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      Abbreviated rules   07/28/2017

      Underdawg did an excellent job of explaining the rules.  Here's the simplified version: Don't insinuate Pedo.  Warning and or timeout for a first offense.  PermaFlick for any subsequent offenses Don't out members.  See above for penalties.  Caveat:  if you have ever used your own real name or personal information here on the forums since, like, ever - it doesn't count and you are fair game. If you see spam posts, report it to the mods.  We do not hang out in every thread 24/7 If you see any of the above, report it to the mods by hitting the Report button in the offending post.   We do not take action for foul language, off-subject content, or abusive behavior unless it escalates to persistent stalking.  There may be times that we might warn someone or flick someone for something particularly egregious.  There is no standard, we will know it when we see it.  If you continually report things that do not fall into rules #1 or 2 above, you may very well get a timeout yourself for annoying the Mods with repeated whining.  Use your best judgement. Warnings, timeouts, suspensions and flicks are arbitrary and capricious.  Deal with it.  Welcome to anarchy.   If you are a newbie, there are unwritten rules to adhere to.  They will be explained to you soon enough.  

Hansen Aerosports

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  1. DC Designs

    The subject of winglets on sails comes up once in a while but IMHO, the highly specific geometric orientation required for a winglet is impossible given the variable heel, pitching and massively turbulent nature of wind. The only water-borne sailing vehicle without pitching is a windsurfer (with a universal joint) or possibly a hydrofoil craft like a Moth or Hydroptère but the the other variations remain. To drag around a winglet on the top of a sail which is likely only operating part of the time or under very limited conditions seems (to me) like a poor solution.
  2. DC Designs

    Baltic: Perhaps they do the same thing in a different way? Just saw this quote in a winglet article attributed to Dave Akiyama, manager of aerodynamics engineering in Boeing product development: "We find that it really doesn't matter what kind of wingtip device you use-they're all like span," he says. "The devil is in the details. Span extensions are the easiest and least risky."
  3. DC Designs

    In the mid-late '80's, a Naval Architect student at UC Berkeley did a CFD study on 'closing the gap' with a windsurfing rig and found significant gains in the last few cm's of gap closure with a 6.5sqm sail. Anyone who has windsurfed with performance equipment in marginal conditions has experienced this effect and found it dramatic. In post #47 by SlackWater_SF on 31 December 2005 - 10:33PM in this thread: http://forums.sailinganarchy.com/index.php?showtopic=27993&st=25 I found the following attributed to Tom Speer: Unfortunately, the above applies to una-rigs. My guess is it also applies to jibs but Tom could no doubt confirm and expound on the subject.
  4. DC Designs

    Andy: Looking good. Couple questions: Are those camber inducers connecting the battens to the mast? Does the mast rotate? Thanks!
  5. DC Designs

    Steve: I like it (not that it matters.) Max 10.6sqm including 1/2 spars - nothing above 6360mm. Simple, fair, plenty of room for innovation within the tradition of the IC. My 2¢...
  6. DC Designs

    Phil: I agree on the Moth. Moths are all about apparent wind which builds quickly when flying and they rarely run DDW. Not sure the IC is the same. Even though it is fast, the IC is stuck to the water and changes in wind velocity have a greater effect in overall pressure and direction. My guess is it is a matter of degree which means matching the compliance. Sounds like your rigs weren't optimally matched being too hard in one case and too soft in another. No doubt a tricky problem made worse by a UniRig...
  7. DC Designs

    Andy: I'm with you on the control mixing problem. Makes for a challenge in mast stiffness/bend and sail cut. Frustrating until you get it right and then rewarding. The 'springy effect' can be a benefit if the compliance of the rig matches the boat because it gives the sailor a chance to maintain balance. In variable conditions, the velocity squared force generated by building pressure initially overpowers the sailor and by the time he eases the sail and/or hikes out, the pressure is gone or he is capsized. In the real world, most sailors aren't capable of tweaking the strings and hiking out (or the reverse) quickly enough to maximize driving force. A compliant rig smears out and flattens the response automatically with a net gain in time-averaged drive. The problem is matching the compliance and that involves mast bend and sail cut again. Why don't you take the area away from the bottom and add it to the upper leech? I've found I can put a lot more up there than I ever thought at the start. Call it recut #4.5...
  8. DC Designs

    Judging from a look at a state-of-the-art El Toro, I'd have to agree. I probably misdirected my 'flame-bait' by mentioning strings instead of (on retrospect) jibs. Adjusting sail shape is even more critical on a UniRig and a more complicated engineering problem if it is unstayed because you get blended rather than independent adjustments. To me, that is the challenge. There will be strings. Let there be strings. Just no jib...
  9. DC Designs

    John and Phil: Lots of great info. Couple thoughts / reactions: First, my illustration is based on a Moth sail. The luff round shown is merely a remnant of that work based on an older, softer mast rather than a profile I would consider for an IC (or a Moth at this point.) The illustration was intended to create discussion on the UniRig and the replies are a testament to the level of enthusiasm for the IC. Clearly it is non-unique problem with multiple solutions which is why (to me) it is interesting. The intriguing part is in creating an optimal planform within the rules and ability of the sailor and engineering it to a level of viability. Second, I'll risk getting flamed soundly here but IMO one's level of sailing performance varies inversely with the level of complexity because there is more room to blame poor results on mis-trimmed sails, rigs, blades, etc. That's not to say that C Maas or Steve or the many other highly skilled IC sailors can't make a complex boat perform because clearly they do, only that they would have more time to concentrate and react to the wind and water without so many strings...
  10. DC Designs

    I checked the 2009 rule as found here: << http://www.canoeicf.com/site/canoeint/if/d...20-%20DRAFT.pdf. >> In my reading, no portion of the sail can be higher than 6360mm above the bottom of the boat and that is basically it. As such, I'd opt for a shorter unstayed mast (lighter, effectively stiffer, less drag) and moderately peaked head (at 6360mm) placed forward in the boat sufficient to keep the boom out of the way while preserving the square area. The weight saved in all the rigging, control lines and hardware of a sloop rig could be used to beef up the hull torsionally. Should make for a relatively simple, easy-to-sail boat with excellent downwind capability. What that hull might look like is a good project for the many talented folks here...
  11. DC Designs

    Gives you 10.4sqm...
  12. DC Designs

    I'll raise the clew if you let me make the boom longer. The rest isn't worthy of comment...
  13. DC Designs

    Can we sheet it in hard, pull on the strings and then measure? Too busy for another project or boat but will gladly help someone who isn't 'mess' with it a bit...
  14. DC Designs

    That is a very good question. From pictures I've seen, the 18' skiffs clearly don't have a problem with peaked heads being taller. Or, maybe they were illegal for class racing? Dunno. A similar sail(s) measured OK at the 2008 Moth Worlds. Later a question at the Moth US Nationals was raised without a clear answer but the fact the sails were approved at the Worlds seemed sufficient. One thing to consider is mast rake and tip bend underway and how it should be figured into the rule. This is particularly important to the Wyliecat 30 and now other unstayed boats in the SF Bay area who are having to deal with PHRF ratings. IMHO, the top of the sail should at least be parallel to the water when loaded. My preference as a sail designer is that it be slightly angled upward and I believe if the overall area is carefully measured and defined, overly peaking the head requires compromises elsewhere as well as engineering problems creating a self-regulating situation. Ultimately, the sail measurement rules will need to look at advances in technology and the idea of limiting headboards to right angles to limit the luff length (which is the original intent) need to be eliminated. Definitely an interesting development...
  15. DC Designs

    John: I had a brief look at the class rule WRT area and luff length. Upon further inspection, there could be other problems - not sure. The tube would depend on stayed or unstayed. I like unstayed rigs for their versatility downwind but that might be a structural problem on an IC. Thus, the Moth rig seems like a good place to start or perhaps a hybrid rig that is self-stayed to control/adjust bend but free to rotate... Phil: It may be too long at 5.75m. I arrived at 5.75 after seeing String Theory which was quite low at the deck. The design is very similar to the Moth sail where we learned some interesting things applicable in the future. Leech profile and shape variability are critical and putting a Unirig in an existing IC is problematic but perhaps doable (as you have shown.) My preference would be a unirig-specific or at least less sloop-specific hull such that the mast can be further forward. With that in mind, I think many of the other problems you mention like boom length, vangs and profile become tractable. A bit of a development project but certainly not beyond the capabilities of the people in this thread...