AC 36 Foiling Monohulls

Discussion in 'Sailboats' started by OzFred, Sep 13, 2017.

  1. OzFred
    Joined: Nov 2015
    Posts: 509
    Likes: 56, Points: 28, Legacy Rep: 16
    Location: Earth

    OzFred Senior Member

    Good, that means you should be able to specify and build exactly the boat you want.

    I think you're avoiding the fundamental point that CT249 is making, which is that making a class more technical and using higher technology design, construction and materials does not, of itself, make the class more popular. You seem to be aguing exactly the same point, except you think it's a lack of vision from designers and builders who haven't managed to build your ideal craft yet.

    I strongly encourage you to pursue your dream, perhaps the Quant 17 can offer some further inspiration. The Quant 17 Foiler thread also contains information about a foiling Flying Dutchman (fairly agricultural but very much in the spirit of you ideal boat).

    Now can the conversation please return to the AC75 class, which I think is the antithesis of your low tech, low speed foiling dinghy.
     
  2. griffinb
    Joined: Jan 2018
    Posts: 18
    Likes: 0, Points: 1
    Location: USA

    griffinb Junior Member

    Anyone heard more about the AC75 wingsail mains? Requirement is that they cannot be craned in and out every day, so must be hoistable?

    I would welcome some more development dollars being put towards practical wingsail design solutions...
     
  3. David Cooper
    Joined: Jan 2015
    Posts: 155
    Likes: 11, Points: 18, Legacy Rep: 42
    Location: Scotland

    David Cooper Senior Member

    Indeed, but the sticking point is the expense of evolving the foils towards something that will settle down towards the ideal, and that's something the AC boats could have driven forward with a lot of money being thrown at it (more than is available to do this anywhere else), and despite my greater interest in lighter-wind performance, I think the best solution for that will also be faster than existing passive systems at the high end. The main compromise is that the kind of boat I want would be carrying more foil that isn't in the water at high speeds, and that extra weight and windage harms race performance when it isn't needed. There would be a considerable overlap in the designs. We know what works best with T foils, so we already know what the AC boats will be doing with theirs. We haven't got passive foils right though - uptips are poor upwind, while Z foils generate two much of their lift in opposite directions and produce roll. All solutions, whether for small cruising foilers or big full-on racing beasts, will need to make advances that will take them in the same direction with their main foils, and that means finding ways to generate lift from surfaces that are tilted in the right direction (rather than the wrong one with uptips), and less steeply tilted (than Z foils) while retaining adequate heave control. I think there's a solution waiting to be explored (a staggered T which would allow upwind foiling on one main foil with its lifting surfaces angled at 20 degrees), and if the AC had taken a different path it would certainly have been explored - if it works as well as I hope, we would have seen a well-tested version of it in action within a couple of years instead, massively reducing the delay before this finds its way onto other platforms relevant to ordinary sailors. That is all I ever wanted to say here - everything else has been in response to unnecessary objections to the perfectly reasonable idea of making boats which provide us with sailing of the exact same kind we already have for practically the same cost while also giving us the ability to add foils (in ways that involve no modification to the boat) for comfortable flight if or when we want it in suitable conditions, and it was perfectly reasonable to link that to the AC, because the AC, despite the differences in scale and purpose, would have been able to help drive the development of the foil solution that would be best for this.
     
  4. CT249
    Joined: May 2003
    Posts: 1,275
    Likes: 101, Points: 63, Legacy Rep: 215
    Location: Sydney Australia

    CT249 Senior Member

    David;

    I have to add one thing - it is completely wrong and against forum rules to accuse me of "behaving like a troll" and of "uncivilised behaviour" because of my references to your claim that designers lack vision.

    The claim I referred to was in post 247. You said you want a foiler for "island hopping in archipelagos such as Orkney, Shetland and the Western Isles of Scotland, plus the occasional more daring trip out to isolated islands further out if the weather allows it... - it is something that could become mainstream once boat designs cater for it, but current designs make it extreme because they simply haven't had the vision to get their boats right."

    It is therefore incorrect for you to say that "The "lack of vision" bit related to designers of boats failing to provide one very specific kind of functionality which could have been given to their boats with small changes which would have made a negligible difference to the cost". There is no "small change" that would make a current foiler suitable for such work and there is no "small change" that would give a current cruising dinghy the foiling performance you demand. It is not a "lack of vision" that is the problem as your remark asserted.

    Please also note that your allegations in your last post are incorrect. There ARE ways around the issue of technological overshoot and they DO work. And it is unreasonable to claim that actually raising independent research is "status worship".

    Sorry to divert the thread further, but one can defend oneself from being called a troll when the thread asks "Will AC75s be good or bad for sailing?" and one tries to bring up relevant research (not opinion, but actual study from sources including industry, history, academics and statistics) on the issue.
     
    Last edited: Jan 31, 2018
    Munter likes this.
  5. OzFred
    Joined: Nov 2015
    Posts: 509
    Likes: 56, Points: 28, Legacy Rep: 16
    Location: Earth

    OzFred Senior Member

    A foil that is "ideal" for an AC75 will likely not be ideal for a dinghy. Even Moths use two or three different foils to optimise performance in a wind range of 6 to 25 knots. There have been a number of well respected manufacturers of Moth foils as well as many tinkerers (some of whom make foils just as good if not better than anyone else) building foils over the last 10 years or so. If it was possible to design an ideal foil (or even a good enough all purpose foil) for even the limited conditions in which Moths sail it would have been done by now. So to think that the foils being developed for the AC75s will have new features that are useful for boats one quarter their size with a completely different set of design parameters is somewhat optimistic.

    I think that is extremely presumptuous. I don't have any idea what the AC boats will do with their foils other than they will be nominally T foils, particularly as they'll incorporate 1,500 kg of ballast. Maybe some will use a flapped L foil, or something similar to those from the AC50s?

    I think your boat is so different from the AC75 class that there will be very, very little that you can draw from their (yet to be developed) foil design. You may be able to draw something from the articulated arms if you intend to have them, but I suspect the electrical and mechanical components would be well beyond your practical cost and weight limits.

    But I think you should wait and see, because comparing one bit of vapourware to another is not that useful. :cool:
     
  6. Doug Lord
    Joined: May 2009
    Posts: 16,672
    Likes: 339, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    I'm not sure David is too wrong: the UptiP foil developed by TNZ in AC 34 has trickled down to numerous applications from models to 100' maxi tri's. I tend to think that there is unlikely to be such a profound foil design breakthru in 36 but you never can tell.....
     
  7. David Cooper
    Joined: Jan 2015
    Posts: 155
    Likes: 11, Points: 18, Legacy Rep: 42
    Location: Scotland

    David Cooper Senior Member

    You have misinterpreted that post, but I've made it repeatedly clear which things the "lack of vision" description was tied to, and you keep ignoring that and trying to attach it to other things. Please desist. In that bit you have quoted, I was referring not to a foiler, but to a dinghy designed for cruising by making simple changes to make the boat properly suited to such trips so that it's comfortable to sleep in - simple changes like an easily-removable thwart and buoyancy tanks being shaped to give you enough shoulder room between them and the CB case. When I talked of going out to remote islands, that was a referrence to places like St Kilda where you can land. It's rocks like Rockall that would be ill advised for a small monohull dinghy unless it can have its speed amplified considerably by hydrofoils (and obviously for the trip be made in a suitable weather window). At no point have I said that not designing boats for hydrofoils is down to lack of vision - the non-foiler designs that are out there today were conceived before hydrofoils looked practical, and they still aren't available as a fully practical system for this even now. To get there, you want to have something at the front end like they have on C-fly, although there's no need for the boat to rest on them all the time in the way that C-fly does. What I envisage is this - you need a front rudder (or two), and a rear rudder (or two on a cat), and the front one would have a V or diamond foil on it with twist to prevent pitchpoling, but the lifting part would be a short way above the water in stable flight, while the vertical part would go down to the same depth as the bottom of the main foils (and trigger the detatchment of all the other foils if it hits heavy debris). The rear rudder would have winglets at the bottom - a standard T, not generating lift, but merely acting like the tail of a dart (this at the same depth as the bottom of the main foil), while it would again have a V or diamond higher up like the front one. This should provide better pitch stability than C-fly and have less drag. Now, I don't blame current foiler designers for lack of vision - this stuff's new and needs to be pioneered.

    "Please also note that your allegations in your last post are incorrect. There ARE ways around the issue of technological overshoot and they DO work. And it is unreasonable to claim that actually raising independent research is "status worship"."

    Then why have you failed to revive windsurfing? Surely it's in the interests of manufacturers, shops and competitions to suppress all the high-tech stuff so that it doesn't put off the punters, but they haven't done so. And the "status worship" part relates to your appeal to a dubious authority which makes unsubstatiatable claims.
     
  8. David Cooper
    Joined: Jan 2015
    Posts: 155
    Likes: 11, Points: 18, Legacy Rep: 42
    Location: Scotland

    David Cooper Senior Member

    In terms of foils in the water, it's essentially going to do the same as the Vampire (except for the single central rudder instead of two on opposite sides), but with lots of heavy complications in getting the foils into place. The angle of tilt of the foils will be the same as the Vampire uses, so there's little new to explore with that. The shaping of the foil and its flap will doubtless push a bit further into an area of diminishing returns, so it will uncover some new knowledge which will pass on to other foilers (of all sizes) using Ts & flaps and lead to small gains there, so it's not such a terrible waste of money pouring it into this, although a massive proportion will go into the heavy engineering instead of anything transferable to practical boats.
     
  9. CT249
    Joined: May 2003
    Posts: 1,275
    Likes: 101, Points: 63, Legacy Rep: 215
    Location: Sydney Australia

    CT249 Senior Member

    David, it is not worth discussing the issue of technological development in sailing with you since it appears that no matter how much evidence in the form of statistics, information from designers, history, studies, surveys, independent reports and personal experience (as a sailor and in the industry) one can summon up, your answer will essentially be that you know better - even in areas in which you no experience whatsoever.

    PS - since your reference to lack of vision was 20 lines away from your reference to sleeping accommodation you can hardly blame people for not seeing the link. The main point is that you appeared to be assuming that the designers lacked the vision to see an easy solution, instead of assuming that you had anything to learn from them and their answer to the issues involved.
     
    Last edited: Feb 2, 2018
  10. CT249
    Joined: May 2003
    Posts: 1,275
    Likes: 101, Points: 63, Legacy Rep: 215
    Location: Sydney Australia

    CT249 Senior Member

    Sorry Gary but your facts are wrong.

    1- It's incorrect to say that One Raters had no ballast. Plenty of them did. Challenge of 1892, despite being built for the Thames, had 1000lb. Mirage, another Thames One Rater, had 336lb on the keel and 1288lb on the centreboard. Gaity Girl, a Clayton, had a 609 kg board.

    2- Reliance was very light for her day and size and her DLR was 192. A late radical One Rater like Unorna had a DLR of 148. A middleweight One Rater like Kitten had a DLR of 173. A heavy one like Kemp's Dolly had a DLR of 230.

    By the time Reliance came out the introduction of the girth measurement had added extra displacement to the small Raters. Sure, there were lighter L x SA rule boats but Reliance was still built to the same rule, just like Kialoa IV was built to the same rule as The Red Lion but heavier.

    3- Reliance, like 15 Footers/Half Raters and their One Rater cousins, was designed to the Seawanhaka Length x Sail rule which was essentially the same as the Kemp rule but for the sail area multiplier. The AC75 is not designed to any rule linking it to small boats. The foiling AC cats were not designed to the same rules as A Class or F16s.

    4- Reliance and boats like it were therefore linked to many small boats because they were built to the same basic rating rules. That does not apply to AC foilers.

    A 12 Metre, for example, was built to the same rating rule as the Sixes of the Solent, Europe and the USA, the Eights of the Clyde and Europe, even the Fives of Scandinavia. A 12 Metre is also is quite similar to a typical offshore racer to race on - I've done bow on a former AC winner in a regatta and the techniques, design and gear were very similar to that of the typical yacht seen in Auckland, Cowes or Newport. Twelves were raced in the main fleets of the world's biggest events, such as the Fastnet and Cowes Week, SORC, Bermuda, Ensenada, and Hobart. The Barcolona started with a 12 race, I think. The 12s were therefore closely linked to the main yacht regattas.

    In contrast, a winged foiler is not very similar to any typical boat seen anywhere in the world.
     
  11. CT249
    Joined: May 2003
    Posts: 1,275
    Likes: 101, Points: 63, Legacy Rep: 215
    Location: Sydney Australia

    CT249 Senior Member

    Sorry for the further hijack Fred. I've put people on ignore and will bail out.
     
    Last edited: Feb 2, 2018
  12. Gary Baigent
    Joined: Jul 2005
    Posts: 3,007
    Likes: 121, Points: 63, Legacy Rep: 509
    Location: auckland nz

    Gary Baigent Senior Member

    Sorry CT but the Napier Patikis and One Raters from New Zealand were unballasted. There is a story of two men from Bailey and Lowe or Logan Brothers lifting a Napier Patiki; they didn't run around with it but lifting the 27 foot boat was not a huge effort. And that is understandable when you read of their construction, low freeboard, hollow masts and so on.
     

    Attached Files:

  13. David Cooper
    Joined: Jan 2015
    Posts: 155
    Likes: 11, Points: 18, Legacy Rep: 42
    Location: Scotland

    David Cooper Senior Member

    I have no doubt that you have collected lots of statistics, but you've never managed to show that they back your conclusion. You attack the hype about foiling and blame it for a loss of interest in ordinary sailing, but ordinary people aren't listening to that hype - they're simply getting occasional glimpses of high-end foiling machines on TV, and they're being buzzed by the odd Moth in real life. What do you want to do about this that wasn't done with windsurfing? With windsurfing, was it hype that did the damage? What hype was there? Was the damage actually done by the sight of more technical and more expensive equipment in shops and out on the water? How do you propose to apply the lessons you've learned? Do you want Moths and other foilers to be banned so that ordinary people won't see them? I assume, not. Do you want promotion (hype) of foiling to be banned? I doubt you want to ban promotion, so how do you ban hype? Who decides which is which? The worst thing I've seen in hype is the line about foiling being "the future of sailing", but does that actually do harm when it's such a common form of overstatement used in every field? Do you have evidence of this happening with hype with windsurfing? I assume no one said that windsurfing was the future of sailing, but if they did, you should be blaming that hype for harming dinghy sailing. But more importantly, what was the hype that specifically killed ordinary windsurfing? The mechanism you've described doesn't appear depend on hype, but the existence of higher-tech equipment with higher cost and harder to use that people directly saw on the beach and out on the water in the real world, so how do you prevent that happening without a ban on progress at the high end? This is the key thing that's always been missing from your expert analysis - you've never shown that you have any ability to prevent the damage being done, just as you haven't found a way to revive windsurfing based on this expert understanding of the cause of the decline.

    So, what exactly is your plan for saving sailing? Is it about clamping down on foiling or talk about foiling? I don't want to put words in your mouth, but I think you want the AC boats to be non-foiling monohulls so that they don't promote unrealistic aspirations for ordinary sailors. Will that really help though as more and more foilers like the UFO begin to appear on the water in the real world of ordinary sailors? Was there an equivalent of an AC for windsurfers that killed the sport which, had it not existed, would have enabled ordinary windsurfing to continue to ride its craze for decades despite the arrival of more and more expensive, faster, harder-to-use kit? The windsurfing boom was a craze. Dinghy sailing isn't. The situations don't match. The lessons you've learned from one appear to be wrong (in that there was nothing that could be done to prevent the decline of a craze), and you're now trying to transfer them to something very different in nature.

    What do your surveys tell you? Do people actually tell you that they've given up sailing because they saw foiling AC boats or heard some hype about foiling being the future of sailing? I don't think so. Do they say they want to see non-foiling monohulls in the AC and that that would inspire them to get back in their dinghy? I very much doubt it - there was practically no audience for the AC in the monohull days, and they hardly even registered until they started hiding keels behind blankets. How do you guard against a survey asking leading questions that suggest something to blame which people then appear to confirm by agreeing with it? Your case is totally unconvincing, so if it's stronger than it looks, you seriously need to think about how to present it properly, setting out the evidence to back each point relating to my questions. But wait a minute - you must have done this already in a thread dedicated to this exact subject, so where is it? We should be discussing it there rather than here.

    "PS - since your reference to lack of vision was 20 lines away from your reference to sleeping accommodation you can hardly blame people for not seeing the link. The main point is that you appeared to be assuming that the designers lacked the vision to see an easy solution, instead of assuming that you had anything to learn from them and their answer to the issues involved."

    I repeatedly clarified what it referred to afterwards to remove all doubt. I can understand you misinterpreting it on the first reading as that's easy enough for anyone to do, but whenever you subsequently attributed the lack of vision part to the wrong thing, I made it fully clear that it only applied to the design aspects relating to making dinghies better suited to cruising so you can camp out in them without having to do such things as carry planks of wood along for the ride.
     
  14. Dolfiman
    Joined: Aug 2017
    Posts: 1,312
    Likes: 535, Points: 113
    Location: France

    Dolfiman Senior Member

    There is a 4 pages article on AC75 in Seahorse Feb. 2018 :
    "To boldly go" That AC75 - Franck Cammas, Grant Simmer and Dean Barker talk to James Boyd

    All aspects are discussed, among which the need of some "proof of concept" step(s), especially in relation with the definition of the one-design parts. The take off phase is challenging, as the AC75 seems to be impossibly light, is the extra sailing surface needed in excess with the one needed for full flying at high speed ? It is question of a hull "sheer" beam limited to 5,4 m, a free hull design within a rule box.

    Bizarre that among all the uncertainties, hull-struts-foils stiffness requirement is not mentioned, given the high cantilver arms moreover ballasted (>> low eigenvalue mode of vibration), the need of foils flow incidence high control , the need to avoid flutter vibrations....The Jean Sans proposal to have foils in steel and struts in carbon, to improve the RM for pre take off phases, seems very risky from that point of view. The load on the shoulders of the structural engineer in chief will be heavy...
     
    Doug Lord likes this.

  15. AlexanderSahlin
    Joined: Oct 2014
    Posts: 85
    Likes: 48, Points: 18, Legacy Rep: 29
    Location: Sweden

    AlexanderSahlin Junior Member

    The proposed AC-75 for the next America's cup will be unnecessarily complicated, heavy and expensive. It can be done much simpler, more reliable and more efficient. Therefore, I wrote the attached file. This is a short version of a somewhat longer article I submitted to the newsletter of the International Hydrofoil Society.
     

    Attached Files:

    Doug Lord likes this.
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.