Bieker B6

[joe.bersch]

Yes it does. We will be too busy rigging to use your surfboard. Come take a look this weekend. Better yet, come help! I've got to take a couple days off to work out of town. I hope the snow is deep at Vail/Beaver Creek next week. Wish I had a chance to put the skis on before hand, but not in the cards.

Plan is to paint on Monday and Tuesday next week. Racks going in tomorrow. I will post some more photos soon.

FJB

 

[xfire]

We integrated a gybing board in a Fireball in the late 70s. What we learned is revealed in the technical discussions above. But, I'd summarize our experience:

1. The board doesn't gybe, the boat aligns to leeward at the actual direction of travel. In a Fireball with chines and runners, that reduces a bunch of drag and the expense of some very inefficient lift from the hull.

2. It essentially drops the jib tack 3 or 4 inches to leeward. You must re-think the jib trm point and trimming technique or it won't improve your boat speed. (and maybe jib design.)

3. MOST IMPORTANT. If you A.B test without re-thinking your jib setup, you won't get valid results. I think this why some empiricists think gybing boards do not work.

 

[-TG]

Boat is looking great... can't wait to see her up close... Reasoning on Tuttle vs Brown on the rudder?

when is the reveal party at Fiddlers... Thurs or Fri? As it looks now I'm having difficulty just making the weekend.

 

[allanfj]

Boat is looking great... can't wait to see her up close... Reasoning on Tuttle vs Brown on the rudder?

Great question...I think I know the answer. could have to do with customer service and customer satisfaction...

 

[Irrational 14]

Waterat/Tuttle - The best, period.

 

[joe.bersch]

Archie and others like Irrational feel pretty strongly that the Tuttle rudder and Foils have higher lift with less drag. That meant a lot to me. I have used a prevuous Bieker/Brown rudder with smaller foils. The new Brown version uses the same rudder which in my opinion is just too small. Paul thinks the same rudder section and profile but deeper is the answer. He is planning to do a new foil design to go along with the deeper rudder. We could not design and build that in time to sail the boat next week. I think Henderson Boat Company will be offering that option on future boats. Meanwhile, Larry Tuttle has been a pleasure to deal with and very understanding and accommodating of our schedule, etc. I am looking forward to his high quality product and equally important his willingness to stand behind it.

 

[joe.bersch]

Tick, tock. Final primer applied. Top coat today. Clear coat for interior on Thursday, Friday. Rigging Saturday, Sunday, Monday. Driving Tuesday, Wednesday. More rigging? Sailing on Thursday? NOOD on Friday. All still sounds doable, right? Come find out.

 

[Andrew P]

Tick, tock. Final primer applied. Top coat today. Clear coat for interior on Thursday, Friday. Rigging Saturday, Sunday, Monday. Driving Tuesday, Wednesday. More rigging? Sailing on Thursday? NOOD on Friday. All still sounds doable, right? Come find out.

Looks like she'll fly

 

[WCB]

Nice work fjb! It's been fun watching the progress in this and the I14 forum. Wish I could build the Moth as fast you guys have done the 14.

 

[Pete M]

fjb - boat gonna make it old pal?

 

[joe.bersch]

Pete:

We are planning on it. The boat is leaving tuesday withan eta San Diego on Wednesday night. I am away on business (really) but I see the boat is getting its final clear coat tonight. Rigging should commence tomorrow. Are you gonna make it? I am getting some weak, tasteless beer for you on Friday night.

Joe

 

[Pete M]

Are you gonna make it? I am getting some weak, tasteless beer for you on Friday night.

Not gonna make it this year - leaving on travel sunday - bad planning. might make it down for a day tho

and excess hops in IPAs was only done to hide the flavor of the beer after it had gone bad anyway

 

[Presuming Ed]

So I dropped Dave Hollom an email, drawing this thread to his attention. He's kindly sent a few comments.

Sailing Anarchy Reply
Nice to see that myarticle has produced so much discussion. There are, however, a numberof points I would take issue with.

FJB notes that he hasto sail with more leach tension with a gybing board. The effect of agybing board is to increase the lift on the board and thus decreaseit on the hull. As lift is assumed to have its point of action on thequarter chord line of both hull and board if you decrease lift on thehull the combined centre of action must move aft. Ideally you wouldmove the mast back to compensate but if this is fixed then anincrease in leach tension will make the balance better so, in thisinstance the theory seems to agree with the practice.

Baltic Bandit seems tohave invented his own version of fluid dynamics and his use ofvectors is something to behold. If, as he suggests, you can arrangethe vectors in any direction you want you can indeed prove anythingyou want but it will not necessarily be true. By definition thedriving force vector must be aligned with the direction of travel(not necessarily the centreline of the boat) or otherwise it wouldnot be a driving force vector and also, by definition, the side forceor heeling vector must be normal or at right angles to the drivingforce vector or otherwise it would not be a side force vector. Whenyou bear away the driving force vector is not, as you suggest,significantly more aligned with your course made good (CMG). It hasand always will be totally aligned with your CMG no matter whatcourse you sail or otherwise, as mentioned, it would not be a drivingforce vector. What I think you are trying to say is that as you bearaway the resultant or total aerodynamic force vector is more alignedwith your direction of travel, which will increase the driving forcevector and decrease the side force vector. However, as Ting Tongpointed out, the effect of a gybing board is not the same as bearingaway. The effect of a gybing board is to rotate the boat relative tothe rig so that the centreline of the hull is more aligned to theCMG. Provided the direction of travel does not alter (e.g. the CMGdoes not become wider relative to the apparent wind) then the rigforces will remain the same. If they were optimal before, they willstill be optimal and as righting moment in no way increases, the rigcannot be powered up more and furthermore, there will be no increasein driving force. Actually, there is an argument to suggest that theyawed hull of the boat with a non-gybing board may have a greaterrighting moment than the un-yawed hull of the boat with a gybingboard. Longitudinal stability is greater than transverse stabilityand as heeling force on the boat with the non-gybing board is now atsome angle between lateral and longitudinal (the leeway angle) thegreater longitudinal stability must contribute and increase slightlythe total righting moment.

I have great difficultyunderstanding his point about appendage size and speed. What I thinkhe is trying to say is that because we now sail faster, leeway anglemay well stay the same even though the appendages are smaller. Yes,if you can sail faster, because lift varies as the square ofvelocity, you can make the appendages smaller and still sail at thesame leeway angle. However, if the foil area were reduced by 25%speed would have to go up by around 12% to keep the same leeway angleor lift coefficient (Cl). I know that over the years speed hasincreased as appendage area has reduced, but not by those sort ofamounts so that, to maintain the same side force, leeway angles musthave increased.

Likewise, I am at aloss to understand what he means by the canoe body lift beingproduced by "purely static drag effects" or even by "turbulentdrag at the edges". What are static drag effects and what isturbulent drag at the edges? Lift cannot be produced by drag. Drag isa force that works at right angles to lift and has no component inthe direction of lift so that none of the drag force can contributeto lift. Canoe body lift is produced in the same way that lift on thefin is produced, by circulation. At first sight the canoe body wouldseem to have a very small span and would thus appear to be ratherinefficient at producing lift. However, when attached to a fin, thecirculation from the canoe body will run down the fin to the tip,where it will exit as the tip vortex, giving it a very much improvedspan, and at the other tip, the water surface, the greater length ofthe hull means a lower Froude number (Fn) and thus less lift inducedwave drag. True, some of the vorticity will be lost at the junctionof the fin with the canoe body, by vortex shedding at this junction,which will reduce somewhat it's effective span, but careful shapingof the junction will minimise this vortex shedding and ensure thatmore of the canoe body vorticity reaches the fin tip, maximisingeffective span.

The fin and the canoebody, when it comes to producing lift, have a symbiotic relationship.The fin (and rudder) efficiently extend the canoe body circulation tothe maximum draught (span) and in return the canoe body, by virtue ofits higher Fn, extends the fin circulation efficiently to or abovethe water surface. In combination they work far better than asindividual units. The sum of the total is more than the sum of theparts.

Yes, the Moth doesproduce its lift from a very short chord fin and as the hull is notin the water it obviously does not produce any lift. However, thelifting foil on a Moth is fully submerged and thus any free surfaceeffects are very much reduced. The vertical (when upright) foil on aMoth which pierces the surface should, if correctly set up, berunning at zero yaw producing no lift so that surface effects linkedto lift are non- existent with this foil. All the lift forces, bothvertical and lateral, are produced by the submerged foil. That'swhy they are heeled to windward so that there is a component of liftworking laterally to resist the aerodynamic side force. (See myarticle in Seahorse issue 358). However, once the lift reaches thesurface on a conventional boat, either through carry over lift or bythe yawing of the canoe body, it pays to have a long surface runningat a lower Fn.

His point about themovement away from full keel boats with large lateral areas to highaspect ratio fin keels of necessarily smaller area only reinforces mypoint about leeway. The leeway of the fin keel boat, because of itssmaller area, will be larger than that of the full keel boat and yetit will be faster. QED? Incidentally, the higher aspect ratio (AR) ofthe fin keel will not reduce induced drag provided the draughtremains the same. Yes, induced drag does vary inversely as AR butonly for the same Cl. Because the smaller area fin must run at ahigher Cl, to produce the same lift force, the higher Cl cancels thehigher AR and induced drag remains the same (Do the sums). There is atrick question posed by professors of aeronautics to first yearstudents which asks, "What happens to induced drag if, for a givenspan, AR is doubled." Most say induced drag will halve but theanswer is, it will remain unchanged.

He says that he is notconvinced that the downwash reaches the rudder. As Ting Tongsuggests, go sail in the downwash from someone else's sails andthen see how far you think it reaches. He also intimates that the finand rudder form a slotted system and goes on to say, "And we KNOWthat such systems generate more lift than unslotted ones." He doesnot seem to have grasped the fact that lift, at any moment in time,is fixed. You cannot increase it and have no need to increase it.What we are interested in doing, is not increasing lift, but inproducing the required lift at minimum drag so as to maximiselift/drag ratio, and whilst slots allow a higher Cl to be produced,there is always a drag penalty, which is not what we are after.Besides, the two foils are too far apart to act as a slot.

Ting Tong seems to havegrasped the gist of my argument and has argued many of the pointsbetter perhaps than I can.

Simon N seems to thinkthat Archie doesn't need a gybing board because he is so good. I donot know of any competitive sailor who, provided there was enoughtime to develop and integrate a system that he thought was faster,would not use it. Competitive sailors are after every advantage theycan get. If they don't use gybing boards they have probably triedthem and found them wanting and a top sailor will suss out whether itis good or not, quicker than anyone. And incidentally, a gybing boardis totally different, in its effect, to an asymmetric or camberedboard. (See my article in the next issue of Seahorse). Also I reallydon't see, if you have to change the board every time you tack asyou do on a multihull or canting keel boat, why anyone would use asymmetrical board. The asymmetric foil will always be quicker, thoughnot necessarily because the canoe body lift is reduced, but becausethe cambered foil can, with advantage, be smaller. Your point aboutmoving the board on a "C" class cat only proves that the hullproduces a fair amount of lift if it is at some yaw angle.

Mark1234 makes thepoint that aircraft designers always try to align the fuselage withthe direction of flow, which is quite correct. However, aircraftdon't operate at the air/water interface. Their fuselage is not onetip of a foil. It is a bit of material midway between two tips and sohas little effect on the efficiency of those tips in reducing induceddrag. By contrast, on a boat, the hull does form one tip and so has alarge influence on induced drag. However, it might be of someinterest to note that tip tanks on aircraft, which quite obviously doform part of the tip, are not aligned with the direction of flow.

Daniel Holman mentionsthat frictional drag reduces with reductions of area but that induceddrag increases with reductions of area. Actually, frictional drag maywell reduce with reductions of area but it may also increase. Bestlift/drag for profile drag occurs when a line drawn from the originof the graph touches the polar at a tangent. For a given lift forceand speed, Cl rises with reductions in area. If we gradually decreasearea so that Cl rises we will move along the lift/drag polar in anupward direction. Whilst the Cl remains below this point of bestlift/drag, drag will indeed reduce with reductions of area. However,once the Cl is above this point, drag will actually increase with anyfurther reductions of area. Also, induced drag does not necessarilyincrease with reductions in area. As long as the span remains thesame, induced drag will not alter and if span is increased induceddrag will fall, even though area has been reduced.

Baltic Bandit makes thepoint that as you ease the sheets the sails change shape and thatthey become fuller which in itself is an advantage. This is just aset up problem. With a different set up, i.e a traveller or leachtension controlled by the kicker rather than the sheet, there is noreason why sail shape should not be maintained, at least over thesmall angles we are talking about. And, if it was an advantage tohave a fuller shape, bearing in mind that with a gybing board all youare doing is rotating the hull beneath the rig and the sail will beat the same angle of incidence to the apparent wind as on anon-gyber, why has he not already got that fuller shape? I think wehave covered his vector arguments but he goes on to say that absent agybing board, the lateral contribution of the hull is fixed which ofcourse it is not. It is quite obvious that just varying the boardsize will alter the contribution of lift from the hull.

The purpose of a slotis to re-energise the boundary layer on the low pressure surface of afoil. If you try to bend the air (or the water) too much there is notenough energy in the boundary layer to ensure attachment to thetrailing edge and separation occurs, which increases drag and reduceslift. By allowing higher energy fluid to transfer to the low pressureside of the foil system the boundary layer is re-invigorated helpingit to reach the trailing edge without separating. Also, the effect ofthe slot is to increase the lift on all the elements not just theleading one. He also mentions "By injecting flow into the lowpressure side, you increase pressure without dropping flow speed."According to Bernoulli you cannot increase pressure without droppingflow speed. If anything in physics is written in stone it isBernoulli's theorem and so, with the greatest respect, I would backBernoulli rather than him. However, as already mentioned slot theoryis not what we are talking about. Bi-plane theory is more applicable.Finally, yes the rudder producing lift (weather helm) does help towindward but not because as he says, "the combination of the rudderand the main foil has a bit more lift in it which in turn drives youto weather a bit more", but because rudder lift, for a number ofreasons, is more efficient than lift derived from the fin. Asmentioned, lift is fixed. You cannot increase it and drive up toweather. The only way you will point higher is by increasing thelift/drag ratio which, as lift is fixed, can only be achieved byreducing drag, which is what the right amount of lift on the rudderdoes.

In his write up on hisnew boat Paul mentions that he prefers a gybing board because it canhave a smaller area. In this I have to disagree. If the foil iscorrectly sized so that it is working at a Cl just within its lowdrag bucket and is therefore of minimum effective area, if you takethe lift of the canoe body away by using a gybing board, the boardwould then have to support not only the lift it was producing beforebut also the lift that previously had been produced by the canoebody. Because it is now producing more lift you would have to makethe board larger if it was still to run at the same Cl, efficiently,just within its low drag bucket.

The only way you couldmake the board smaller and still have it work would be to use an oldfashioned (but still good) so called non-laminar foil such as a NACAfour digit. Because, as they say in Yorkshire, "You don't get owtfor nowt", if you forsake the low drag afforded by long runs oflaminar flow and accept that the drag at low Cl's will be higheryou will, in return, get lower drag at higher Cl's. Thus NACA fourdigit and similar foils, because they are not designed specificallyfor laminar flow, can work efficiently at quite high Cl's. There isthus no need to size them to remain within any low drag bucket;indeed best lift/drag is achieved at a relatively high Cl of around0.85 for a NACA0012. However, correcting for AR effects that equatesto a leeway angle of around 10-11 degrees. I know I said that canoebody lift might be quite efficient but there must be a yaw angleabove which its efficiency diminishes and I would suspect that itwould be well before you reached these sort of yaw angles. Thus, theonly way you could utilise such high angles would be to independentlyyaw the daggerboard i.e. have a gybing board. However, it is notreally practical to run a gybing board at such high angles of attack.Because a Cl of 0.85 is about two thirds of the way to Cl max youwould not have to lose too much speed before the foil stalled so thatdownspeed situations could become a big problem. Also, with such asmall area you are at a huge disadvantage when stalled out before thestart. You find yourself drifting to leeward at a far greater ratethan the boats around you and find it difficult to engineer thatvital room to leeward in which to bear off and accelerate. Bycontrast, best lift/drag on a modern laminar foil with a wide lowdrag bucket occurs more like one third the way to stall Cl so thatdownspeed manoeuvring is easier and because the board is larger,maintaining your place on the start line is far easier. Although thearea is larger, because Cd is lower, drag may be less than the farsmaller non-laminar board and it would be much more user friendly. Iam still therefore of the opinion that the board can be smaller onthe non gybing boat and not, as Paul suggests, on the gybing boat.Perhaps Paul could explain just why he thinks a gybing board can besmaller than a non-gybing board?

I have been fortunateenough to have done a considerable amount of testing in are-circulating water channel (a flume) and it is relatively simple insuch a facility to set the flume running at a particular speed andthen, with the help of radio control, to simultaneously alter trimtab, rudder and yaw settings so as to maintain an equilibrium sideforce and then note the effect on drag. I know a fin with a trim tabis not a gybing board but it is a means of altering the ratio of lifton the appendages to that on the canoe body. I can say that,according to our tests, eliminating canoe body lift was never a fastsolution. Minimum drag, for a given side force, was always achievedwith some appreciable yaw angle which would suggest that canoe bodylift is not as inefficient as some people would have us believe.Indeed it must be quite efficient to produce the results we observed.

Dave Hollom

2nd March2011

Sailing Anarchy Reply.doc

 

[SimonN]

So I dropped Dave Hollom an email, drawing this thread to his attention. He's kindly sent a few comments.

Sailing Anarchy Reply
Simon N seems to thinkthat Archie doesn't need a gybing board because he is so good. I dont know of any competitive sailor who, provided there was enough time to develop and integrate a system that he thought was faster, would not use it. Competitive sailors are after every advantage theycan get. If they don't use gybing boards they have probably triedthem and found them wanting and a top sailor will suss out whether itis good or not, quicker than anyone.

Dave Hollom

This didn't half make me laugh. I was stunned by the science behind the debate! He even gives the key in what he writes. Archie doesn't believe in gybing boards and therefore isn't willing to give the time to develop and integrate one into his boat. That doesn't mean they don't work. By the same argument, my "proof" that it does work is that Trevor B, Howie and the boys did spend tim to develop and integrate gybing boards into their boats and dominated the fleet. As Trevor has posted, he is convinced gybers are better/faster.

Arcie has stated that he wants to build a more and more simple boat. that's great. Does it mean that some of the complex systems we see on other boats don't work? What it means is that it doesn't work for Archie. By way of example, i would imagine that Archie would find Mike Lennon's 14's a nightmare to sail, with all their string and systems while Mike would probably find Archie's boat equally as nightmarish. Both would do better in their own boats.

So, IMO, this argument by Dave is meanlingless. My argument for Archie's anti gyber stance is simple. Archie doesn't believe in them and has built a boat around what suits him. He is totally comfortable in his boats and that, combined with great skill and the best training ethos I have seen in 14's has made him a winner. Archie rightly identified that spending more time practicing his tacks on Manly Circle was going to do more for his championship ambitions than anything else. He is not prepared to spend time and money to hack up his winning boat in order to try something he doesn't believe in. However, I wonder what would happen if there were 2 identical boats on the beach, one with a gybing board that worked properly and had all the systems fitted and one without, and Archie went tuning with each, back to back, against a proven benchmark. My money says he would probably show that the gyber was faster. However, I have a sneaking suspicion that even then, he might not go with it because of his strong belief in the KISS principal.

 

[belouder]

Don't know nuthin' about gybers, but I did get to drill a few holes in the B6 tonight!! Stopped by Hendo's shop and was met by the sound of a die grinder and 70' Roller Rink muzak (Bee Gees doin' it!!). Kris was working on the sexy kite throat and Joe was attaching foot straps. He handed me a drill and walked away. Wow!! But seriously-they are cranking away in there and it looks very nice. I thought folks might want to see some pics.

/monthly_03_2011/post-12225-088533300%201300081614_thumb.jpg

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[belouder]

Some more pics.

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[belouder]

One more-the pointy end....

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[BWR]

That will look good sitting in my garage in a day or two! Have a safe drive Kris and Kim, we'll have cold greenies waiting!

 

[joe.bersch]

Funny, Brad. They won't have time to stop. To say we are rigging might be an exaggeration. We are still in the "fitting" stage. Bundy, Bieker and Hendo are all at the shop working right now. Alan J and Alan D are on the night shift with me. Boat hits the road tomorrow morning. Arrival San Diego Wednesday night if all goes well.

FJB

 

[BalticBandit]

Don't know nuthin' about gybers, but I did get to drill a few holes in the B6 tonight!! Stopped by Hendo's shop and was met by the sound of a die grinder and 70' Roller Rink muzak (Bee Gees doin' it!!). Kris was working on the sexy kite throat and Joe was attaching foot straps. He handed me a drill and walked away. Wow!! But seriously-they are cranking away in there and it looks very nice. I thought folks might want to see some pics.

Hendo does nice work..