard to ignore.
When nearly every performance multihull is using that bent piece of carbon, it must be a pretty significant design feature.
I think the full importance of the addition of lifting foils to sailboats is not appreciated by most sailors , though that is changing painfully slowly....

 

I think that the design development of trimaran hullshapes has had a greater impact on the overall handling of boats than curved foils. The greater understanding of those areas has allowed lifting foils to show their benefits. I'm a big enough man to agree to disagree with you, can you do the same? Or will we to and fro for another ten pages cluttering a post about the achievements of Francis Joyon?

 

Is not a case where the skipper and the boat set the record? If it was not sailed well by the skipper it would have been achieved, and if the boat did not have the potential once again the record would not been archived.

 

But Idec didn't have them for the round the world record, added later for the route du rhum

 

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And it was Joyons experience in the round the world race that convinced him that foils would make a big difference....

 

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These days on high performance tri's or cats designed from scratch, the hull design is matched to the foil system-not the foils matched to the hull design.
This subject is important and is relevant to this thread since it was Joyon who made the decision to add foils to Idec!

 

Pitch stability is drastically better now than it used to be.

The rocking back and forth, the crashing down into the next wave both slow things down and greatly increase structural loads. A major limit on how hard you could push was the threat of a nose going under.

Good pitch stability is absolutely required at the speeds we are talking about.

Hull design alone was never going to get pitch stability where it is today. However, I see room for much more advance in pitch stability. In the Hydroptere thread, I recently posted info on their attempt at automatic active pitch control. The success or failure of this one feature is probably huge as far as getting this boat successful for open sea records.

For once, I do not think Doug's claims for foils are really that far out of line. We are talking about "trimaran handling and speed at sea".

If you take away massive carbon content and super optimization of structural requirements, you end up heavier. Heavy is more of a problem in light air. Therefore, I would say that these improvements are huge for around the world and better potential results for some races, but not as much of an improvement in top speeds in strong conditions where "handling and speed at sea" would be the context.

 

Unfortunately thats why it's impossible to have a rational discussion with you about foil assist. Of course the float shape is optimised for foils if you dont optimise the shape you dont get the maximium benefit from them. It's the interaction between the foil and the float hull that makes the system work not the operation of the foil system in isolation. Even on hydroptere there has been ongoing work on the shape of the floats to provide a soft landing when the foils ventilate and to provide decent light airs performance. Sadly you seem incapable of reading my posts in the context which they are presented which is favourable towards foil assist as part of an integrated system.

An extract from Erwan Le Roux on his Multi 50

The boat is incredible because she lets you reach high speeds while feeling always safe. We needed to take a reef sometimes and there was someone at the mainsail trim all the time, but we never nosedived or crashed heavily. The boat is extraordinary. I'm convinced that a 7 days record is still possible with a Multi50, we made a lot of extra miles, especially towards the finish, but if one can make some gain all over the course, the record is feasible.”

So different design approaches can have merit and still deliver a fast boat with good handling. If you could concede this point we could get on with having a reasonable discussion.

 

Thanks for contributing to the discussion. The ability of the modern record breakers to perform well in a range of conditions and the overall increase in average speed has been the main driver of record improvement. It's amazing that a current design can double windspeed in light conditions and yet still have high top end speed as well. A case in point is the Jules Verne record when it was held by Bruno Peyron on the maxi catamaran Orange the boat went exceptionally well in heavy wind conditions but was "sticky" in the light. The modern generation of trimarans are both able to log high averages in light conditions but have a high top speed and good windward performance in the same package. Foils are a useful contributor to that high performance when integrated into the system and "assist" the whole package. I guess the problem I have with Doug's emphatic statements are that so many factors have to be "right" before foils make a difference. The sails have to be right, the platform has to be light and strong enough and have sufficient beam it's the interaction of a slew of other design factors that conspire to make foil assist useful.

 

Some advice - from an 'old' man

Gooday to everyone in this section of 'forums' -

The original title; FJ & 24 hrs (just to keep it short)
What a great subject - YES
What a grand achievement - - YES YES

If - some - - well meaning people - wish - for whatever reason - to discuss - long winded - subjects - whatever they may be - - for whatever reason they choose -----PLEASE ------- have that discussion ----- in the proper place.
By all means - have-it - but ----- in the proper manner & correct 'forum'.

Every single item in every vessel - 'conspires to make-up the success of the whole'
Take one single item out, change it, modify it, move it, etc etc - changes EVERY other single item & it's effect on the 'whole'.

Can we please - return to discussing - plus type developments in vessel-improvements - as a whole & not get bogged-down in - good - gooder - goodest - - better - better'er - better-est. PLEASE.

I'm positive - having been-here - for at least a few years - that we are all wanting to - improve - our knowledge & understanding & not go backwards getting bogged-down in - this endless meaningless carry-on - about the degree of importance (of which rung on the ladder is the most improtant0 because - - it's doing this subject & this forum - a great dis-service.

I M H O so here you have my opinion. Back on subject - which should have never been - changed - - What I'd like to know is how he continues to do it. What has his trailing been - how does he continue to improve - etc - etc & more important can someone - go & find-out & come back in here & let us all know - - so we can follow his very effective learning-curve. Please. Bye for now! ! !! I'll be back - if - this area - returns to - subject. james

 

Hi all,
Thanks for an interesting discussion...

As an observer with no qualifications - design is becoming a meld (is that the right word?) of building a platform where the sailors can maintain as near as possible the 100% potential speed of the boat for the present conditions, and for the crew to feel they are not stressed beyond endurance in maintaining that 100% potential in a boat that may be only 0.1% better than all others racing lets call this "boat A"... That will put that boat & crew well ahead of "boat B"

Lets now consider "boat B" - - A boat can dash at up to 110% for 1 or so hours and for the remaining hours of the shift the crew are physically and mentally "knackered" loosing the margin gained, to the crew and boat "A" where the crew may easily maintain 100% of the boats potential in that sea/wind then the steady performer will have more victories in the long run... There is merit in being comfortable by the reduced stress and avoid the risk of a 'boat-slowing-event'...

Think of a modern fighter jet - these are usually designed to be unstable so as to be able to make duck and dive manoeuvres instantly - whereas a racing sail boat that can take seas and external influences and hold the desired course more consistently, reducing the control and management load on the crew...

My feel is that the weakest link is crew exhaustion through high levels of intense concentration, and that efforts to overcome this issue, without any detriment to design performance so far gained, by developments in structural engineering, hull design / shape, sail and foil design are not lost...

 

Gooday & thanks 'masa' - May I please have -

The 100% of yacht 'A'

With - the "dash of 110%' of yacht 'B'

14 mtrs to 17 mtrs long under 3500 kgs (dry) @ $120k AUD - thanks for that I just knew you'd come up with the answer. ciao, james

 

Curved foils do pay when used on an already good boat. First I've seen that was on a drawing of plans of a C class designed by Harlé for the small America Cup in the beginning of the 80's (the has been never built). Sure someone thought about that before...
That pays truly as the boat becomes more easy to push (keeping an positive angle of attack) but it has a con; if the boat goes over its foils; the foils will pass in negative angle...The true catastrophe, it's so fast that it's almost impossible to react.
The other con is than the sterns must have enough buoyancy...that means that the next step has to be a true foiler, as too full sterns are a nuisance in light weather when the foils are useless, and may be dangerous in very heavy weather.
Foils are useless on a poorly designed boat; they will add only problems to an already problematic design (we have numerous examples of that...)

 

The design and engineering of such boats is far beyond the possibilities of an ordinary naval architect or even a lone very experienced NA, and totally stratospheric for amateurs. It's now the work of design and engineering teams plus a lot of consultants. The foils profiles are not in catalogues, they are specially designed for the purpose. The hydrodynamic and aerodynamic data is well secured in hard disks. Add also very experienced builders; this kind of boats are not feasible with all the reliability needed without the providers and the workers.
I do remark that all the maxi multis made out of France have had structural problems; Sodebo had to been fixed extensively in France. That do not means that the Australian shipyard that made it was bad but they had not all the experience of French shipyards, and the very experienced engineers were on the other side of the earth...The evil is the details; a fingerprint can cause a failure...
There is a synergy in France between military industry and race multis building. One proof is that the Hydroptere is sponsored by DCNS (a French naval and nuclear engineering and building group born from the DCAN). The DCNS is not simply a sponsor looking for a clean image, the DCNS intervenes directly in the conception of the boat and gives a lot a free items like a big bunch of hours of supercomputers (with the programs...), access to wind tunnels, hydrodynamic water tanks, engineering, special tooling, exotic alloys, structural analysis labs etc...And the results will be analysed carefully and maybe used on a military foiler.