Page 2 of 3 FirstFirst 123 LastLast
Results 36 to 70 of 105

Thread: Which naca profiles for sailingboats

  1. #36
    Join Date
    May 2005
    Location
    Central PA
    Posts
    2,968

    Default Re: Which naca profiles for sailingboats

    Quote Originally Posted by keyhavenpotterer View Post
    A NACA foil is efficient, but its more efficient to choose a good boat design, a high aspect rig, rigging controls and flatter cut sails if you want to go upwind well.
    By pure symmetry, it's pretty much arbitrary whether you think of the wind as pushing the boat through the water, or the water as pushing the boat through the air. That little centerboard, only 4% the size of all the sails (or so) is doing exactly the equal amount of effort! Minus that which is attributable to the hull, of course.

    They both deserve equal attention to detail, in short.
    It will all be OK in the end...so if it's not OK, you're not at the end.

  2. #37
    Join Date
    Nov 2007
    Posts
    4,992

    Default Re: Which naca profiles for sailingboats

    Quote Originally Posted by Y Bar Ranch View Post
    They both deserve equal attention to detail, in short.
    I'm just not sure they do.

    Our 150kg 17ft Oughtred Tirrik gunter sloop dinghy goes upwind at 30-40 degrees off the wind in a Force 2 with two people in it, with a thin 6mm wide flat high aspect Oughtred planform metal steel centreboard with little appreciable leeway with good speed powered by new professionally made sails:a bermudan main and jib. I know its contrary to what the text books would say. I've read them too. But that's the reality and an honest observation. It's left me thinking foiling centreboards might be a bit of a waste of time, as thin flat centreplates seem to be able to achieve perfectly good performance in actuality, if everything else is right, and its no work. I was very surprised. Boat turns fine too, doesn't stall. Before the Tirrik, I would have been equally dissmissive, but not now. I'll leave it at that.

    Ed
    Last edited by keyhavenpotterer; 04-10-2012 at 05:35 PM.

  3. #38

    Default Re: Which naca profiles for sailingboats

    There may be lots more unknowns than is generally recognized. Boat design seems to me an inherently conservative preoccupation, in the sense that few designers are willing to diverge wildly from the work their peers are doing. Longtime members here may recall that I caught a lot of crap for putting a sprit-sloop rig on my little cat, because, the experts said, it wouldn't point and it wouldn't be fast.

    Neither turned out to be true. The boat is very conservatively rigged, with 140 sq feet of sail, and as a cruising boat, is much heavier than beach cats with the same length and beam and well over 200 sq. feet of sail, so I didn't expect beach cat performance. Naturally, I didn't get it. But it has been surprising to me that to windward at least, the boat points higher and goes faster than Windrider 17s, the little rotomolded plastic tris that are a hoot to sail. The Windriders have almost exactly the same amount of sail in a high-tech, fully battened main and fractional jib, but instead of a daggerboard, they have a molded in minikeel. They weigh substantially less than Slider as well.

    Anyway, it's at least another datapoint in support of the idea that foils (and hull shapes) are equal in importance to rigs and sails.

  4. #39
    Join Date
    Jan 2007
    Location
    North Shore, Massachusetts
    Posts
    5,919

    Default Re: Which naca profiles for sailingboats

    Quote Originally Posted by keyhavenpotterer View Post
    NACA foil is low down the list of importance to how your chosen transport goes upwind.
    "hit the nail on the head"

    thats exactly what I was trying to say (in many more words) in post #5

  5. #40
    Join Date
    Jun 2002
    Location
    San Pedro, CA
    Posts
    737

    Default Re: Which naca profiles for sailingboats

    "Hit no nail on the head"... and wandered around the landscape making comparisons that hold little connective tissue, calling them valid points in a disconnected argument. The, "Our Tirrik sloop with a metal plate and new sails, outpoints a 420 with a Milanes centreboard (very expensive profiled blade) with old sails....". I'm fascinated that a displacement sloop of the variety called-out and a trapeze rigged planing craft, such as the 420, are even mentioned in the same breath, much less compared on any level. That the argument is so drifty to include the admission regarding state of sail condition, and still goes on to use the event to justify a barely worked metal keel form, is less than well-founded. If there is a nail in that jumble, it's invisible... as is the hammer used to strike it.

    What is absolutely remarkable here in all this flat plater stuff, is the nearly complete disregard for all the research done on section lift, drag buckets, Reynolds numbers, foils as tested over the years by countless tank sessions for the AC, as well as other racing classes... and the critical study work of thousands of Naval Architects since day one on this topic. Let's just toss that whole body of work in the bin and instead opt for the no-tech answer when all the science has long been done for you and it's easy to replicate with a modicum of toilage and skill. Something saddens me when I see these kinds of discussions and there is a cadre of flat platers, for instance, who are adamant about their low wattage solutions. These are the same folks, mind you, who will diddle around with one knot, or another, for a given task, or how many coats of varnish are needed to seal a soft wood core from water entry, or, who is going to build their retro sail kit and with what cloth will it be made, or which seat thwart arrangement is going to give them that saltier than thou look when they arrive at the ramp. It would be sad if it weren't so amusing.

    And Ray, I think that you will find that the designers aren't conservative at all. One look at their private portfolios will show you the facts in the matter. The conservatism is in the end user who tells the NA what kind of boat he wants and that's where the snappy fresh ideas get rubbed right off the page. If one wants to advance the craft with fresh big stick ideas, it is best to approach this kind of consumer by bending them into the fold, so to speak, one increment at a time. Large leaps do not make for excited buyers. The tire kickers will be salivating to death over a bitchin’ cutting edge ride, but they aren't the ones who actually snatch-up the plan sets.

  6. #41
    Join Date
    Oct 2009
    Location
    Juneau, Alaska
    Posts
    3,813

    Default Re: Which naca profiles for sailingboats

    This has been an interesting discussion. I had an inappropriately made mostly flat center board that cupped so badly it was hard to raise and lower. As a result my Caledonia Yawl pointed noticeably better on one tack. I made a nicely shaped board sheathed in a layer of glass and epoxy to replace it after reading a little about foils and I was amazed at the difference it made. I'm not sure where that puts me in this discussion, but I am definitely a believer in devoting some attention to the shape of center boards.

    Jim
    -Jim

    Sucker for a pretty face.
    1934 27' Blanchard Cuiser ~ Amazon, Ex. Emalu
    19'6" Caledonia Yawl ~ Sparrow

    Getting into trouble one board at a time.

  7. #42
    Join Date
    Mar 2011
    Location
    Scotland
    Posts
    1,314

    Default Re: Which naca profiles for sailingboats

    ...some attention, yes. But I'd argue that the rudder's the first thing we should think about optimising: this plate needs to be angled to the direction of travel, without stalling for as long as possible, in order to do its job.

    The centreboard is fixed to the long axis of the hull. Does it ever operate at angles of attack above a few degrees? Always in a low-speed regimine? Flat plates work ok in certain circumstances.

    Andy
    "We were schooner-rigged and rakish, with a long and lissome hull ..."

  8. #43
    Join Date
    Aug 2006
    Location
    Rockford, IL
    Posts
    8,055

    Default Re: Which naca profiles for sailingboats

    Keep in mind that the leaders in assymetric "lifting" foils use them on the most "conservatively designed" types boats extant, the Dutch Botters and similar gaff-rigged, bluff-bowed, extreemly massive, shallow draft ilk.

  9. #44
    Join Date
    May 2005
    Location
    Central PA
    Posts
    2,968

    Default Re: Which naca profiles for sailingboats

    This is a cool little web app. Obviously not to be used for design! Didn't check the reynolds number ranges, but you can compare L/D for different shapes to include flat plate and something that ia probably close to NACA 0012. The flat plate is idealized, of zero thickness.

    http://www.grc.nasa.gov/WWW/K-12/airplane/foil3.html
    It will all be OK in the end...so if it's not OK, you're not at the end.

  10. #45
    Join Date
    Apr 2007
    Location
    Singapore
    Posts
    11,621

    Default Re: Which naca profiles for sailingboats

    A lot of this is not very rigorous armchair theorizing, gentlemen. Comparing one boat with another, different boat is not all that useful in figuring out this question because you haven't limited and isolated all the variables. The correct experiment is to test two boats that are otherwise identical except for the foil, or to test one boat where you first install one type and then test again with another type installed.

    I have actually done this sort of experiment with a leeboard versus a daggerboard in both a Bolger Teal and a Chamberlain Dory Skiff, and I have done another experiment with a flat plate centerboard with rounded edges versus a carefully shaped foil in a Ness Yawl.

    When I built Rowan a few years ago, the culmination of 41 previous false starts, approximations and accumulated boating and boatbuilding experience, I most definitely did not settle for either a leeboard or a flat plate. I agree with jsjpd1 and think a properly shaped foil is totally worth the effort.
    Last edited by James McMullen; 04-11-2012 at 08:10 AM.

  11. #46
    Join Date
    Aug 2006
    Location
    Rockford, IL
    Posts
    8,055

    Default Re: Which naca profiles for sailingboats

    As did I, James McMullen, sailing my Shearwarter Yawl TRUE NORTH sailing abreast of another Shearwater Cat Yawl, ARDEA. I sailed my boat in company with the ARDEA in circumstances both with, and without "lifting" foil leeboards. The results clearly favor assymetric "lifting" foils. The only significant difference between boats was my Yawl rig (an Edey & Duff experiment) against the other's Cat Yawl rig (as designed my Bolger). The total sail areas were comparable.

  12. #47
    Join Date
    Aug 2010
    Location
    Southern NH
    Posts
    1,334

    Default Re: Which naca profiles for sailingboats

    Sailing in a straight line at or close to hull speed with a well balanced rig, any reasonable sized fin will do fine, flat plate or elegant foil. the fins, whatever their shape, are generating all the lift required. Where a good foil shape is important is at lower speeds and higher angles of attack, especially if the foils are undersized. I turned a dog of a boat into a decent sailor by making a slightly larger daggerboard with as good a foil shape as I could get in the narrow slot. I've been frustrated enough by centerboards and/or rudders stalling at inopportune moments to be firm believer in the value of a well shaped foil.

    Allan

  13. #48
    Join Date
    Aug 2006
    Location
    Rockford, IL
    Posts
    8,055

    Default Re: Which naca profiles for sailingboats

    At something less than hull speed in a force 2 wind the difference in VMG between my boat and the ARDEA was something like 10-degrees, and I was significantly slower.

  14. #49
    Join Date
    Nov 2007
    Posts
    4,992

    Default Re: Which naca profiles for sailingboats

    James,

    By choosing a low aspect lug rig, you've lost more to windward than my high aspect bermudan and choosing a flat plate.

    My Tirrik will outpoint Rowan by 10 degrees. The flat plate is ZERO work. In a race to windward I'd beat you by some distance.

    My boat will take fewer hours to build.

    The three spars of a gunter are the same length as a lug. You just say bermudan main and jib to the sailmaker not lug. No work there either.

    My choice is more efficient to windward than yours in absolute terms and in speed to windward per man hours invested. I might be 3% less efficient than if I had a NACA foil, but I'll still be outpointing you to windward because of your rig choice.

    I'll only be worse off if I meet another sloop rig Tirrik, built, rigged and crewed like mine, with a NACA board and we're going upwind, racing and in close proximity. Then his NACA board would come into play and he theoretically might outpoint me.

    A low aspect sail plan looses far more to windward than using a flat plate. Your CNC NACA centeboard might be optimum to windward but your low aspect rig isn't. There's a reason low aspect sail plans were dropped overnight when bermudan's came along...sail planform and adjustment is a much more important variable.

    Really, as I've found out, don't snigger at someones metal plate next time your on a beach looking at boats, because if he's got a bermudan, and your in a lug or gaff, he'll still outpoint you, no matter what foil you've got. An uncomfortable truth I know. NACA away boys!

    Ed
    Last edited by keyhavenpotterer; 04-11-2012 at 10:37 AM.

  15. #50
    Join Date
    Nov 2008
    Location
    Schleswig Holstein Germany
    Posts
    456

    Default Re: Which naca profiles for sailingboats

    Is it really only to windward when a foil comes to work ?
    What about a beam reach?
    The conversation gets a little hot tempered Gentlemen ;-).
    Sure, many factors come into play to get a craft sailing fast and comfortable.
    And I guess all of us know that.
    I would prefere to keep the focus on foils isolated.
    cheers
    Max

  16. #51
    Join Date
    Jan 2010
    Location
    Sweden,Scilly Isles, Siberia
    Posts
    7,476

    Default Re: Which naca profiles for sailingboats

    Always a lively debate. I will agree there is a potential performance increase in the use of NACA foils, but im also on the side of simplicity. Flat metal plates work as leeway prevention,but not as efficient as a NACA foil. As Ed has pointed out, rig and sails can make more of a difference to windward performance than plate alone,as can all the other aspects of hull shape,crew ability etc etc ad nausism. I have just made a set of foils,rudder and daggerboard for a dayboat,theres about 30% flat sides and the rest is tapered,thicker at the nose and shallow angle all the way to the back square edge. Took about 2 hours to do both with an electric plane and a disc sander. Im guessing it wont stall as soon as a flat plate, but it also wont have as much lift as a true NACA foil, but as its going in my own dayboat with a balanced lug rig i was not prepared to spend the extra hours creating a true foil. That does not mean i dont respect the years of work gone into foil research,but as an owner/builder,its up to me to decide on what i think is performance worthy in terms of time invested.
    Another project will have a 0012 drop keel and a 0009 rudder section,but that project will be built as a performance boat. Cheers

  17. #52
    Join Date
    Apr 2007
    Location
    Singapore
    Posts
    11,621

    Default Re: Which naca profiles for sailingboats

    Quote Originally Posted by keyhavenpotterer View Post
    James,

    By choosing a low aspect lug rig, you've lost more to windward than my high aspect bermudan and choosing a flat plate.

    My Tirrik will outpoint Rowan by 10 degrees.
    Ed, I think you're totally exaggerating. I haven't sailed with a sloop-rigged Tirrik any time I can remember, but I've sailed in company with all sorts of sloop-rigged boats and I don't get particularly outpointed by any that aren't something like an Etchells or a Melges. 10 degrees is huge! And I don't just always sail in lapstrake character rowboats either, I ride the trapeze on a 505 or drive an eight-ton 36' yawl on occasion too, so I'm not just a single rig partisan. Rowan's got a high peaked and pretty high aspect lug foresail, and she points awfully good for a rowboat. I credit the foil for much of that.

    I choose the lug rig for a sail and oar boat for a great many reasons--particularly handling and handiness--but that doesn't mean I don't enjoy wringing all the performance I can out of this boat. I am never content with low-performing boats of any shape or sort, be they paddled or rowed or sailed. Since tank testing has proven that a properly shaped foil will provide better performance than a flat plate, I think it's very much worthwhile to add it into the mix of all the other compromises and choices you have to make when chasing down an optimax solution for my own particular variety of boating.

    I don't expect anyone to take my claims on faith or purely as an academic thought experiment. Rowan and I will be at Howard Rice's Small Boat show in Port Townsend on May 19 and again at the PT Wooden Boat Festival In September for any of you relatively local guys who would like an easy opportunity to check her out.
    Last edited by James McMullen; 04-11-2012 at 03:16 PM.

  18. #53
    Join Date
    Jul 2003
    Location
    South Bristol, Maine
    Posts
    204

    Default Re: Which naca profiles for sailingboats

    Here's what little I can contribute from an engineering point of view:

    A typical flat plate will generate lift up to an angle of ~6 degrees depending on aspect ratio and other factors, then it will stall and give high drag. A NACA 0010 foil will go to ~12 degrees before it stalls, and an asymmetric foil will go to about 18 degrees. These numbers are for comparison purposes only, not hard and fast values.

    To visualise why a flat plate will stall early, consider that there is a component of flow that travels from the high pressure region under the foil, up across the nose (leading edge) of the foil to the low pressure region above it. The thicker the foil, the easier it is for this flow component to travel across the front edge of the foil without separating. This is why NACA type foils are not sharp at the leading edge, and why thicker foils stall at a higher angle of incidence.

    If the boat in question is set up with a moderate amount of weather helm, a flat plate center/ dagger/ leeboard often may not see more angle than it takes to stall it, assuming it is making a reasonable speed. The rudder, however, will be operating at a much higher slip angle as it works to counter the sails' attempts to make the boat round up into the wind, and will therefore generate most of the lift to windward. The rudder therefore should have a thicker chord than the board.

    In terms of finish and profile accuracy, invest most of your time on the front 1/3 of the foil, since flow will inevitably become turbulent and separated as it passes along the surface.
    Last edited by Geoff C; 04-13-2012 at 08:22 AM.
    Or who shut up the sea with doors, when it brake forth, as if it had issued out of the womb?
    When I made the cloud the garment thereof, and thick darkness a swaddlingband for it,
    And brake up for it my decreed place, and set bars and doors,
    And said, Hitherto shalt thou come, but no further: and here shall thy proud waves be stayed?
    Job 38: 8-11

  19. #54
    Join Date
    Oct 2010
    Location
    Queenstown, NewZealand
    Posts
    307

    Default Re: Which naca profiles for sailingboats

    Quote Originally Posted by AndyG View Post
    My problem with the NACA-knows-best school of thought is based on where those foils come from.

    NACA designed aerofoils (up to the 50s) for a medium which is compressible and of a very different density and viscosity to water. Wing designs for high-speed flight in a powered aircraft in more-or-less stable air would suggest that slavishly copying designs for low-speed sailing in choppy and moving water, each operating at quite different Reynold's numbers, are not optimal...

    Andy
    The NACA 00XX series was figured out a long time ago (1930's) when aeroplanes were small and slow. Airfoil deign has come a long way since then, but those old sections for small slow aeroplanes are in the range of Reynolds numbers for sailing boat foils, hence their widespread use.

    Neil Pollock produced a foil section which is parallel sided with shaping on the leading and trailing edges that is much easier to shape than a naca section and very nearly as good. It saves the issues of tapering the thickness as the chord reduces towards the tip of the foil - thickness can stay the same, just the parallel sided section between the leading and trailing edge shaped sections is smaller. Here is a reference to the formula for calculating it: http://www.boat-links.com/foils.html (scroll down to section 2.3 Parallel Sided Foils)

    Michael Storer uses these Pollock parallel sided foils, you could get the template by spending $20 on his OZ racer plans.

    I've seen some research (by Frank Bethwaite, I think) referred to that compared foils shaped leading and trailing edge by hand and eye versus shaping by hand with the aid of good templates, all other things kept equal. I recall a measurable difference around a race course of perhaps 5%. Perhaps someone has a reference to this research?

    Ian

  20. #55
    Join Date
    Jan 2004
    Location
    Norwich,United Kingdom
    Posts
    4,651

    Default Re: Which naca profiles for sailingboats

    [QUOTE



    I've seen some research (by Frank Bethwaite, I think) referred to that compared foils shaped leading and trailing edge by hand and eye versus shaping by hand with the aid of good templates, all other things kept equal. I recall a measurable difference around a race course of perhaps 5%. Perhaps someone has a reference to this research?

    Ian[/QUOTE]

    I have seen many races in which the difference between placing well or not so well was half the length of a foredeck after 90 minutes racing.A 5% performance gain of just one element of the boat would be well worth having.Those with the willingness to learn how to use the free Xfoil program can develop their own foils.It takes a bit longer to learn to make those foils unless you have access to a CNC router.

  21. #56
    Join Date
    Aug 2000
    Location
    Auckland ,N.Z.
    Posts
    23,351

    Default Re: Which naca profiles for sailingboats

    Foils are pretty. Its like looking at the front guard of an xk120.
    Don't you just love lying down in the boatyard starin up at those lovely rudder profiles
    ... or, is it just me.

  22. #57
    Join Date
    Jan 2007
    Location
    North Shore, Massachusetts
    Posts
    5,919

    Default Re: Which naca profiles for sailingboats

    Ian[/QUOTE]

    I have seen many races in which the difference between placing well or not so well was half the length of a foredeck after 90 minutes racing.A 5% performance gain of just one element of the boat would be well worth having.Those with the willingness to learn how to use the free Xfoil program can develop their own foils.It takes a bit longer to learn to make those foils unless you have access to a CNC router.[/QUOTE]




    Quote Originally Posted by John B View Post
    Foils are pretty. Its like looking at the front guard of an xk120.
    Don't you just love lying down in the boatyard starin up at those lovely rudder profiles
    ... or, is it just me.
    the above are two excelent reasons to insist on precisely shaped NACA type foils for your sail boat...
    1: You are involved in high stakes, cut throat, international calibre competition at the highest levels where a boat lenght of speed over many miles traveled is important.
    2: Foils make you feel good about your boat.

    I am someone who is a big fan of excelent performance, heck I take the extra 3 munites at the ramp to hook up a stay set because I find the lightness and stiffness of a stayed rig increases boat speed considerably. When designing the Ipswich Bay 18 I went with a Aluminum plate centerboard and a foil shaped rudder.

    I have discussed the merits of foil vs. plate type boards with my father a ME grad of MIT and fuel controlls engineer for jet engines for 30+ yrs, he has also designed and built his own hover car and utility class racing boats, this is a guy who knows fluid flow in all it's intracicies and he has greatly informed my understanding of the subject.

  23. #58
    Join Date
    Jan 2010
    Location
    Sweden,Scilly Isles, Siberia
    Posts
    7,476

    Default Re: Which naca profiles for sailingboats

    Im curious to know why James used the same NACA 0012 section for the board and rudder foil? Is your rudder somehow constrained to swing through a small arc that this profile wont stall? Cheers

  24. #59
    Join Date
    Apr 2007
    Location
    Singapore
    Posts
    11,621

    Default Re: Which naca profiles for sailingboats

    Well, I was assured by my computer programmer friend that 0012 was the ne plus ultra and Holy Grail of all small boat foils, and besides, he already had the algorithm plugged into the CNC. Plus, there is such a thing as putting too fine a point on something. It's just a freakin' rowboat after all.

  25. #60
    Join Date
    Aug 2006
    Location
    Rockford, IL
    Posts
    8,055

    Default Re: Which naca profiles for sailingboats

    The thicker the foil cross-section, the higher the number; 0012 is thicker than 0009, and the thicker section is more resistant to stall.

  26. #61
    Join Date
    May 2005
    Location
    St. Augustine, FL
    Posts
    3,373

    Default Re: Which naca profiles for sailingboats

    Quote Originally Posted by James McMullen View Post
    ...It's just a freakin' rowboat after all.
    Did you get hit by lightning or something??? Do you have a fever? Did you recently fall and hit your head? Whatever it was that caused you to make such a rash statement, I hope you overcome it and get back to your old self again soon. Who the heck am I going to argue with if you go mainstream on us???

  27. #62
    Join Date
    Feb 2007
    Location
    Waterbury, Connecticut
    Posts
    1,906

    Default Re: Which naca profiles for sailingboats

    Is there a good site from which you can print out foil shapes for use as templates? --Wade

  28. #63

    Default Re: Which naca profiles for sailingboats

    Wade, if you look around on Duckworks, there's a spreadsheet that allows you to plot and print out a profile of the 4-digit NACA foils.

    Another possibility is to buy a model aircraft wing blank of foam then reinforce and glass it. That's what I did for a centerboard for my little cartop cat. The foam is just crappy styrofoam beadboard stuff, but the shape is extremely precise, and the blanks are pretty cheap. I got 2 wings, about 12 inches by 36 inches 0012 for less than 40 bucks. I just glassed the blank to a plywood piece that the pin went through, but you could probably make them adequately strong for general use by milling a couple of slots into them and filling the slots with carbon tow, then bagging the glass onto the blank.

  29. #64
    Join Date
    Aug 2006
    Location
    Rockford, IL
    Posts
    8,055

    Default Re: Which naca profiles for sailingboats

    Thanks for the ip on Styrofoam Wings, slidercat! I may try one on a boat sometime.

    ONE CAUTION, FOLKS!!! Styrofoam can be sheathed in EPOXY RESIN and fiberglass, BUT NOT POLYESTER RESIN. Polyester will disolve Styrofoam.

  30. #65
    Join Date
    Feb 2007
    Location
    Waterbury, Connecticut
    Posts
    1,906

    Default Re: Which naca profiles for sailingboats

    Very interesting, Ray, thanks. -- Wade

  31. #66
    Join Date
    Jun 2002
    Location
    San Pedro, CA
    Posts
    737

    Default Re: Which naca profiles for sailingboats

    Quote Originally Posted by Daniel Noyes View Post


    the above are two excelent reasons to insist on precisely shaped NACA type foils for your sail boat...

    1: You are involved in high stakes, cut throat, international calibre competition at the highest levels where a boat lenght of speed over many miles traveled is important.
    2: Foils make you feel good about your boat.
    Even the chunkiest cruising boats use foils with aero sections and they sure as hell aren't racing. Take some time and make a list of the boats in production that use shaped foil boards fore and aft. Now make a list of the production boats that use flat plates to do their fluid work. Give us an idea as to how the world's best boat builders continuously slap flat plate appendages on their boats when they must know by now that is all they need and the flat plates are a whole lot easier and cheaper to build. Somehow, I'm missing the connection between effective shaped foils in wide use by a huge variety of craft and the argument here that a Sanford and Son solution is just peachy. What's next guys...? poorly executed joinery that is filled with thickened epoxy and a smile in the direction of the customer while he is told that it works just as good as a properly made joint? Has America really stooped to that sort of process as a justification? And you wonder why we are running down the path to becoming a Second World nation. Bondo Nation
    Last edited by Chris Ostlind; 04-13-2012 at 10:32 AM.

  32. #67
    Join Date
    Aug 2000
    Location
    Auckland ,N.Z.
    Posts
    23,351

    Default Re: Which naca profiles for sailingboats

    How come we haven't done tubercles yet.
    I say they're worth considering on a rudder because they delay stall and they're no good on a centreplate because you can't get the board up anymore.

  33. #68
    Join Date
    Aug 2006
    Location
    Rockford, IL
    Posts
    8,055

    Default Re: Which naca profiles for sailingboats

    What's a "tubercles"?

  34. #69
    Join Date
    Oct 2000
    Location
    Padanaram, MA USA
    Posts
    9,159

    Default Re: Which naca profiles for sailingboats

    Quote Originally Posted by Nicholas Scheuer View Post
    What's a "tubercles"?

  35. #70
    Join Date
    Aug 2006
    Location
    Rockford, IL
    Posts
    8,055

    Default Re: Which naca profiles for sailingboats

    Well, learn sumthing new every day. However, that's as far as it will go for me; Too "high performance" for boats I'm interested in. As for inability to drawing up a daggerboard, wouldn't sizing the slot to fit a tubercle, then having half of a terbucle exposed at the bottom of the slot fix that obstacle?

    Would you offer a pronumciation key for "tubercle"? Do I start with "tube" (long U) or "tub" (short U)?

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •