The first wing keeled boat I sailed was a Sadler Starlight 35 back in the early 1990’s. For that yachts’ design the function was very much about generating lift, thus giving a reduction in wetted surface area. How effective it was I really wouldn’t like to say, although she was very quick for her size / displacement off the wind (she was designed as a cruiser/racer). My one criticism of the design is that although the generated lift would be beneficial when sailing off the wind, hence sailing relatively flat, however when on the wind and on ‘normal’ angles of heel, surely the lift becomes counterproductive? (it must add to leeway).
Looking at Claudio’s drawings of Australia II and in particular the keel renderings, I would have thought that its function was the same as that utilised in the Starlight 35.
Seriously, retirement?!! If so many congratulations - but hang on a minute, you can’t possibly be anything like old enough!! (We’re not like women who just carry on having anniversaries of their 21st!!).
Thanks Row, to me retirement as got nothing to do with age, it’s about having the right amount of ballast to cross the finish line without nose diving… going down wind
But I’ll take your advice and announce my 22nd on my next birthday :rolleyes:
Here some comments : http://mly.gamalanhost.net/pop_printer_friendly.asp?ARCHIVE=true&TOPIC_ID=1036
From pictures and drawings I observe a negative pitch of the wing, therefore I do not understand how the lift is achieved. Same comment for the Australia II that have about -3°.
I tend to agree that it may be more stable when sailing in rough water, but the ballast is not very deep and I wonder how can be managed with strong winds above 12/15kt, unless is carrying a lot of weight !.
“Row” Thanks for the explanation, I think it’s interesting that something tried to achieve with the design of the keel.
“Alan” Congratulations on your retirement and hope that you do everything you have planned to do, with his new free time.
-For my part I think I will follow the advice of a Korean man who is my friend.
I asked him when was retiring (The man is 94 years old, and continues to work in his factory, and he not doing it for the money) He made a brief silence and then he replied to me: I do not advise it, man who retires, dies soon.
-It is really the secret of his longevity maybe. He works forged stainless-steel plate with a hammer, and he make it without corrective lenses.
-And their work is incredibly good.
Some may already use this layout to start building a Plug.
Of course my job do not stop here.
The next step will deal with the Displacement check via the COA.
It may be happen to modify slightly the shadows with small fairing.
About Australia II: I did read somewhere that the inclination and lift was negative on the wing keel, so that when it heeled, it would ‘lift’ towards the windward, giving better upwind performance. Counter-intuitive, but that is what made Australia II so unique, and faster than it’s competition.
-Dear “Claudio” sorry if I do not answer to you, in the morning before going to work, but it was very interesting articles from the pages to which you sent us, and I had to read it in detail. Which I’m doing right now, not easy to reason to me.
-I try to analyze the effect of a wing with negative rake angle, located just behind the “CG”, I fill my tank measurement IOM, and I put a sailboat. As would be logical to think, if you press exactly behind the “CG” immerses the stern hull, and logically to offset the amount of water displacement, the bow emerges. The following argument I leave it to you, maybe the effect is greater planing hull, I do not know.
-One thing that seems pretty logical is that having a flat surface in horizontal position, would act as a brake vertically, and decrease the oscillation longitudinal hull, which I think would also be in biggest speed.
-I don´t know, what do you think.
Hi Alberto,
I have read the same posts and nothing it is mentioned about the tilt I observed in the attached pictured and on the Chevalier drawing extracted from the “Bible” although I found an error on the described characteristics that induced me to make initially an error on the beam.
The negative tilt reason ? I do not knows except of what Toddster says.
Cheers
Claudio
-In pictures, (Claudio just put it), I seems it: the keel not only has negative angle, also has airfoil (flat below and convex above). What would make an airfoil positive.
-And to make things a little more complicated, also seems to have anedro (opposite dihedral) which maybe would confirm your theory that gives more lift upwind.
I think it’s very difficult to analyze, and even more, without accurate data. How you see it?
Aussie II is on permanent display in the Western Australian Maritime Museum in Fremantle.
I’ve read a lot on Wing Keel and how the boat performs, comparing one to the other and there were many variations, but no one talks about how a wing keel works.
Closest I found was article partly written by Claudio’s friend, Eric Sponberg…read PDF here
Another point is that in combination with the wing keel, these modern 12’s also used trim tab that is added to the trailing edge of the keel fin, you can see in this photo.
Btw, love to measure up the model in the background.
I’m now cautious about applying the wing keel onto RC model as the small scale may not be as effective as on large boat, reading the article angles and position of the wing along with its aspect play important role.
As alternative option that may be safer to consider is having a torpedo type bulb that can be attached base of the inverted keel shape that can be exchanged by a wing section clip-on where can compared differences on a RC model.
An aerofoil with a flat bottom section has zero lift with the flat bottom at a negative angle.
The negative setting on the winged Keel may well be at zero to the direction of travel.
Or, the winged Keel may be producing a downwards force at speed, lowering the Hull and giving a longer waterline!.
Is there a specified waterline for this class of yachts - - - at rest!.
The Ranger actual calculated COA is giving a Displacement of 4655cm3 without Rudder volume. This results is lower by 210 cm3.
The rudder cannot recover this volume difference therefore some shadow’s fairing is needed under the water level.
The LCB is at -3.4% ol LWL from shadow 5.
The Prismatic Coefficient is 0.54
What is bothering me at the moment, is the fact that resizing the JClass and 12Metres all to 1270mm, there is a difference of +1.5kg.
for the Australia II.
Unless errors from my side, at the moment, the Australia II shows a displacement of about 6.3kg, while the JClass Ranger is around 4.8kg.
This difference may put the Australia II in disadvantage when competing with the other.
I wonder if finally JClass and 12Metres could meet together on the same racing !
This direction you found, it’s great, I’ll get to read. The question is, I understand something in the next 6 months? maybe.
Talked yesterday with a friend, he told me, he had read in the 90’s, an article explaining that the negative impact keel of Australia II, replacing X amount of ballast, so could be more lighter, thus having an advantage in their favor.
My friend promised to look for the magazine.
my summary about widgets is that they reduce drastically the fin vortex, improve a bit the close hauled and allow shorter (deep) keel but has a negative performance when running due to increased drag and wet area.
The modern AC design abandoned that feature and added foils to the bulbs. This give me the impression that the “vortex criteria” was not an essential design consideration.
Was probably a nice experimental work in the middle 80’.
Actually the fashion is to put immersed recurved foils close to the hull…
Personally I will continue to give my preferences to Vintage Classic keels with or without Trimmers.
Another step forward, this time with the Ranger Deck.
Not many interesting pictures available on the web and on the “Bible” of F. Chevalier, nevertheless the few ones found are integrated in my drawing to help the modeler to make his own choice. Only basic details made, the Integrated picture is self explanatory.
maybe.