Little thread on Sailing Anarchy got me thinking about ventilation. I'm sure this is probably obvious to anyone who has watched the videos, but this is my take on the phenomenon.
Main foil sails through a small trough (wand wake, or just bad luck) and gets air onto the low part of the strut, which is rapidly immersed again, Whereupon ambient pressure goes WAY down from atmospheric, and then that little bit of air next to the foil just progressively expands to fill the entire low pressure region - PV-nRT? Air expands to fill the region of the foil where ambient pressure is lower than atmospheric - if it were higher than atmospheric then air bubble should not expand at all or "move". Amazing how much space air takes up when the pressure goes down.
That's my theory and I'm sticking with it. You need a way to get air onto a part of the foil that is normally continuously immersed - whether AOA sucking it down a vortex from the surface, or some sort of local temporary thing just putting it down there (e.g. hand of God). From there it just spreads like a turbocharged fungus.
I think putting fences on the leading edge is wrong. Bubble is always on the aft part of foil on the laminar flow sections and propagating down the concave part aft of max thickness. Rudder might be different story if you steer too hard at the wrong speed, but once established these foil farts all propagate the same way - down the trailing part of the foil, and onto the lifting foil if it gets that far, where the pressure is even lower...
Maybe (colder) more viscous water makes the pressure lower on aft part of foil. Seems like it might. Will have to try it out with a scale model and some maple syrup. And pancakes - no tow test is complete without pancakes and a wormhole or two.
Thursday, April 24, 2008
Friday, April 18, 2008
Naval Gazing
Trolling around YouTube waiting for the latest layer of epoxy to kick tonight I encountered an interesting video which recapitulates something I first considered several months ago with respect to Mothing, namely the degree to which the class has followed and will continue to follow an open- vs. closed-source information and development model.
When I first began following the class, I had no first-hand exposure to Moths, and this remained the case for seven or eight years until purchasing my first boat from abroad in early 2007. This remove allowed me to project all sorts of ideals onto the class which likely bore little resemblance to actual class practices, but seemed nonetheless attractive.
First and foremost was the notion that in this fleet, as opposed to nearly every other dinghy class on Earth, contributions from regular class members to the development of sailing boats
are encouraged and in fact formalized as a goal within the class rules. To wit:
Though obviously critical for any class with "development" aspirations, such a clearly-stated policy of promoting contributions from "users" of a technology to the development of that technology bears a strong resemblance to the open software movement, of which Linux seems the dominant example.
This "open-source" philosophy is essentially a value judgment on the part of the class, betting that the cumulative contributions of many talented designers and sailors will outperform, if you will, the efforts of any one organization in terms of moving Moth design forward over the long haul. It is also a powerful statement about the value and importance of development itself.
What we have seen recently with the success of Bladerider is in some ways a challenge to this thinking: a corporate entity with commercial interests designing a very competitive and innovative boat and investing heavily in making that boat perform better than its competitors, many of which predate the Bladerider. Some might argue that the Bladerider's success stems in large part (or entirely) from ideas and concepts borrowed from the common practices of the class, including the wand-driven flap, the tilting gantry rudder, and other now-common foiling moth features. Be that as it may, one must nonetheless acknowledge the technical ability which has gone into developing these systems beyond their previous levels of function, only to be copied again and employed by other amateur moth-builders in a kind of reflected wave.
Whatever the reason, the Bladerider has driven an expansion of Moth sailing into populations of sailors who previously seem to have steadfastly ignored the Moth. This "user" population comprises some stellar boathandlers and sailors who seem to have limited interest in the wholesale development aspect of the boat, preferring instead to take a known platform and work diligently to learn to extract the maximum speed from it. This growth has injected new vitality and enthusiasm into the class internationally and has facilitated modest fleet growth even in countries as dinghy averse as the US.
Patents are certainly a potential issue for the class. At least one Moth manufacturer has applied for patents on several of its boat's features. So the issue is real, and that reality invites the class to look collectively at it and take a position.
One might for instance require that all technology used on Moths be licensed to the class under the GPL or something equivalent. Exemptions could be created for commercially available blocks and other commonly used devices - or not, as simple non-patented substitutes are available for almost all current Moth hardware.
But this is hardly realistic: no company will work hard to develop ideas and test them if other builders can simply come along behind and reap the benefits without incurring any costs. At any rate they are unlikely to present a problem to an individual seeking to build a one-off copy of a commercial product, which is the most common objection raised against them. So patents are here to stay.
None of this would have made it onto this blog were it not for the following video, which jogged my memory by providing some examples (mountain biking etc.) of other technologies that have emerged through the user-level efforts of dedicated amateurs, following (in many cases unconsciously) open source models similar to what the Moth class has expressly promoted for decades.
When I first began following the class, I had no first-hand exposure to Moths, and this remained the case for seven or eight years until purchasing my first boat from abroad in early 2007. This remove allowed me to project all sorts of ideals onto the class which likely bore little resemblance to actual class practices, but seemed nonetheless attractive.
First and foremost was the notion that in this fleet, as opposed to nearly every other dinghy class on Earth, contributions from regular class members to the development of sailing boats
are encouraged and in fact formalized as a goal within the class rules. To wit:
The intention of these class rules is to give the designer and builder the fullest liberty in design and construction, within these rules to develop and produce faster boats.
Though obviously critical for any class with "development" aspirations, such a clearly-stated policy of promoting contributions from "users" of a technology to the development of that technology bears a strong resemblance to the open software movement, of which Linux seems the dominant example.
This "open-source" philosophy is essentially a value judgment on the part of the class, betting that the cumulative contributions of many talented designers and sailors will outperform, if you will, the efforts of any one organization in terms of moving Moth design forward over the long haul. It is also a powerful statement about the value and importance of development itself.
What we have seen recently with the success of Bladerider is in some ways a challenge to this thinking: a corporate entity with commercial interests designing a very competitive and innovative boat and investing heavily in making that boat perform better than its competitors, many of which predate the Bladerider. Some might argue that the Bladerider's success stems in large part (or entirely) from ideas and concepts borrowed from the common practices of the class, including the wand-driven flap, the tilting gantry rudder, and other now-common foiling moth features. Be that as it may, one must nonetheless acknowledge the technical ability which has gone into developing these systems beyond their previous levels of function, only to be copied again and employed by other amateur moth-builders in a kind of reflected wave.
Whatever the reason, the Bladerider has driven an expansion of Moth sailing into populations of sailors who previously seem to have steadfastly ignored the Moth. This "user" population comprises some stellar boathandlers and sailors who seem to have limited interest in the wholesale development aspect of the boat, preferring instead to take a known platform and work diligently to learn to extract the maximum speed from it. This growth has injected new vitality and enthusiasm into the class internationally and has facilitated modest fleet growth even in countries as dinghy averse as the US.
Patents are certainly a potential issue for the class. At least one Moth manufacturer has applied for patents on several of its boat's features. So the issue is real, and that reality invites the class to look collectively at it and take a position.
One might for instance require that all technology used on Moths be licensed to the class under the GPL or something equivalent. Exemptions could be created for commercially available blocks and other commonly used devices - or not, as simple non-patented substitutes are available for almost all current Moth hardware.
But this is hardly realistic: no company will work hard to develop ideas and test them if other builders can simply come along behind and reap the benefits without incurring any costs. At any rate they are unlikely to present a problem to an individual seeking to build a one-off copy of a commercial product, which is the most common objection raised against them. So patents are here to stay.
None of this would have made it onto this blog were it not for the following video, which jogged my memory by providing some examples (mountain biking etc.) of other technologies that have emerged through the user-level efforts of dedicated amateurs, following (in many cases unconsciously) open source models similar to what the Moth class has expressly promoted for decades.
Sunday, April 13, 2008
The Moth of Narcissus
Perusing a personals advert from a comely young lass recently, it occurred to me that the reason she needed a personal ad was that she didn't have TIME for a boyfriend. Between her triathalons, incessant tourist vacations to exotic lands, work, and non-stop swimming-running-biking during the week, a guy would have to be a triathelete to spend any time with her. "He needs to be someone who can keep up with me" the ad went on, "someone with a brain, not a couch potato, who is creative and interested in learning new things".
Well, I have news for you sweetheart: all those guys are just as self absorbed as you are. What they need is someone who isn't trying to win triathalons, someone who is into, well, stuff that doesn't compete as much with what they are doing. It isn't that one shouldn't want to be a triathelete; it's only that if you are one then maybe a couch potato is precisely what the doctor ordered: to cook your high-starch meals, iron your skimpy lycra suits, and drag your tired ass and all your equipment around the country to your meets while holding down a job so you can focus on your sport. After all, the last thing a narcissist needs in a mate is another narcissist.
So when I see ads like that, I wonder: is modern singles society just a bunch of narcissistic, nutrition-obsessed, neurotic exercise freaks talking past each other? And is this why so many single people are out there in their mid to late 30s - ages when women were once considered old maids, and men confirmed bachelors?
If so, it's not looking good for yours truly. Work, sailing and building are crowding all those would-be evenings out, well, out.
Breeze came late to Long Beach today, catching me at my computer. So it was a mad dash to drag the Moth out from beneath its rubber tree camouflage and rock on down to the beach. Only the beach today was different: all winter long I have been wondering why I am the only one on the beach when I go sailing, and the answer is that Californians don't consider it a good beachgoing day unless it is over 80 and sunny. So the beach was packed with people, the water was an interesting shade of stinky, and had lots of grass floating in the surf. The wind was dying already around 3:30 when I launched but out beyond the breakwater it held on for a good long time and I had some nice gybing runs down behind various cruising boats who must think I am completely mad - gybing every 30 seconds or so, making it most of the time but occasionally screwing something up enough to capsize. As the breeze moderated I wasn't even going downwind very fast in this mode - just getting up to speed on a reach before pointing it down and going for it yet again. At first I was depressed as they seemed to have gone better last weekend, but by the end of the day I had regained the lost ground and even began to appreciate new subtleties of the gybe.
Then the wind shut off and I had a very slow sail back to shore, where couples feuded in the parking lot and various children attempted to commit suicide by running full tilt out onto Ocean Boulevard faster than their fat, inattentive parents could catch them up - but not for lack of screaming. One thing drunk, beachgoing Californians seem to do very well is shout completely trivial or private information at each other loud enough to make you wonder if there is some emergency at hand. It makes the occasional "stop you little shit or you'll get run over by a car" seem halfway normal even.
So in my ripe old age I am beginning to appreciate why yacht clubs were formed in the first place. They may have their issues, but at least one does not have to kick bags of half-eaten fast food out of the way to put one's boat on the trailer in the parking lot.
Well, I have news for you sweetheart: all those guys are just as self absorbed as you are. What they need is someone who isn't trying to win triathalons, someone who is into, well, stuff that doesn't compete as much with what they are doing. It isn't that one shouldn't want to be a triathelete; it's only that if you are one then maybe a couch potato is precisely what the doctor ordered: to cook your high-starch meals, iron your skimpy lycra suits, and drag your tired ass and all your equipment around the country to your meets while holding down a job so you can focus on your sport. After all, the last thing a narcissist needs in a mate is another narcissist.
So when I see ads like that, I wonder: is modern singles society just a bunch of narcissistic, nutrition-obsessed, neurotic exercise freaks talking past each other? And is this why so many single people are out there in their mid to late 30s - ages when women were once considered old maids, and men confirmed bachelors?
If so, it's not looking good for yours truly. Work, sailing and building are crowding all those would-be evenings out, well, out.
Breeze came late to Long Beach today, catching me at my computer. So it was a mad dash to drag the Moth out from beneath its rubber tree camouflage and rock on down to the beach. Only the beach today was different: all winter long I have been wondering why I am the only one on the beach when I go sailing, and the answer is that Californians don't consider it a good beachgoing day unless it is over 80 and sunny. So the beach was packed with people, the water was an interesting shade of stinky, and had lots of grass floating in the surf. The wind was dying already around 3:30 when I launched but out beyond the breakwater it held on for a good long time and I had some nice gybing runs down behind various cruising boats who must think I am completely mad - gybing every 30 seconds or so, making it most of the time but occasionally screwing something up enough to capsize. As the breeze moderated I wasn't even going downwind very fast in this mode - just getting up to speed on a reach before pointing it down and going for it yet again. At first I was depressed as they seemed to have gone better last weekend, but by the end of the day I had regained the lost ground and even began to appreciate new subtleties of the gybe.
Then the wind shut off and I had a very slow sail back to shore, where couples feuded in the parking lot and various children attempted to commit suicide by running full tilt out onto Ocean Boulevard faster than their fat, inattentive parents could catch them up - but not for lack of screaming. One thing drunk, beachgoing Californians seem to do very well is shout completely trivial or private information at each other loud enough to make you wonder if there is some emergency at hand. It makes the occasional "stop you little shit or you'll get run over by a car" seem halfway normal even.
So in my ripe old age I am beginning to appreciate why yacht clubs were formed in the first place. They may have their issues, but at least one does not have to kick bags of half-eaten fast food out of the way to put one's boat on the trailer in the parking lot.
Friday, April 11, 2008
Two very interesting videos posted recently.
First is Rohan's footage of himself sailing downwind in breeze at Garda. Really nice clips. Good to know that really good sailors look really ugly going downhill in that crap too, except his gybes, which are fantastic. If you've tried it, your heart starts to beat faster just watching. And it isn't the music:
Second is JPZ posting two vids with spectacular real-time footage of a Prowler rudder ventilating under pretty ordinary circumstances. It appears the section is pretty much always ventilating a little bit, and when the lifting foil is close enough to the surface this propagates and stalls both foils. In the second video the tip clearly hits the surface though. First time I have seen so many examples on one clip. Rock on JPZ! (Who IS this guy anyway?)
First is Rohan's footage of himself sailing downwind in breeze at Garda. Really nice clips. Good to know that really good sailors look really ugly going downhill in that crap too, except his gybes, which are fantastic. If you've tried it, your heart starts to beat faster just watching. And it isn't the music:
Second is JPZ posting two vids with spectacular real-time footage of a Prowler rudder ventilating under pretty ordinary circumstances. It appears the section is pretty much always ventilating a little bit, and when the lifting foil is close enough to the surface this propagates and stalls both foils. In the second video the tip clearly hits the surface though. First time I have seen so many examples on one clip. Rock on JPZ! (Who IS this guy anyway?)
Sunday, April 6, 2008
Smooth Sailing
I was thinking recently about a perfect Moth day, in the best of all possible worlds. What I came up with was get up after a good night's sleep, eat something, stumble out to laundry room en route to garage, grab coverall and don in ambulatory fashion, kick on some clogs, mix a bit of goo and glom the bottom of a hydrofoil on using obligatory "every clamp in the joint" technique, throw sailing stuff in truck, hook boat up, drive to Long Beach for a sail where there is a steady 10-15 from the southwest. Sail for a few hours, ideally in close enough proximity to other fleets of racing dinghies that they can appreciate what they are missing. Practice tacking and gybing in the flatwater lee of a long seawall all afternoon. Make progress, feel reasonably in tune with the boat, have something click in your boathandling so that gybing no longer seems impossible and is in fact borderline predictable. Go in, derig, fix a few things, change, stop by the club to snarf a few Hors d'ouerves, and drive home, stopping en route to pick up stranded, post-collegiate, cute but ditzy in that narcissistic "I'm out of college and I don't know what to do with my life, so I'm hitchhiking around the country instead of getting a job" way American hitchhiking backpackers from Mini Mart in Compton and buy diesel for $4.19 a gallon. Come home, crack the foil out of the mold, put it in a heat box with a controller to post-cure for eight hours at 135F, put some pasta on the stove, and eat it while blogging a bit about the day's events. Now what's not to like about a day like that? Sort of isolating, all this foiling, but at least I saw Charlie and Hans out on the water and had a chance to say hello. Owe Charlie a big one for reminding me to replace the tiller centering bungee I so foolishly removed at Coronado. Big mistake, that. Makes a HUGE difference coming out of the gybes.
Have to echo Mr Dubai moth guy when he says "I LOVE SAILING MOTHS". You have to earn a Moth's love, which is notoriously fickle and can waver at the slightest unexpected ferry wake. But when it's going well, it's REALLY going well. Even surfed a powerboat wake upwind for half a mile today - that was a first on foils. Just sort of bizarre to be sailing twenty yards off their stern for that long.
The sailing shoes have sailed their last. Time to bust out a new pair from the archive - too bad they no longer make the Lotus kayaking water shoe as it is possibly the greatest sailing shoe ever, apart from the Converse Chuck Taylor.
That's about it. Going back to centerline sheeting, after monkeying around with boom sheeting for months, which I adopted rather accidentally. Just better to have it somewhere predictable when everything is heading South.
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