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JulianB

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About JulianB

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    Sydney mostly
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    Sailing, eating, designing

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  1. https://bethwaite360.com/jib-sheeting-angle/ There is plenty here if you search, lots and lots of stuff jB
  2. there are lots of threads at 29er.org, Bethwaite360.com or search this website. What advice are you specifically looking for?? jB
  3. You should follow the Port McQuarie model. Regardless where the next day's clip???
  4. https://bluewave.dk/products/quick-race-tuning-qrt-with-fork-eye/
  5. Firstly, 60% of all the sailors at any given 49er worlds are there for the kicks, not for the gold. Rightly or wrongly, the 49er has become an aspirational boat, in the sense that they aspire to sail it, and some aspire to sail it well with no intention of Gold glory. We could stochastic-aly verify that (you made me look up that word) but again the feedback from the sailors at the AGM, is more than enough for me. Re inconsistency. These guys get bent out of shape over ¼% (as in 0.0025) and to them it’s very real. What I do believe is that 3Di and the claims made by
  6. BOI guy I am getting rather sick and tired of this. If you want to play the SMOD game, you play by the people who sail those classes rules! I think there are 150-180 WS Int classes, there are about 20-30 of those that are SMOD which in all but the case of the RS boats are really MMOD's. [Multi Manufacture One Design] I don't know the number, but I would guess that 4-5 of the MMOD's account for more than 50% of boats sold in terms of $$$ per year. (excluding big yachts, obviously) So a very large proportion of the worlds sailing population chose to play the MMOD game.
  7. If you buy a one off 3Di sail, it's expensive, as it should be, one off setup, design, etc etc etc. Start buying 50-100 at a time, same set up & design cost, but only once, so they end up very cost effective. The biggest thing the sailors wanted was consistency, and 3Di and it's moulds potentially offer that better than any other process. Equally weighted to Consistency was Vision. 49er sailors like to be able to see. 4th was Longevity, I think all the candidates offer Mains and Jibs that would last longer and yes we asked lots of questions, particularly of Moths
  8. Downhaul tension is a primary trigger/control WRT the #1 batten, Cap shroud tension or lack of it is a very secondary control. Pretty interestingly, we are presently knee deep in sail re-evaluation WRT the 49er and the FX, Jimmy, one of the skippers trailing the sails here in Sydney, he is well aware of the loose Caps WRT the FX to get it to flick off, and given that all the sails are now "more firm" giving the upping of the structural components, he is looking at using "more stretchy" dynema, so SK78 rather than SK99 to possibly breath some life into the otherwise "more firm" sails. (t
  9. Yes, putting the tip of the batten on a good set of scales works very well also. When we started doing this, which was in the early 80's, digital kitchen scaless did not exist, and my father was a man of consistancy, so we probably used a very old set of fishing scales, very likely in Lbs untill well into the 2000's. But now with these really good kitchen scales going up to 7 - 10 kgs, it works well. jB
  10. WRT 1. The way I measure battens is to have them vertical, with the tip on the floor, put a spring balance on the other end and pull slowly down while watch the gague rise. At a point (the Euler Crippling Load) the number will cease rising as the batten bends further and further., so you then back off, lift the scale until it just starts to fall (the reading), back and forward a few times until you find the sweat spot. In China when they do this, when they find the sweet spot, they are doing this up against a wall with paper on it and they trace the curve of the batten. When I do it,
  11. Early winglets, probably 2015. It's a early WING rig, pre-cursor to the C8 (ILCA) rig. rig.
  12. There is a huge amount of air gong from the windward side of the main low down, spiralling down and around(the boom) and upwards on the leeward side of the main, even more so in a cat rigged boat. Huge vortex! There is that great bit of footage, some foiling Trimaran (Mantis, single handed) that has graced these pages where he let off a smoke flare and you can see the spiral. Prior to that, we did a series of tests to see how effective the cuff luff is, and we have tweaked its size so it’s just big enough 95% of the time. (If you really squeeze on main (49er) and don't bend the knees, you
  13. I actually think that's right, but it was initially Rob Mundel and John Diacopolous. I remember the first factory in Brookvale, and a Tasar arriving there (mid 70's) but I would have been very early teens (late 60's). So it could have easily started mid 60's.
  14. Just found the photo, you can see the winglets at the top, but I have no data on these rigs. I was in Rizhou for 49ers & FX, I did not even know 29erC's would be there. I think there where 8 of them. jB
  15. The short answer is yes they work. The justification for that answer is from the WING program and it acheiving a drag singnature which is not explainable other than from various drag reductions that things like the winglets afforded. Basically the boat performed better than prediction, and if you fold them down (and paper clip them flat) it performs "less well"! The initial ones where too big, and the parasidic drag was excessive. You also have to get the head agnle just so and it has to be intergrated with sail design, it's not a bolt on extra, it's more a intergreated drag re
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