Boink

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  1. Boink

    New imoca boats

    But there will be faster boats...... there always are. Q: Why would Charal and six others (including Hugo Boss themselves) build new generation boats to be slower than a four year old design? A: They don't...... Certainly if AT completes the RdeR in current position, it will have done the boat's value no harm, nor his underlying inner confidence. But to suggest that it can't be beaten is ludricrous. Foil design has evolved so much in four years. Moding the boat, its sails, autopilot and learning all the nuances of modern IMOCAs gives the HB team a great advantage. But the RdeR has again showed us how losing foils or other damage can wreck the best laid plans. So there is hope for all competitive entries - provided you can survive the attrition. Please, lets just enjoy these boats at the peak of their popularity, for what they are; and yet still celebrate the adventure that the VG brings.
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    Team NYYC

    Sails look the go. Having Q to rival NS can only be good for the whole sport. Think that large batten 150-200 could well be the primary linking of the two skins and keeping the trailing edge as thin as possible whilst also allowing the small amount of slip that the geometry would occur. I am not a betting man but would wager that the oval section "batten" is actually two halves - split vertically with an internal linkage along maybe the last 600-1000mm of aft most length. The amount of tell tales placed on the sail in PHW's post of #1077 show how much they are trying to monitor any separation bubble both windward and leeward as well has having laminar flow off the trailing edge. It is also definitely a twin skin mainsail that is being tested The two skins of the main sail are clearly visible in the same photo - look at the curved windows - you can make out the lewward windows of the leward skin are clearly separated apart - with the depth decreasing from front to back as the skins taper back to touching each other somewhere aft or around the back of the window.
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    A-Class foiling sailors

    My tip would be to rewatch your videos focusing on your stance - curiously you are giving away heaps of RM with both having a high hook position and and almost sitting stance. Your centre of mass is at your sternum (bottom centre of your rib cage) yet with your sitting type stance it is little further outboard than your hips. Contrast that stance to the top guys - Glen Ashby in particular; you are giving away heaps of RM which may just save you an occasional capsize, certainly need to learn to drive and control the boat rather than have it control and drive you. His stance is feakishly low and utterly upright. Study what they do, before you develop soft and bad habits. Head back, Shoulders back, straighten those legs as much as possible. It will feel uncomfortable and unnatural, and the effort required is much greater - but you will never get max performance unless you train yourself to do this. Play squash over winter. Fast sheet play with no wrapping of that sheet round your hand, whilst steering smoothly. Definitely get some coaching - either in a group or one on one. But nice work on your early outings. Beautiful boat. Keep the faith. If it was easy, everyone would do it....... 25kts soon enough
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    Team NYYC

    There is a Finnish company making Moth main foils that are seamless on the upper surface and sliding surface on the lower. Also allows some anhedral to be utilised which is known to have advantages in that class but has been very difficult to achieve. Also consider that the displacement difference between a moth and an AC75 are going to lead to different engineering solutions - could the strength required to contain the flaps on an AC75 still allow enough flex to be considered a hinge without it being a mechanical hinge? I do not know of any foil design that is seamless on both sides for in water use - it will happen, but think of the geometry going on - the back edge needs to remain attached for reduced drag and early take off (which will be critical) - wedge shaped foils (cavitating design) might have an upper speed rage which ultimately would be faster - but would need a significantly higher take off speed to achieve flight - and the MA foils have been shown to be very fine (knife like) edged and assymmetric in section - so are not of this type. The spoiler on the back of the McLaren - whilst cool, only has to consider flow on one surface - is more crudely generating downforce - with lots of associated drag, rather than trying to generate lift with laminar flow. So if the MA foils are seamless both sides, where is the articulation coming from? - the hull hinges are not rotatable - and there seems to be no articulation space at the rear interface between main foil foil and support strut. If this boat can fly, then AOA trim mosy likely coming from Rudder foil control. The orange tips on the main foils do seem to be "thicker" than the remander of the foil, suggesting that they are covers - but there would be benefits in have high visibilty tips to be easily highlighted to both crew and video footage to more easily analyse what is going on, and give the helm a clearer idea of where the extreme edges of the boat actually are. The whole package does seem to be oversized for the length of boat - but the foils on INEOS are also known to be massively oversized - so probably working to issues of scale and speed for the sake of learning hown to fly smoothly and in control.
  5. This is how i recall it. All foil geometry developed on the mule to give the auto regulating ride hide that they were seeking - some inland freshwater lake out in whoop whoop. Only revealed that this was done after AC72 broke cover. Caught Oracle flat footed..... There are lots of remote lakes in both North and South Island to repeat such a programme. I realise that the UK can be sailed in year round - done it myself - but ripping around at 30 knots with air temps around 0c/32F in Jan/Feb would give a wind chill that might focus the mind in places other than which effect has the latest round of modifications caused. They are not wanting for budget either......
  6. New Zealand have a track record of testing in secret and launching when it suits them....... and not been driven by northern hemisphere calendar, expectations or rumour mongering. Remember how they developed the SL33 cats, how they developed their own AC50. They are smart and beat the drum to their own tune. The fact that you do not see testing in Auckland is not indicative that they are not testing. The foils on the NYYC are what are laughable - no flaps, rudimentary shapes, complete media control, no sailing in anything other than super light airs and obviously therefore no foiling - just not credible. Their deck layout is thought provoking though. Where will INEOS go over winter? Middle East, Carribean, Auckland or pull the shutters down unless good weather......
  7. Boink

    what is it?

    World Sailings latest proposal for gender neutral mixed fleet singlehanded offshore dinghy foiling revenue grab......
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    GB5508 Rebuild - Soma's Project

    Thanks for the update Soma - keep em coming. Nice progress Can you repost the two photos from #68 that refuse to load?
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    New imoca boats

    President of IMOCA is on the record with class concerns about foil size and the implications that the One design Mast will be operating without safety margins and therefore likely to impact the fleets relaibility. T foils would not only up the speeds but also reduce the reliability of the fleet. This was a fleet teetering very close to the edge - recall the spate of dismastings and very newsy rescues that then drove the class move to One Design Masts and Keel packages. By comparison witness the negative press surrounding the in progress GGR. So T-Foils are off the agenda until the new rule of Feb 2021 - when a new round of rules will be announced post VG race. Whatever is announced will have to be retro-fittable to avoid obsolescing a large fleet - which could happen anyway; if all the new modifications are frankly uneconomic to apply to old boats. So it is a bit of a minefield to think that this will be an automatic "given". The class needs to not kill off what is currently a hot space to be in, both for sailors and sponsors - which is the symbiosis that is needed for overall sucess. One cannot exist without the other. Ultims command the stratospheric big sposor territory - The IMOCA's have a mid level package, offering good boat size (read Billboard presence, photogenic and fast), public interest and with the addition of VOR a rolling calendar that keeps teams busy each operating year. But not if the design budgets and build/operating costs go stupid.....
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    Team UK

    Increase in Anhedral of the tip foils can be clearly seen from July 25 photo - first seen to Oct 9 - video clip stills from this thread - photo. There was an interesting asymmetrical shape shown in the Aug 31 photo, but superceeded since. We can only speculate that curved surfaces are harder to interpret what the sailors are feeling/experiencing - whereas the straight sections are both easier to produce and easier to correlate findings for - whether they be outright velocity gains or improvement in control and/or stability, allowing faster prototyping and more design space to be covered with realtime testing. Not unreasonable to expect layout to end up a hybrid of both types - i.e. increased anhedral but with curved surfaces - to allow the best compromise of both speed and control and yet still be capable of being "packed" within the limitations of the rules box space - centreline storage, arc, span, socket length etc.
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    Team UK

    Glad to see we think in similar terms. Where I do differ is the statement in Bold. If you allow the foil to invert to increase leeway, then ultimately the sail rig has less to "lean" on and drops to an overall lower power status. Now, if you are butting up to foil cavitation issues; because total power generated by both hydro and aero foils allows a boat speed in excess of where foil cavitation is induced, then Yes accepting more leeway will keep the whole package on maximum velocity just under cavitation but at a lower course sailed which translates to better overall VMG. But if this threshold has not been reached, then more leeway is not optimal. I think there are many shades of grey at play - dependent on many things. Also the AC75 rule outlines a "Box" that the bifurcated tips must sit within, at the end of the supporting strut - and if I have interpreted it correctly, then 90 degree juctions or even Equilateral type "Mercedes Star" layouts are prohibited. There is absolutely no doubt that Team UK have increased anhedral from first launch - but are probably/possibly at the limit already.
  12. Boink

    New imoca boats

    I believe that this video would help. It is not the instance of the photo posted by Terrafirma - the conditions were not as nice, different tack etc This video is from the Defi Azimut - and the music is cheesy (from a can) bad..... It cuts between footage of the solo offshore start to the fully crewed speed runs. At around a 1.00 minute the boat erupts out of the water - momentarily - to the surprise of the chase crew and crashes back down - not a broach in the traditional sense - but not super fast either - especially when you consider the primary aim of this outing. The results were telling - Charal was more than 10% faster than 2nd and 3rd place. Again context is everything - still photos are cool - often much higher resolution - allowing detail to be seen - but tell the story of that moment only - and have been used and abused too often - especially on these forums to maker a case or refute a statement. Without rudder wings - full flight is NOT sustainable - It will happen, but cannot be maintained.
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    Team UK

    I get all that. That is what I was trying to convey to you that I did understand. What I do not get is your use of the language "to induce negative leeway". It is, frankly, confusing and too open to interpretation - which you have not provided. I am hoping that you are trying to describe that you could generate sufficient (even excess) lift that the craft no longer generates leeway - but actively climbs to weather (upwind at least). Downwind this trait is actually deterimental to VMG. So. assuming that this IS what you are describing - what needs to be carefully considered here is what is actually happening to the whole platform when the vertical foil is twisted to do as I think you are saying. What I think is being missed her is the important distiction between Kite Foils and Windurfers to any other foiling platform with a stayed rig - be that Test Boat or AC75. What occurs is that on kite foilers and windsurfers the vertical element can be rotated independently of the rig which can continue to generate its power irrespective of platform direction. I think that the foil riders can feel throughtheir feet the amount of twist that the foils can run, without stalling or slowing too much. However, this is not the case with a stayed rig. What will hapen is that if the foil is set to generate excess lift - the whole plarform will instead rotate the bow down to leeward until the foil runs back into the equilibrium mode of runnings at an angle in the water where it's drag and lift are restored - i.e. normal(ish) angle of attack through the water. What you have proposed is the eternal debate of gybing centreboards and all that they entail. So if history of these forums is anything to go by ( I think it was a discussion about 14's or David Hollom) ............ well I wish you luck. I do not believe it can currently be done any better than trying to run the whole show at zero leeway with a foil that can trimmed in AOA (either bodilly or through trim tabs) and mimimal size to give the lowest drag possible and thereby create the highest VMG achieveable. Happy to stand corrected and educated by anyone who can make a reasoned argument.
  14. Boink

    New imoca boats

    I agree entirely that the inclined pin has become a double edged sword. I think where my wagons have circled to is that inclined keel pins and their overall sucess is entirely dependent on it being set "exactly" right at the time of build - and we all know that what is right in one scenario, be that speed, trim or sea state will not remain fixed for all time. Foils are increasingly higher aspect, slimmer, narrower chord and ultimately more trim critical. Because ultimately both materials and construction techniques have improved so dramatically that these more efficient shapes are more ideal to employ. The range of speeds that foils they are running through are also greater. Fixed foil shapes and a fixed trim attitude can only be optimised for one type of scenario. The capacity that a commercial jet has to deform a wing shape to suit its 3 modes - take off, cruise and landing mode - is all the inspiration that should be needed to extend the sweet spot that sail boat foils need to improve upon. The lack of rudder control surface is what will ultimately restrict or slow down development in IMOCA's - be that good or bad - not part of the consideration here. This is where I think foils on sailboats can only extend their range of optimisation by having trim tabs, and generally speaking the types of boats we are referring to here are either open development classes, line honours machines or not focused on IRC/ORC issues. Let the development roll.
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    Team UK

    Can you elaborate the part in bold? - seems to be counterintuitive. Agree about the separation of anhedral - but surely having each operate in their separate X and Y axis (i.e. 90 degree perpendicular surfaces) is the optimum for running both at minimum sizes with resultant reductions in drag.