Re: [bolger] Re: Micro with chine runners?

Well, Harry the claim is they work, but...


Speed might come into it, and slender hulls make for higher speeds. However, the slender hulls are immersed sufficient to resist leeway themselves. I'm far from persuaded on a number of grounds. Bernd has many capable and attractive catamaran designs, and he specifies those small horizontal triangular panels on some designs be fitted to only the inner chine of each asymmetric hull, the sloping side. The outer side of the asymmetric hulls are near vertical - like a knife cutting through the water, no? The small "anti-vortex" appendages are supposed to reduce drag along the long inner hull side ... reduced drag for less leeway... ok then, so what's happening on the other windward hull windward side?


One attempt at an explanation for the claimed efficacy that gets around is to point at the winglets seen fitted normal in orientation to airplane wings at the tips. additionally, the wing chord is usually significantly reduced at the tip. The comparison falls short (no pun intended) on the relative geometries. Winglets are like endplates on the foils/keel of a boat, acting to reduce votices at the tip and downwash curving over the wing or foil. The winglets/panels are noticeably not appended to a wingless fuselage of an airplane - as TFJ wryly pointed out. Panels resembling "vortex anti-generators" in size and shape are however seen mid-body on missiles... at that power to weight and speed they must have been found to be satisfactory - but then how does a missile come in for a soft landing?


Pete Hill fitted the specified panels to his boat build ORYX, but shortly after crossing he removed them and fitted a low aspect keel to each hull (documented early in the blog below). Pete and Carly Hill have a little Q&A at the end of Carly's latest blog article touching on the panel issue:



"J.H.    What do you like about ORYX, what would you do different?

Pete   Oryx is a very comfortable cruising home and she attracts favourable comments where ever she goes. I think Oryx would be a better boat if the hulls where fatter. The present waterline beam to length ratio is a little over 12:1. This is probably needed with the anti vortex panels, but they did not work very well on Oryx. Mr. Kohler talks of his average speed on his 'Pelican' as 9.6 knots! Maybe the anti vortex panels work at those sorts of speed, but Oryx's average is somewhere around 5 knots..."
"ORYX" ODYSSEY: BRAZIL: - FOOTBALL MANIA!
Here is an article on anti vortex panels by a Catamaran designer.

http://www.ikarus342000.com/Antivortexp.pdf

and here is a  boat he used them in instead of dagger boards or keels

http://www.ikarus342000.com/PELICANpage.htm

They are apparently only effective on very slim hulls.

HJ




On 7/26/2014 1:09 AM,c.ruzer@...[bolger] wrote:
Long ago now a Bolger friend, the late Thomas Firth Jones, in his"Multihull Voyaging" (1994) looked at this type of hull appendage. Dating back to the late 1960's, early 1970's, especially amongst certain Wharramites, claims began circulating of the much improved pointing and windward performance of boats after the fitting of "vortex (or  sometimes "anti-vortex") panels" (see Sea People magazines, etc.). The explanations often conflate with those of the "chine runners" magic today.

Anyway, in case you haven't seen Jones' 1994 book I'll copy below from page 76 the gist of what he thought of the "thinking":

"For years, both Rudy Choy and James Wharram tried valiantly to design catamarans that would go to windward without daggerboards. Many of Wharram's designs still don't have them. Some of his builders put them in anyway, and others put in "vortex generators." People who are attracted to Wharram's cats tend to originality. Vortex generators are long shallow fins that stick out perpendicular to the sides of hulls, and allegedly trap water and keep t! he boat from slipping sideways without deepening draft. People who have installed them like them, and claim that they improve light-air performance as well. When this technology reaches the aircraft industry, it certainly will make airport runways less congested."


Out on the edge there


"= In the *10th* Second of Forever =
I thought of the sea and your white yacht  drifting ...


(..on the edge of the edge of the edge)


= In the *5th* Second of Forever = 
I thought of the vermillion deserts of Mars ~ the duned forests of Venus ...


= In the *3rd* Second of Forever =
I thought of '|rain|' against the window - and -  I thought  of the > wind > >


= In the *2nd* Second of Forever =
I thought of the *pair*  of  >broken<  **shades**   ___  lying __  on  _the tarmac_


= In the >1st< and  +final+  *Second* of Forever =
I thought of the  long past  that had  ~> lead ~> to  ~>   ~> NOW <~  and  never  ~>never>~>   `never"

I got vortex generators ;)
Set me any more straighter
I've got an orgone accumulator
Those energy stimulators
 And it makes me feel greater
 It's a back brain stimulator
 It's a cerebral vibrator
But an orgone accumulator
 Is a superman creator
 It's no social integrator
 It's a one man isolator 
 I'll see you sometime later
With apologies Mr creator
For


time is worth much more than paper
but seldom burns
with such bright flames as these drafts
(Robert Calvert)
Robert Calvert / Knut Gerwers - Ten Seconds of Forever - entry / ! data

 




This email is free from viruses and malware becauseavast! Antivirusprotection is active.





---In bolger@yahoogroups.com, <c.ruzer@...> wrote :

awesome post. his book, ow resistance boats, was a huge inspiration for me and inspired my to design and build a sprit rig for my dinghy; which turned out to be the perfect rig for that boat and has given me years of great sailing...almost two decades, in fact. i have a lot of respect for the late Mr Jones.


Long ago now a Bolger friend, the late Thomas Firth Jones, in his"Multihull Voyaging" (1994) looked at this type of hull appendage. Dating back to the late 1960's, early 1970's, especially amongst certain Wharramites, claims began circulating of the much improved pointing and windward performance of boats after the fitting of "vortex (or  sometimes "anti-vortex") panels" (see Sea People magazines, etc.). The explanations often conflate with those of the "chine runners" magic today.

Anyway, in case you haven't seen Jones' 1994 book I'll copy below from page 76 the gist of what he thought of the "thinking":

"For years, both Rudy Choy and James Wharram tried valiantly to design catamarans that would go to windward without daggerboards. Many of Wharram's designs still don't have them. Some of his builders put them in anyway, and others put in "vortex generators." People who are attracted to Wharram's cats tend to originality. Vortex generators are long shallow fins that stick out perpendicular to the sides of hulls, and allegedly trap water and keep the boat from slipping sideways without deepening draft. People who have installed them like them, and claim that they improve light-air performance as well. When this technology reaches the aircraft industry, it certainly will make airport runways less congested."


Out on the edge there


"= In the *10th* Second of Forever =
I thought of the sea and your white yacht  drifting ...


(..on the edge of the edge of the edge)


= In the *5th* Second of Forever = 
I thought of the vermillion deserts of Mars ~ the duned forests of Venus ...


= In the *3rd* Second of Forever =
I thought of '|rain|' against the window - and -  I thought  of the > wind > >


= In the *2nd* Second of Forever =
I thought of the *pair*  of  >broken<  **shades**   ___  lying __  on  _the tarmac_


= In the >1st< and  +final+  *Second* of Forever =
I thought of the  long past  that had  ~> lead ~> to  ~>   ~> NOW <~  and  never  ~>never>~>   `never"

I got vortex generators ;)
Set me any more straighter
I've got an orgone accumulator
Those energy stimulators
 And it makes me feel greater
 It's a back brain stimulator
 It's a cerebral vibrator
But an orgone accumulator
 Is a superman creator
 It's no social integrator
 It's a one man isolator 
 I'll see you sometime later
With apologies Mr creator
For


time is worth much more than paper
but seldom burns
with such bright flames as these drafts
(Robert Calvert)
Robert Calvert / Knut Gerwers - Ten Seconds of Forever - entry / data

 

Long ago now a Bolger friend, the late Thomas Firth Jones, in his"Multihull Voyaging" (1994) looked at this type of hull appendage. Dating back to the late 1960's, early 1970's, especially amongst certain Wharramites, claims began circulating of the much improved pointing and windward performance of boats after the fitting of "vortex (or  sometimes "anti-vortex") panels" (see Sea People magazines, etc.). The explanations often conflate with those of the "chine runners" magic today.

Anyway, in case you haven't seen Jones' 1994 book I'll copy below from page 76 the gist of what he thought of the "thinking":

"For years, both Rudy Choy and James Wharram tried valiantly to design catamarans that would go to windward without daggerboards. Many of Wharram's designs still don't have them. Some of his builders put them in anyway, and others put in "vortex generators." People who are attracted to Wharram's cats tend to originality. Vortex generators are long shallow fins that stick out perpendicular to the sides of hulls, and allegedly trap water and keep the boat from slipping sideways without deepening draft. People who have installed them like them, and claim that they improve light-air performance as well. When this technology reaches the aircraft industry, it certainly will make airport runways less congested."


Out on the edge there


"= In the *10th* Second of Forever =
I thought of the sea and your white yacht  drifting ...


(..on the edge of the edge of the edge)


= In the *5th* Second of Forever = 
I thought of the vermillion deserts of Mars ~ the duned forests of Venus ...


= In the *3rd* Second of Forever =
I thought of '|rain|' against the window - and -  I thought  of the > wind > >


= In the *2nd* Second of Forever =
I thought of the *pair*  of  >broken<  **shades**   ___  lying __  on  _the tarmac_


= In the >1st< and  +final+  *Second* of Forever =
I thought of the  long past  that had  ~> lead ~> to  ~>   ~> NOW <~  and  never  ~>never>~>   `never"

I got vortex generators ;)
Set me any more straighter
I've got an orgone accumulator
Those energy stimulators
 And it makes me feel greater
 It's a back brain stimulator
 It's a cerebral vibrator
But an orgone accumulator
 Is a superman creator
 It's no social integrator
 It's a one man isolator 
 I'll see you sometime later
With apologies Mr creator
For


time is worth much more than paper
but seldom burns
with such bright flames as these drafts
(Robert Calvert)
Robert Calvert / Knut Gerwers - Ten Seconds of Forever - entry / data





a discussion of lift and drag from people who should know.

 



Not only air. Any fluid. Liquid, gas, plasma... Jet pumps lifting deep ground water, for example.

---In bolger@yahoogroups.com, <motorcyclejack2@...> wrote :

faster moving air does have less pressure than slow moving air. one component in the creation of lift.

Hi Mason,

you'd know of the old Bernoulli demonstration of the spoon loosely held dangling from the fingers, suspended vertically by the handle, and then gently moved into a stream of water falling from the kitchen sink tap? Once the curved back of the spoon blade is moved across to a certain depth within the stream of falling flowing water a force moves it further in, not out. You can see and feel it. The force moves and holds it there against gravity. Why?

Air on one side, is it? Try it all again underwater then with a jet of water, perhaps from a hose nozzle. What happens? Why?


---In bolger@yahoogroups.com, <masonsmith@...> wrote :

I like Leigh Ross’s remarks too. “Deflected flow.” Water pushed aside, pushing back. I think this analysis corresponds to my own thinking which runs on the
“inclined plane” idea from junior high school physics. The water is being deflected by an inclined plane. There is no windward vector to counteract side-way unless the keel or “foil” is inclined to the flow a bit.  This would seem to mean that even in the high speed foiling cats, the foils cannot produce “lift” unless they are at a slight angle to the flow of water past them, in other words that you have to have sideway to have lift. Which also means that you can’t get something for nothing.  Is this right?

 





No Leigh, sorry, but you can't discount ol' Bernoulli so easily. Differential pressure in the water flow is no trouble at all as there is water flowing at differential speeds within the overall flow - same as, if not exactly as air. In different places moment to moment it can flow in all different directions too and those can shear with turbulent flow between,,,  Water actually is minimally compressible, changes density, at great pressure. And it changes density with temperature too. As heat energy is added thermal expansion results. Work, done by something say that's immersed and passing through water, that is by kinetic energy, often transforms to heat energy... and so water may rise and fall in temperature, and density. Temperature, density, volume.. and pressure are linked. However, the big things relevant to ol' Bernoulli and the water a boat or  keel/foil is operating in is that it's not contained, and it flows - like a fluid, like air. If you like, that liquid water is not physically contained within a sealed pressure vessel, there is no lid or piston kept pressing down upon it. There's only the dragging downwards force of gravity on momentum, the result of other forces... And there Newton gets to visit and share with Bernoulli.


Foils change drag characteristics, sure, but pressure differentials have been measured.



---In bolger@yahoogroups.com, <Leighpilot@...> wrote :

Hi folk

I'm going to chime in at this point as it's finally come around to my own area of expertise and a personal bugbear. 

As a pilot I'm often confronted with pilots who still believe the old canard of the erroneous extrapolation of Bernoulli's Theory in which it's stated that faster airflow ( and lower pressure ) over the upper curved surface of a foil is what caused lift. This is false as the delta P is insignificant and easily disproven by anyone who has ever flown a cheap balsa glider,man aerobatic S300,or an F104 , all of which have symmetrical airfoils. Further more for an underwater foil to create " lift" under this theory , one would have to postulate differential pressure in the water flow around the foil. Water is not compressible so pressure variation are impossible. 

So where does the lift come from? It's the deflected flow of the fluid medium that causes thrust in the opposite direction to the deflected flow. Wolfgang Langewiesche s book Stick and Rudder has the best explanation. 

So what is the function of the foil?  A foil just modifies the drag characteristics of the wing/keel. Decide on the medium your foil will be in, the speed range you'll need, the loads the foil will experience and chose the profile that suits your needs. 

So we can all drop the differential pressure discussion, especially for underwater foils, the ones in an incompressible medium. :). Foils just change drag characteristics. 



Leigh Ross

484-464-1575 (C)


Way off track mate. Sea anchors ...running down wind? ...etc etc  cripes such a thing as a sea anchor doesn't need a "belly"... ..car tyres? Bolger even suggested using an anchor in bottomless water to the same end. A plate, a flat sided keel for instance aint got any "belly" .. heard of "lying ahull"? Fore-reaching, ie movement across the wind?



The "belly" of the sea anchor isn't made so as to "trap" the water to slow downwind progress and keep bow pointed to oncoming seas. A plate would do if it could be rigged, but where would you stow a large rigid plate for the purpose? The "belly" shape is designed in so as to have a thin, flexible, _stowable_ thing made of fabric, let's say canvas, stay deployed in a reliably open configuration so the anchoring due and proportional to the size of its area can work. Would you jump from a plane holding a tarpaulin, extra large bed sheet, or a basic parachute?


A plate has lift, max cl = 1.  A plate has far less drag when edge on compared to when face on. A plate keel perhaps? Perhaps a chine, or rather the immersed boxboat hull. Now operating above that take a look at the component vectors of the force acting on a sail in a breeze... and see how, and in which direction the boat moves.


"drag works best when the force is perpendicular to the surface it is acting on." 


- So how much drag on that hull or plate acts on the side face, and how much on the edge? What is the resultant direction? Yes, purely rhetorical. Include all drag effects if you wish, eg., turbulence, viscous; and those due from each direction too, eg.,  frontal area, edge and wake vortices...


"you are running down wind, the wind is pretty much perpendicular to the sail.  sailing close hauled, however, there is only enough wind behind the sail (drag) to basicaly keep it's foil shape. barely any drive is drag at that time. the boat is totally lift driven, close hauled." - Running, the apparent wind is much reduced, so of course sail force is also reduced. Close hauled apparent wind speed is higher, there is heaps of side force on the sail, it's where a capsize is more likely! And there is leeway! The small lift component of force acting on the sail is the "drive" acting in an upwind direction that propels the boat forward


What? Running the slowest point of sail? For many, broad reaching and running are the only points of sail where they have a hope of planning!


"well, if you sit in your saiboat, on flat water (just to simpify things), perpendicular to a 10kt wind with no sails up, the force of the wind on your hull will be trying to push the boat through the water with the force completely perpendicular to the keel. if you have ever been in such a situation, you will have noticed thatr the wind has no problem doing that at all. in fact, it will push the sailboat just as easily as it woud a row boat without a keel."


- What? No. Lying ahull the keel will slow the boat slipping sideways downwind. That's the point of lying ahull! That's the point of having a keel in that situation. The boat with the keel will be like a rock compared to your keel-less rowboat skittering rapidly downwind..


"so, in a situation where drag is at it's greatest, leeway is at it's greatest."


- Again, what?? The keel boat is still pretty much where it was, and the rowboat without a keel has pretty much disappeared down wind. Get in a sailing dinghy mate, sheet in and try to sail off, now raise the board - what happened? Look, with respect, I'm sorry, but this is a bit too much of a bother to go on with. If you are wedded to the rumint magical thinking that gets around about the mechanism at work behind the functioning of "chine-runners" then you are quite welcome to carry on under the spell.


"now, hoist sail and catch the wind. as the boat moves forward with greater and greater speed, leeway gets less. the faster the boat is moving the more effective the keel is at stopping leeway.

"but...wait! when the boat is moving forwards, the force of the water is no longer perpendicular to the keel. in fact, the kee is moving throught the water around 10 degrees away from being paralell to the water moving across it. in other words, drag resisting sideways motion is now very low...but leeway is also very low."

- Nope. Movement sideways, leeway, is now low compared to movement in the direction the boat is pointing. This is like the old question about two bullets at the same height, one just dropped and the other fired a great distance horizontally from a rifle at the same time - which bullet hits the level ground first?

"if your theory is right, a sailboat should be rock steady while it is not sailing" Nope, not what I said at all. Wait did I imply it was in frozen water..?

 "the keel can be a lot smaller because water is a lot thicker than air....around 4% of sail area is a good approximation, depending on keel type"


- Yes. And the faster it goes the smaller it can be too... V^2. ... ( that within a rage of inclination to the oncoming water flow)...  And we're still talking low aspect, not particularly streamlined.


"an iceberg has tons of mass under the water creating all kinds of drag, but if you stuck a big sail on one it would never sail up wind; only down wind. that's because the underwater surface of an iceberg isn't shaped to create lift. if it was, you could sail one up wind."


- If it was kinda rectangular or triangular prism like below water, or had such salient projections, then, with large enough sail, it would sail at least as well as an eighteenth century ship...


"i am not going to argue the point further. believe what you will. plenty of actual info out there on how sailboats work for anyone who wants to know.

as far as chine runers, as used on paradox...they work very well. i have seen tons of videos of paradoxes sailing close hauled; even one in storm conditions chugging along close hauled where most traditional sailboats would have trouble pointing. there is no doubt they work. i doubt they work better that the micro's keel and switching to them would create a ballast placement issue."

- You haven't provided an argument. Sorry. Chine-runners... have you seen a Paradox without? It may surprise just how well one still does. PB&F have talked for yonks of their boxboat design "chine sailing" ability in thin water. Heard of the Mersea duck punt or similar? No foils, no keel, no "chine-runners", and no worries up wind! Perhaps you've heard of the Hobie catamaran...


"adding a small set of well placed and well designed chine runners to the existing set up might help but, it might not."


- It won't. A fence on the chine will only add wetted area drag. It won't add anything significant to the leeway resistance, lateral resistance, of hull and keel as the keel already supplies way plenty. A "chine-runner" configured as a step, not fence, may have a use in a wet reboarding of Micro but a ladder of some sort or rudder endplate would overall be a far better thing... 




---In bolger@yahoogroups.com, <Leighpilot@...> wrote :

i actualy never stated how lift was actually generated. i simply stated that the keel uses lift, and not drag, to resist leeway.  lift is a force generated perpendicular to the direction of motion. drag is a force that acts in the opposite direction of the fow of movement. thus, my examples of drag and lift in my post. 

the usual misuse of Bernoulli was never in my thoughts nor in my post. however there is an element of his theory involved in the generation of lift, just not as it's usually misunderstood. the flow of air on the upper side of the wing is, indeed, flowing faster that that under the wing. much faster than could be explained by the distance the fluid needs to travel across both sides of the foil. and, indeed, as you point out, some planes ( like stunt planes ) have symmetrical foils; which blows that whole idea out of the water.

however, faster moving air does have less pressure than slow moving air. one component in the creation of lift. there are a number. it's not exactly black and white, from the lectures i have watched and the sources i have read. a lot of the incorrect theories are based on misunderstandings of the various elements that create lift. including one incorrect theory based on a misunderstanding of the deflection you mention in your post. 

as far as the compressabiity of water:  

"The compressibility of water is a function of pressure and temperature. At 0 °C, at the limit of zero pressure, the compressibility is5.1×10−10 Pa−1.[32] At the zero-pressure limit, the compressibility reaches a minimum of 4.4×10−10 Pa−1 around 45 °C before increasing again with increasing temperature. As the pressure is increased, the compressibility decreases, being 3.9×10−10 Pa−1 at 0 °C and 100 MPa.

The bulk modulus of water is 2.2 GPa.[33] The low compressibility of non-gases, and of water in particular, leads to their often being assumed as incompressible. The low compressibility of water means that even in the deep oceans at 4 km depth, where pressures are 40 MPa, there is only a 1.8% decrease in volume.http://en.wikipedia.org/wiki/Properties_of_water#cite_note-nave-33 "

the point being, if water was not compressable, you would not need special equipment to deal with the pressure at great depths.


however, i never said anything about the compression of water being the cause of pressure. there is water pressure in your faucet but it is not achieved through compression of the water in the pipes.


the issue of pressure is important, however. lift is a force. that force affects the pressure of the fluid surrounding an object in that fluid. as one lecturer, i watched, pointed out, an object immersed in a fluid is in contact with that fluid on all sides. the fuid is exerting pressure, equally, perpendicular to the object. 

if motion occurs, the pressure on the sides becomes unequal. drag, the force in opposition to the direction of an object's movement, creates higher pressure on the sides of the object it is acting on. lift, the force that is perpendicuar to the motion of the object, reduces the pressure on the surfaces it acts on. with an object immersed in a fluid, if the pressure exerted on all surfaces of the object is equal there can be no chage in motion. a still object will remain still. 


if the force of the wind pushes your boat to starboard, it does so because it creates an imbalance of pressure; in this case, that means the wind increases the pressure on the windward side. if this leeward motion is to be resisted, an equal force, creating an equalization of pressure, must be applied to the boat, in opposition to the force of the wind. 


in my previous example, the boat in motion (which successfuly resists leeway) is doing so due to lift: a force perpendicular to the forward motion of the boat. the stil boat being blown sideways is experiencing drag on it's leeward side. however, as previously noted, that drag does almost nothing to resist the wind blowing against it. thus, the lift (not drag) generated by the keel interacting with the lift generated by the sails is what allows a boat to sail upwind.  how is that not correct?



 





Hi folk

I'm going to chime in at this point as it's finally come around to my own area of expertise and a personal bugbear. 

As a pilot I'm often confronted with pilots who still believe the old canard of the erroneous extrapolation of Bernoulli's Theory in which it's stated that faster airflow ( and lower pressure ) over the upper curved surface of a foil is what caused lift. This is false as the delta P is insignificant and easily disproven by anyone who has ever flown a cheap balsa glider,man aerobatic S300,or an F104 , all of which have symmetrical airfoils. Further more for an underwater foil to create " lift" under this theory , one would have to postulate differential pressure in the water flow around the foil. Water is not compressible so pressure variation are impossible. 

So where does the lift come from? It's the deflected flow of the fluid medium that causes thrust in the opposite direction to the deflected flow. Wolfgang Langewiesche s book Stick and Rudder has the best explanation. 

So what is the function of the foil?  A foil just modifies the drag characteristics of the wing/keel. Decide on the medium your foil will be in, the speed range you'll need, the loads the foil will experience and chose the profile that suits your needs. 

So we can all drop the differential pressure discussion, especially for underwater foils, the ones in an incompressible medium. :). Foils just change drag characteristics. 



Leigh Ross

484-464-1575 (C)



On Jul 23, 2014, at 0:46, "motorcyclejack2@...[bolger]" <bolger@yahoogroups.com> wrote:

 




---Inbolger@yahoogroups.com, <c.ruzer@...> wrote :

Take a look at the component force vectors of sail and keel, or foil, or hull. Keel/foil/hull may resist leeway ie oppose sail side/drag forces with near 100% drag. Heard of drogues, sea anchors, etc? The more immersed area the more drag... The drag near on its own may prevent, that is to say drastically slow, the boat going sideways. Now add some sail force drive vector and away she goes; and even slowly, with mostly pure drag reacting on the keel or foil and hull she may make good an acceptable course to windward. Good sails and good sail handling help!



source info? that goes against any and everything i have ever read, heard, or seen about how sailboats work.

first, drag is how sailboats run down wind. the sail, like your sea anchor or a parachute, has a bely...a 'container' in which to trap the fluid it is moving in. it's much like dipping a cup in a barrel to fill it. the wind (a fluid just like water) is trapped in the belly of the sail and so it can not easily escape and it builds up pressure as it collects in the belly. in a sail, this high pressure pushes the sail through the, comparatively, lower pressure on the other side of the sail. in a sea anchor or parachute, the high pressure greatly slows the anchor or chute's movement through the fluid.

underwater foils, whether they be fin or full keels, and hulls do not have a belly shaped into them. in fact, most hulls and any foil shaped fin is just the opposite, presenting a convex surface to the fluid; not concave like your sea anchor (which is made to trap the water). this means that, while water may meet some drag resistance from  the keel being in the water, it is free to wash around the keel...even moreso a foil shaped fin or the curved side of a hull. this means that, as a creator of drag (to supposedly stop leeway), underwater foils are not very well designed. 

drag works best when the force is perpendicular to the surface it is acting on. that's important to remember. so, let's examine a sail. when you are running down wind, the wind is pretty much perpendicular to the sail.  sailing close hauled, however, there is only enough wind behind the sail (drag) to basicaly keep it's foil shape. barely any drive is drag at that time. the boat is totally lift driven, close hauled.

running is the slowest point of sailing. while a few points above a beam reach is the fastest point of saiing due to the combination of drag and lift, close hauled sailing is stil faster that running. this means that lift is a better driving force than drag.

now, how does that apply to a keel or fin? well, if you sit in your saiboat, on flat water (just to simpify things), perpendicular to a 10kt wind with no sails up, the force of the wind on your hull will be trying to push the boat through the water with the force completely perpendicular to the keel. if you have ever been in such a situation, you will have noticed thatr the wind has no problem doing that at all. in fact, it will push the sailboat just as easily as it woud a row boat without a keel. 

so, in a situation where drag is at it's greatest, leeway is at it's greatest.

now, hoist sail and catch the wind. as the boat moves forward with greater and greater speed, leeway gets less. the faster the boat is moving the more effective the keel is at stopping leeway.

but...wait! when the boat is moving forwards, the force of the water is no longer perpendicular to the keel. in fact, the kee is moving throught the water around 10 degrees away from being paralell to the water moving across it. in other words, drag resisting sideways motion is now very low...but leeway is also very low.

so, let's think about this. while drag production (in a direction to resist leeway) is highest, leeway is greatest. yet, while drag production is lowest, leeway is least.

if your theory is right, a sailboat should be rock steady while it is not sailing and have all kinds of leeway when it is. but it doesn't. that's because the keel/fin works like the sail, only underwater and it creates lift in the opposite direction of the wind. the two forces pinch the boat forwards almost like shooting a watermelon seed from between your fingers. that's lift not drag. the keel can be a lot smaller because water is a lot thicker than air....around 4% of sail area is a good approximation, depending on keel type.

an iceberg has tons of mass under the water creating all kinds of drag, but if you stuck a big sail on one it would never sail up wind; only down wind. that's because the underwater surface of an iceberg isn't shaped to create lift. if it was, you could sail one up wind.

i am not going to argue the point further. believe what you will. plenty of actual info out there on how sailboats work for anyone who wants to know.

as far as chine runers, as used on paradox...they work very well. i have seen tons of videos of paradoxes sailing close hauled; even one in storm conditions chugging along close hauled where most traditional sailboats would have trouble pointing. there is no doubt they work. i doubt they work better that the micro's keel and switching to them would create a ballast placement issue.

adding a small set of well placed and well designed chine runners to the existing set up might help but, it might not. you can only do so much in light airs. and they would create drag ( against forward motion ) to slow the boat because they would add the the wetted surface. 

probably better just to not pinch her in light airs or to feather, if you must squeeze every point to the wind that you can.


I like Leigh Ross’s remarks too. “Deflected flow.” Water pushed aside, pushing back. I think this analysis corresponds to my own thinking which runs on the
“inclined plane” idea from junior high school physics. The water is being deflected by an inclined plane. There is no windward vector to counteract side-way unless the keel or “foil” is inclined to the flow a bit.  This would seem to mean that even in the high speed foiling cats, the foils cannot produce “lift” unless they are at a slight angle to the flow of water past them, in other words that you have to have sideway to have lift. Which also means that you can’t get something for nothing.  Is this right?

 

From:bolger@yahoogroups.com [mailto:bolger@yahoogroups.com]
Sent:Wednesday, July 23, 2014 9:19 AM
To:bolger@yahoogroups.com
Subject:Re: [bolger] Re: Micro with chine runners?

 

 

Thank you !
Our thinking would seem to have followed this line of reasoning.
Susanne Altenburger, PB&F

 

Sent:Wednesday, July 23, 2014 9:04 AM

Subject:Re: [bolger] Re: Micro with chine runners?

 

 

Hi folk

 

I'm going to chime in at this point as it's finally come around to my own area of expertise and a personal bugbear.

 

As a pilot I'm often confronted with pilots who still believe the old canard of the erroneous extrapolation of Bernoulli's Theory in which it's stated that faster airflow ( and lower pressure ) over the upper curved surface of a foil is what caused lift. This is false as the delta P is insignificant and easily disproven by anyone who has ever flown a cheap balsa glider,man aerobatic S300,or an F104 , all of which have symmetrical airfoils. Further more for an underwater foil to create " lift" under this theory , one would have to postulate differential pressure in the water flow around the foil. Water is not compressible so pressure variation are impossible.

 

So where does the lift come from? It's the deflected flow of the fluid medium that causes thrust in the opposite direction to the deflected flow. Wolfgang Langewiesche s book Stick and Rudder has the best explanation.

 

So what is the function of the foil?  A foil just modifies the drag characteristics of the wing/keel. Decide on the medium your foil will be in, the speed range you'll need, the loads the foil will experience and chose the profile that suits your needs.

 

So we can all drop the differential pressure discussion, especially for underwater foils, the ones in an incompressible medium. :). Foils just change drag characteristics.

 



Leigh Ross

 

484-464-1575 (C)

 

 


On Jul 23, 2014, at 0:46, "motorcyclejack2@...[bolger]" <bolger@yahoogroups.com> wrote:

 

 



---Inbolger@yahoogroups.com, <c.ruzer@...> wrote :

Take a look at the component force vectors of sail and keel, or foil, or hull. Keel/foil/hull may resist leeway ie oppose sail side/drag forces with near 100% drag. Heard of drogues, sea anchors, etc? The more immersed area the more drag... The drag near on its own may prevent, that is to say drastically slow, the boat going sideways. Now add some sail force drive vector and away she goes; and even slowly, with mostly pure drag reacting on the keel or foil and hull she may make good an acceptable course to windward. Good sails and good sail handling help!

 

 

 

source info? that goes against any and everything i have ever read, heard, or seen about how sailboats work.

 

first, drag is how sailboats run down wind. the sail, like your sea anchor or a parachute, has a bely...a 'container' in which to trap the fluid it is moving in. it's much like dipping a cup in a barrel to fill it. the wind (a fluid just like water) is trapped in the belly of the sail and so it can not easily escape and it builds up pressure as it collects in the belly. in a sail, this high pressure pushes the sail through the, comparatively, lower pressure on the other side of the sail. in a sea anchor or parachute, the high pressure greatly slows the anchor or chute's movement through the fluid.

 

underwater foils, whether they be fin or full keels, and hulls do not have a belly shaped into them. in fact, most hulls and any foil shaped fin is just the opposite, presenting a convex surface to the fluid; not concave like your sea anchor (which is made to trap the water). this means that, while water may meet some drag resistance from  the keel being in the water, it is free to wash around the keel...even moreso a foil shaped fin or the curved side of a hull. this means that, as a creator of drag (to supposedly stop leeway), underwater foils are not very well designed.

 

drag works best when the force is perpendicular to the surface it is acting on. that's important to remember. so, let's examine a sail. when you are running down wind, the wind is pretty much perpendicular to the sail.  sailing close hauled, however, there is only enough wind behind the sail (drag) to basicaly keep it's foil shape. barely any drive is drag at that time. the boat is totally lift driven, close hauled.

 

running is the slowest point of sailing. while a few points above a beam reach is the fastest point of saiing due to the combination of drag and lift, close hauled sailing is stil faster that running. this means that lift is a better driving force than drag.

 

now, how does that apply to a keel or fin? well, if you sit in your saiboat, on flat water (just to simpify things), perpendicular to a 10kt wind with no sails up, the force of the wind on your hull will be trying to push the boat through the water with the force completely perpendicular to the keel. if you have ever been in such a situation, you will have noticed thatr the wind has no problem doing that at all. in fact, it will push the sailboat just as easily as it woud a row boat without a keel.

 

so, in a situation where drag is at it's greatest, leeway is at it's greatest.

 

now, hoist sail and catch the wind. as the boat moves forward with greater and greater speed, leeway gets less. the faster the boat is moving the more effective the keel is at stopping leeway.

 

but...wait! when the boat is moving forwards, the force of the water is no longer perpendicular to the keel. in fact, the kee is moving throught the water around 10 degrees away from being paralell to the water moving across it. in other words, drag resisting sideways motion is now very low...but leeway is also very low.

 

so, let's think about this. while drag production (in a direction to resist leeway) is highest, leeway is greatest. yet, while drag production is lowest, leeway is least.

 

if your theory is right, a sailboat should be rock steady while it is not sailing and have all kinds of leeway when it is. but it doesn't. that's because the keel/fin works like the sail, only underwater and it creates lift in the opposite direction of the wind. the two forces pinch the boat forwards almost like shooting a watermelon seed from between your fingers. that's lift not drag. the keel can be a lot smaller because water is a lot thicker than air....around 4% of sail area is a good approximation, depending on keel type.

 

an iceberg has tons of mass under the water creating all kinds of drag, but if you stuck a big sail on one it would never sail up wind; only down wind. that's because the underwater surface of an iceberg isn't shaped to create lift. if it was, you could sail one up wind.

 

i am not going to argue the point further. believe what you will. plenty of actual info out there on how sailboats work for anyone who wants to know.

 

as far as chine runers, as used on paradox...they work very well. i have seen tons of videos of paradoxes sailing close hauled; even one in storm conditions chugging along close hauled where most traditional sailboats would have trouble pointing. there is no doubt they work. i doubt they work better that the micro's keel and switching to them would create a ballast placement issue.

 

adding a small set of well placed and well designed chine runners to the existing set up might help but, it might not. you can only do so much in light airs. and they would create drag ( against forward motion ) to slow the boat because they would add the the wetted surface.

 

probably better just to not pinch her in light airs or to feather, if you must squeeze every point to the wind that you can.

 

 

Thank you !
Our thinking would seem to have followed this line of reasoning.
Susanne Altenburger, PB&F
 
Sent:Wednesday, July 23, 2014 9:04 AM
Subject:Re: [bolger] Re: Micro with chine runners?
 
 

Hi folk
 
I'm going to chime in at this point as it's finally come around to my own area of expertise and a personal bugbear.
 
As a pilot I'm often confronted with pilots who still believe the old canard of the erroneous extrapolation of Bernoulli's Theory in which it's stated that faster airflow ( and lower pressure ) over the upper curved surface of a foil is what caused lift. This is false as the delta P is insignificant and easily disproven by anyone who has ever flown a cheap balsa glider,man aerobatic S300,or an F104 , all of which have symmetrical airfoils. Further more for an underwater foil to create " lift" under this theory , one would have to postulate differential pressure in the water flow around the foil. Water is not compressible so pressure variation are impossible.
 
So where does the lift come from? It's the deflected flow of the fluid medium that causes thrust in the opposite direction to the deflected flow. Wolfgang Langewiesche s book Stick and Rudder has the best explanation.
 
So what is the function of the foil?  A foil just modifies the drag characteristics of the wing/keel. Decide on the medium your foil will be in, the speed range you'll need, the loads the foil will experience and chose the profile that suits your needs.
 
So we can all drop the differential pressure discussion, especially for underwater foils, the ones in an incompressible medium. :). Foils just change drag characteristics.
 


Leigh Ross
 
484-464-1575 (C)
 
 

On Jul 23, 2014, at 0:46, "motorcyclejack2@...[bolger]" <bolger@yahoogroups.com> wrote:

 

 



---Inbolger@yahoogroups.com, <c.ruzer@...> wrote :

Take a look at the component force vectors of sail and keel, or foil, or hull. Keel/foil/hull may resist leeway ie oppose sail side/drag forces with near 100% drag. Heard of drogues, sea anchors, etc? The more immersed area the more drag... The drag near on its own may prevent, that is to say drastically slow, the boat going sideways. Now add some sail force drive vector and away she goes; and even slowly, with mostly pure drag reacting on the keel or foil and hull she may make good an acceptable course to windward. Good sails and good sail handling help!
 
 
 
source info? that goes against any and everything i have ever read, heard, or seen about how sailboats work.
 
first, drag is how sailboats run down wind. the sail, like your sea anchor or a parachute, has a bely...a 'container' in which to trap the fluid it is moving in. it's much like dipping a cup in a barrel to fill it. the wind (a fluid just like water) is trapped in the belly of the sail and so it can not easily escape and it builds up pressure as it collects in the belly. in a sail, this high pressure pushes the sail through the, comparatively, lower pressure on the other side of the sail. in a sea anchor or parachute, the high pressure greatly slows the anchor or chute's movement through the fluid.
 
underwater foils, whether they be fin or full keels, and hulls do not have a belly shaped into them. in fact, most hulls and any foil shaped fin is just the opposite, presenting a convex surface to the fluid; not concave like your sea anchor (which is made to trap the water). this means that, while water may meet some drag resistance from  the keel being in the water, it is free to wash around the keel...even moreso a foil shaped fin or the curved side of a hull. this means that, as a creator of drag (to supposedly stop leeway), underwater foils are not very well designed.
 
drag works best when the force is perpendicular to the surface it is acting on. that's important to remember. so, let's examine a sail. when you are running down wind, the wind is pretty much perpendicular to the sail.  sailing close hauled, however, there is only enough wind behind the sail (drag) to basicaly keep it's foil shape. barely any drive is drag at that time. the boat is totally lift driven, close hauled.
 
running is the slowest point of sailing. while a few points above a beam reach is the fastest point of saiing due to the combination of drag and lift, close hauled sailing is stil faster that running. this means that lift is a better driving force than drag.
 
now, how does that apply to a keel or fin? well, if you sit in your saiboat, on flat water (just to simpify things), perpendicular to a 10kt wind with no sails up, the force of the wind on your hull will be trying to push the boat through the water with the force completely perpendicular to the keel. if you have ever been in such a situation, you will have noticed thatr the wind has no problem doing that at all. in fact, it will push the sailboat just as easily as it woud a row boat without a keel.
 
so, in a situation where drag is at it's greatest, leeway is at it's greatest.
 
now, hoist sail and catch the wind. as the boat moves forward with greater and greater speed, leeway gets less. the faster the boat is moving the more effective the keel is at stopping leeway.
 
but...wait! when the boat is moving forwards, the force of the water is no longer perpendicular to the keel. in fact, the kee is moving throught the water around 10 degrees away from being paralell to the water moving across it. in other words, drag resisting sideways motion is now very low...but leeway is also very low.
 
so, let's think about this. while drag production (in a direction to resist leeway) is highest, leeway is greatest. yet, while drag production is lowest, leeway is least.
 
if your theory is right, a sailboat should be rock steady while it is not sailing and have all kinds of leeway when it is. but it doesn't. that's because the keel/fin works like the sail, only underwater and it creates lift in the opposite direction of the wind. the two forces pinch the boat forwards almost like shooting a watermelon seed from between your fingers. that's lift not drag. the keel can be a lot smaller because water is a lot thicker than air....around 4% of sail area is a good approximation, depending on keel type.
 
an iceberg has tons of mass under the water creating all kinds of drag, but if you stuck a big sail on one it would never sail up wind; only down wind. that's because the underwater surface of an iceberg isn't shaped to create lift. if it was, you could sail one up wind.
 
i am not going to argue the point further. believe what you will. plenty of actual info out there on how sailboats work for anyone who wants to know.
 
as far as chine runers, as used on paradox...they work very well. i have seen tons of videos of paradoxes sailing close hauled; even one in storm conditions chugging along close hauled where most traditional sailboats would have trouble pointing. there is no doubt they work. i doubt they work better that the micro's keel and switching to them would create a ballast placement issue.
 
adding a small set of well placed and well designed chine runners to the existing set up might help but, it might not. you can only do so much in light airs. and they would create drag ( against forward motion ) to slow the boat because they would add the the wetted surface.
 
probably better just to not pinch her in light airs or to feather, if you must squeeze every point to the wind that you can.
 
 
Hi folk

I'm going to chime in at this point as it's finally come around to my own area of expertise and a personal bugbear. 

As a pilot I'm often confronted with pilots who still believe the old canard of the erroneous extrapolation of Bernoulli's Theory in which it's stated that faster airflow ( and lower pressure ) over the upper curved surface of a foil is what caused lift. This is false as the delta P is insignificant and easily disproven by anyone who has ever flown a cheap balsa glider,man aerobatic S300,or an F104 , all of which have symmetrical airfoils. Further more for an underwater foil to create " lift" under this theory , one would have to postulate differential pressure in the water flow around the foil. Water is not compressible so pressure variation are impossible. 

So where does the lift come from? It's the deflected flow of the fluid medium that causes thrust in the opposite direction to the deflected flow. Wolfgang Langewiesche s book Stick and Rudder has the best explanation. 

So what is the function of the foil?  A foil just modifies the drag characteristics of the wing/keel. Decide on the medium your foil will be in, the speed range you'll need, the loads the foil will experience and chose the profile that suits your needs. 

So we can all drop the differential pressure discussion, especially for underwater foils, the ones in an incompressible medium. :). Foils just change drag characteristics. 



Leigh Ross

484-464-1575 (C)



On Jul 23, 2014, at 0:46, "motorcyclejack2@...[bolger]" <bolger@yahoogroups.com> wrote:

 




---Inbolger@yahoogroups.com, <c.ruzer@...> wrote :

Take a look at the component force vectors of sail and keel, or foil, or hull. Keel/foil/hull may resist leeway ie oppose sail side/drag forces with near 100% drag. Heard of drogues, sea anchors, etc? The more immersed area the more drag... The drag near on its own may prevent, that is to say drastically slow, the boat going sideways. Now add some sail force drive vector and away she goes; and even slowly, with mostly pure drag reacting on the keel or foil and hull she may make good an acceptable course to windward. Good sails and good sail handling help!



source info? that goes against any and everything i have ever read, heard, or seen about how sailboats work.

first, drag is how sailboats run down wind. the sail, like your sea anchor or a parachute, has a bely...a 'container' in which to trap the fluid it is moving in. it's much like dipping a cup in a barrel to fill it. the wind (a fluid just like water) is trapped in the belly of the sail and so it can not easily escape and it builds up pressure as it collects in the belly. in a sail, this high pressure pushes the sail through the, comparatively, lower pressure on the other side of the sail. in a sea anchor or parachute, the high pressure greatly slows the anchor or chute's movement through the fluid.

underwater foils, whether they be fin or full keels, and hulls do not have a belly shaped into them. in fact, most hulls and any foil shaped fin is just the opposite, presenting a convex surface to the fluid; not concave like your sea anchor (which is made to trap the water). this means that, while water may meet some drag resistance from  the keel being in the water, it is free to wash around the keel...even moreso a foil shaped fin or the curved side of a hull. this means that, as a creator of drag (to supposedly stop leeway), underwater foils are not very well designed. 

drag works best when the force is perpendicular to the surface it is acting on. that's important to remember. so, let's examine a sail. when you are running down wind, the wind is pretty much perpendicular to the sail.  sailing close hauled, however, there is only enough wind behind the sail (drag) to basicaly keep it's foil shape. barely any drive is drag at that time. the boat is totally lift driven, close hauled.

running is the slowest point of sailing. while a few points above a beam reach is the fastest point of saiing due to the combination of drag and lift, close hauled sailing is stil faster that running. this means that lift is a better driving force than drag.

now, how does that apply to a keel or fin? well, if you sit in your saiboat, on flat water (just to simpify things), perpendicular to a 10kt wind with no sails up, the force of the wind on your hull will be trying to push the boat through the water with the force completely perpendicular to the keel. if you have ever been in such a situation, you will have noticed thatr the wind has no problem doing that at all. in fact, it will push the sailboat just as easily as it woud a row boat without a keel. 

so, in a situation where drag is at it's greatest, leeway is at it's greatest.

now, hoist sail and catch the wind. as the boat moves forward with greater and greater speed, leeway gets less. the faster the boat is moving the more effective the keel is at stopping leeway.

but...wait! when the boat is moving forwards, the force of the water is no longer perpendicular to the keel. in fact, the kee is moving throught the water around 10 degrees away from being paralell to the water moving across it. in other words, drag resisting sideways motion is now very low...but leeway is also very low.

so, let's think about this. while drag production (in a direction to resist leeway) is highest, leeway is greatest. yet, while drag production is lowest, leeway is least.

if your theory is right, a sailboat should be rock steady while it is not sailing and have all kinds of leeway when it is. but it doesn't. that's because the keel/fin works like the sail, only underwater and it creates lift in the opposite direction of the wind. the two forces pinch the boat forwards almost like shooting a watermelon seed from between your fingers. that's lift not drag. the keel can be a lot smaller because water is a lot thicker than air....around 4% of sail area is a good approximation, depending on keel type.

an iceberg has tons of mass under the water creating all kinds of drag, but if you stuck a big sail on one it would never sail up wind; only down wind. that's because the underwater surface of an iceberg isn't shaped to create lift. if it was, you could sail one up wind.

i am not going to argue the point further. believe what you will. plenty of actual info out there on how sailboats work for anyone who wants to know.

as far as chine runers, as used on paradox...they work very well. i have seen tons of videos of paradoxes sailing close hauled; even one in storm conditions chugging along close hauled where most traditional sailboats would have trouble pointing. there is no doubt they work. i doubt they work better that the micro's keel and switching to them would create a ballast placement issue.

adding a small set of well placed and well designed chine runners to the existing set up might help but, it might not. you can only do so much in light airs. and they would create drag ( against forward motion ) to slow the boat because they would add the the wetted surface. 

probably better just to not pinch her in light airs or to feather, if you must squeeze every point to the wind that you can.





---In bolger@yahoogroups.com, <c.ruzer@...> wrote :

Take a look at the component force vectors of sail and keel, or foil, or hull. Keel/foil/hull may resist leeway ie oppose sail side/drag forces with near 100% drag. Heard of drogues, sea anchors, etc? The more immersed area the more drag... The drag near on its own may prevent, that is to say drastically slow, the boat going sideways. Now add some sail force drive vector and away she goes; and even slowly, with mostly pure drag reacting on the keel or foil and hull she may make good an acceptable course to windward. Good sails and good sail handling help!



source info? that goes against any and everything i have ever read, heard, or seen about how sailboats work.

first, drag is how sailboats run down wind. the sail, like your sea anchor or a parachute, has a bely...a 'container' in which to trap the fluid it is moving in. it's much like dipping a cup in a barrel to fill it. the wind (a fluid just like water) is trapped in the belly of the sail and so it can not easily escape and it builds up pressure as it collects in the belly. in a sail, this high pressure pushes the sail through the, comparatively, lower pressure on the other side of the sail. in a sea anchor or parachute, the high pressure greatly slows the anchor or chute's movement through the fluid.

underwater foils, whether they be fin or full keels, and hulls do not have a belly shaped into them. in fact, most hulls and any foil shaped fin is just the opposite, presenting a convex surface to the fluid; not concave like your sea anchor (which is made to trap the water). this means that, while water may meet some drag resistance from  the keel being in the water, it is free to wash around the keel...even moreso a foil shaped fin or the curved side of a hull. this means that, as a creator of drag (to supposedly stop leeway), underwater foils are not very well designed. 

drag works best when the force is perpendicular to the surface it is acting on. that's important to remember. so, let's examine a sail. when you are running down wind, the wind is pretty much perpendicular to the sail.  sailing close hauled, however, there is only enough wind behind the sail (drag) to basicaly keep it's foil shape. barely any drive is drag at that time. the boat is totally lift driven, close hauled.

running is the slowest point of sailing. while a few points above a beam reach is the fastest point of saiing due to the combination of drag and lift, close hauled sailing is stil faster that running. this means that lift is a better driving force than drag.

now, how does that apply to a keel or fin? well, if you sit in your saiboat, on flat water (just to simpify things), perpendicular to a 10kt wind with no sails up, the force of the wind on your hull will be trying to push the boat through the water with the force completely perpendicular to the keel. if you have ever been in such a situation, you will have noticed thatr the wind has no problem doing that at all. in fact, it will push the sailboat just as easily as it woud a row boat without a keel. 

so, in a situation where drag is at it's greatest, leeway is at it's greatest.

now, hoist sail and catch the wind. as the boat moves forward with greater and greater speed, leeway gets less. the faster the boat is moving the more effective the keel is at stopping leeway.

but...wait! when the boat is moving forwards, the force of the water is no longer perpendicular to the keel. in fact, the kee is moving throught the water around 10 degrees away from being paralell to the water moving across it. in other words, drag resisting sideways motion is now very low...but leeway is also very low.

so, let's think about this. while drag production (in a direction to resist leeway) is highest, leeway is greatest. yet, while drag production is lowest, leeway is least.

if your theory is right, a sailboat should be rock steady while it is not sailing and have all kinds of leeway when it is. but it doesn't. that's because the keel/fin works like the sail, only underwater and it creates lift in the opposite direction of the wind. the two forces pinch the boat forwards almost like shooting a watermelon seed from between your fingers. that's lift not drag. the keel can be a lot smaller because water is a lot thicker than air....around 4% of sail area is a good approximation, depending on keel type.

an iceberg has tons of mass under the water creating all kinds of drag, but if you stuck a big sail on one it would never sail up wind; only down wind. that's because the underwater surface of an iceberg isn't shaped to create lift. if it was, you could sail one up wind.

i am not going to argue the point further. believe what you will. plenty of actual info out there on how sailboats work for anyone who wants to know.

as far as chine runers, as used on paradox...they work very well. i have seen tons of videos of paradoxes sailing close hauled; even one in storm conditions chugging along close hauled where most traditional sailboats would have trouble pointing. there is no doubt they work. i doubt they work better that the micro's keel and switching to them would create a ballast placement issue.

adding a small set of well placed and well designed chine runners to the existing set up might help but, it might not. you can only do so much in light airs. and they would create drag ( against forward motion ) to slow the boat because they would add the the wetted surface. 

probably better just to not pinch her in light airs or to feather, if you must squeeze every point to the wind that you can.


oops,


By "windmill" I had in mind the typical many bladed farm water pump variety.


Efficiency and fast: The wind is free, and hull speed is all you need.

I'm reminded of the difference between windmills and wind turbines. Both work. The first energized by mostly drag and little lift, the second by mostly lift less a little drag. Both suit their purpose. The turbine extracts more power from the wind. Likewise, a streamlined high aspect ratio keel may resist leeway with less area as it is more efficient at extracting power from the attached and laminar water flow, but a low aspect ratio large area draggy keel can do the job, leeway resistance, just as well on the day only add more sail power through increased sail area or stronger wind, etc to go near as fast and high - hey, not as efficient, but the wind is still free.
Take a look at the component force vectors of sail and keel, or foil, or hull. Keel/foil/hull may resist leeway ie oppose sail side/drag forces with near 100% drag. Heard of drogues, sea anchors, etc? The more immersed area the more drag... The drag near on its own may prevent, that is to say drastically slow, the boat going sideways. Now add some sail force drive vector and away she goes; and even slowly, with mostly pure drag reacting on the keel or foil and hull she may make good an acceptable course to windward. Good sails and good sail handling help!



---In bolger@yahoogroups.com, <c.ruzer@...> wrote :

Nope. What I said, and this "underwater foils can not resist sideways motion without moving through the water; which creates lift." just is not so.

that's news to me. never saw a sailboat that would resist being pushed sideways by current or waves, if it was sitting still in the water. so, i have to ask, since all of the information i have ever read about how sailboats work says the underwater foil creates lift in opposition to the sails (even going so far as to say the rudder works by creating lift) is wrong , how do underwater foils work? 
 
Nope. What I said, and this "underwater foils can not resist sideways motion without moving through the water; which creates lift." just is not so.
Kent,

A couple of thoughts.

Micro's keel houses a significant amount (450 lbs) of lead ballast. The
primary function of ballast is to "sink" the boat to its designed
waterlines. A secondary function, if the ballast is mounted below the
waterline, is to add reserve stability and aid in recovery from a knock
down. If you are going to eliminate the keel from a Micro, you need to plan
on adding ballast inside the boat and even then, the righting effect will be
slightly diminished.

Centerboards, leeboards, dagger boards, and keels (and rudders) all provide
lateral resistance (and wetted surface and cost and construction
complexity). The function of lateral resistance is mostly to keep the boat
from being blown sideways through the water. If the boat is blown sideways
("making leeway") it doesn't matter which way the boat is pointed or how
fast it is going. Progress to windward will be very, very slow. At very slow
speeds (light air), bigger surface area trumps smaller surface area. As
speed increases, boards begin to develop lift and smaller boards (with less
surface area/drag) work well and produce less drag.

Chine runners can develop some lift at higher boat speeds but I believe they
will not be very effective in light air. This is not a function of being "a
few tenths of a knot slower", but a matter of not being able to make
progress to windward because of excessive leeway.

All boats are compromises and Micro is compromised toward the advantages of
a fixed, ballasted keel. This compromise does create difficulties with
trailering and beaching. If you want to see an approach to a keel less
Micro, take a look a Michalak's Musicbox 3 on the Duckworks plans section.
It is not a Micro, but the essay on the boat provides some insight as to the
problems of a keel less Micro.

JohnT


-----Original Message-----
From:bolger@yahoogroups.com[mailto:bolger@yahoogroups.com]
Sent: Saturday, July 19, 2014 11:05 AM
To:bolger@yahoogroups.com
Subject: Re: [bolger] Re: Micro with chine runners?

Hi folks --

Many of you clearly have way more expertise on these issues than me, but
I wonder if this discussion has gone off on a tangent? Chine runners
may be less efficient than a keel in some conditions, but haw much
different will that actually make -- a few tenths of a knot?

People don't build Micros to win races or cross oceans. Chine runners
would probably be quite a bit easier to make than a keel, and they have
some other advantages such as shallower draft, sitting level when the
tide goes out, etc. For many owners, those considerations might be more
important than the performance.

I'm considering building a boat myself, one of these years. I don't
have the discipline to spend years on such a project; I'll gladly trade
off some performance for a boat that's super-easy to build and maintain.
Chine runners look like a good solution in that respect.

Just a thought ...



------------------------------------

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I still stick to my advice  Let the designer design. if you want changes, sk the designer to do them. its possible you might come up with an improvement, but its more likely to be an expensive mistake
 
Leigh Ross


P O Box 574
Kresgeville, PA
18333


1 610 624-1730 (Home)
1 484 464-1575 (Cell)


http://www.unicornkayaks.com

From:"Kent kent@... [bolger]" <bolger@yahoogroups.com>
To:bolger@yahoogroups.com
Sent:Saturday, July 19, 2014 11:05 AM
Subject:Re: [bolger] Re: Micro with chine runners?

Hi folks --

Many of you clearly have way more expertise on these issues than me, but
I wonder if this discussion has gone off on a tangent?  Chine runners
may be less efficient than a keel in some conditions, but haw much
different will that actually make -- a few tenths of a knot?

People don't build Micros to win races or cross oceans.  Chine runners
would probably be quite a bit easier to make than a keel, and they have
some other advantages such as shallower draft, sitting level when the
tide goes out, etc.  For many owners, those considerations might be more
important than the performance.

I'm considering building a boat myself, one of these years.  I don't
have the discipline to spend years on such a project; I'll gladly trade
off some performance for a boat that's super-easy to build and maintain.
  Chine runners look like a good solution in that respect.

Just a thought ...



------------------------------------

------------------------------------

Bolger rules!!!
- NO "GO AWAY SPAMMER!" posts!!!  Please!
- no cursing, flaming, trolling, spamming, respamming, or flogging dead horses
- stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
- Pls add your comments at the TOP, SIGN your posts, and snip away
- Plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA, 01930, Fax: (978) 282-1349
- Unsubscribe: bolger-unsubscribe@yahoogroups.com
- Open discussion:bolger_coffee_lounge-subscribe@yahoogroups.com
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Hi folks --

Many of you clearly have way more expertise on these issues than me, but
I wonder if this discussion has gone off on a tangent? Chine runners
may be less efficient than a keel in some conditions, but haw much
different will that actually make -- a few tenths of a knot?

People don't build Micros to win races or cross oceans. Chine runners
would probably be quite a bit easier to make than a keel, and they have
some other advantages such as shallower draft, sitting level when the
tide goes out, etc. For many owners, those considerations might be more
important than the performance.

I'm considering building a boat myself, one of these years. I don't
have the discipline to spend years on such a project; I'll gladly trade
off some performance for a boat that's super-easy to build and maintain.
Chine runners look like a good solution in that respect.

Just a thought ...
Thanks for all the comments. 
Chris was very negative, but I look at the Micro Navigator and see what can be done with a Micro, even though it is the complete package as is.
I believe that asking questions often gives rise to ideas that would otherwise be missed.





---In bolger@yahoogroups.com, <motorcyclejack2@...> wrote :

in fact, the answer to your problem might be technique rather than structure. in light airs, you feather. fall off a bit to gather way, then point up until you begin to slow down; faling off again to gather way again and repeat the whole process. by making a gracefull S patter through the water, in this manner, you can make good your course to wind in light airs.


---In bolger@yahoogroups.com, <c.ruzer@...> wrote :

".. at slow speed" implies light air, negligible heeling, and is in the speed or power region where wetted area drag matters most for this type of heavy displacement monohull. Why would you add extra hydro drag at all? Chine runners don't "lift" they simply help lower leeway in the right application. Add extra drag and leeway will increase.


i'd have to disaggree about chine runners not creating lift. it's a misunderstanding amongst many sailors that long keels and chine runners don't create lift; that only deep skinny foils create lift. the idea is that long keels and chine runners only resist sideways motion through drag, essentially.

not true. long keels and chine runners do create lift. deep skinny fils that are airfoil shaped are simply more efficient at creating lift. however, centerboards, daggerboards, and rudders that are not foil shaped in cross section still work to create lift; much as the non-foil shaped wings on the wright brother's plane created lift.

if you look at the chine runners on the paradox you will notice that they are semi foil shaped on the upper sides and pretty much flat on the lower sides.

at low heel angles, the chine runners act as end plates and the side of the hull, which is slab sided below the water line, acts as the foil. 

when heeled, the lee chine runner digs in, creating lift. that's why his boats can sail up wind. if the chine runners did not create lift, his boats could not sail to wind.

in very light winds, with negligible headway, no underwater foil creates lift. even a boat with a deep skinny foil cross sectioned fin will be pushed sideways by current or waves if it is not in motion. underwater foils can not resist sideways motion without moving through the water; which creates lift.

to the OP: in very light airs, no vessel points very well. under such conditions, it is best to fall off a bit so that you can make way. it woud be worth trying the chine runners or making the entire keel deeper ( while keeping the same profile ), but you also might not get any improvement at all.it is worth a try but make sure you can undo it if it gains you nothing. 



---In bolger@yahoogroups.com, <c.ruzer@...> wrote :

".. at slow speed" implies light air, negligible heeling, and is in the speed or power region where wetted area drag matters most for this type of heavy displacement monohull. Why would you add extra hydro drag at all? Chine runners don't "lift" they simply help lower leeway in the right application. Add extra drag and leeway will increase.


i'd have to disaggree about chine runners not creating lift. it's a misunderstanding amongst many sailors that long keels and chine runners don't create lift; that only deep skinny foils create lift. the idea is that long keels and chine runners only resist sideways motion through drag, essentially.

not true. long keels and chine runners do create lift. deep skinny fils that are airfoil shaped are simply more efficient at creating lift. however, centerboards, daggerboards, and rudders that are not foil shaped in cross section still work to create lift; much as the non-foil shaped wings on the wright brother's plane created lift.

if you look at the chine runners on the paradox you will notice that they are semi foil shaped on the upper sides and pretty much flat on the lower sides.

at low heel angles, the chine runners act as end plates and the side of the hull, which is slab sided below the water line, acts as the foil. 

when heeled, the lee chine runner digs in, creating lift. that's why his boats can sail up wind. if the chine runners did not create lift, his boats could not sail to wind.

in very light winds, with negligible headway, no underwater foil creates lift. even a boat with a deep skinny foil cross sectioned fin will be pushed sideways by current or waves if it is not in motion. underwater foils can not resist sideways motion without moving through the water; which creates lift.

to the OP: in very light airs, no vessel points very well. under such conditions, it is best to fall off a bit so that you can make way. it woud be worth trying the chine runners or making the entire keel deeper ( while keeping the same profile ), but you also might not get any improvement at all.it is worth a try but make sure you can undo it if it gains you nothing. 
".. at slow speed" implies light air, negligible heeling, and is in the speed or power region where wetted area drag matters most for this type of heavy displacement monohull. Why would you add extra hydro drag at all? Chine runners don't "lift" they simply help lower leeway in the right application. Add extra drag and leeway will increase.

Ya might place wings on the keel. .. or a centreboard ..



"Chine runners" so called are merely a fence sited along the chine, a chine edge projection, between the high pressure leeward side panel and the low pressure relatively deeply curved bottom panel. The lifting body effect formed by the high pressure immersed side and the curvy low pressure bottom and the fence separating them works most the more the hull is heeled. Micro does not heel all that much.

Chine runners will help a lot, especially at low speed. They should be designed to help "lift" the boat to windward. Worth a try, you can always take them off if you don't like the performance.

 

If I were to build a Micro I would also put an end plate over the central part of the keel.

Don't mess with the design unless you're a very experienced sailor or designer. It seldom ends well. 

Leigh Ross

484-464-1575 (C)



On Jul 17, 2014, at 22:37, "motorcyclejack2@...[bolger]" <bolger@yahoogroups.com> wrote:

 

considering that the micro is slab sided, i am prety sure properly desiged chine runners would work. if i was concerned with leeway, though, i might simply opt for a deeper keel. i am assuming you are talking of adding chine runners in addition to the existing keel. 



---Inbolger@yahoogroups.com, <brianincorv@...> wrote :

I have a Micro. I believe that this design is very much a "package", and that changes to it should be considered very carefully.

 

Not that it can't be done:

 

Here is one of Jim Michalaks takes (he's done others), on how to make a shallower Micro-type. His is also quicker to set up. Whether it's better or not, I have no idea.  I have a collection of his plans, and they are economical and easy to follow.

Musicbox2

 

 

 

Here is designer Ross Lillistone's  musing on what makes Micro work:

Ross Lillistone Wooden Boats: Thinking About Phil Bolger's MICRO - Part 2

 

What are chine runners? If they are straight fore and aft, four or five or six feet long, and placed well out toward the chines, I suppose they might resist leeway, but a cost in  wetted surface and turbulence, and I think they could be a vulnerability and a headache, rather like my swinging brass plate mounted on the keel on my Micro. It works well but it probably is still not a good idea

When Micro is making any way to speak of, in light or moderate winds, she does not make much leeway. She may not point within 90 degrees with her sheets started, but she makes good her heading, amazingly well. If anybody’s Micro does poorly upwind, I submit she might be sheeted in too hard—she likes her sprit-boom end just over the bulwarks, not inboard. Or she might not have well cut sails. Or the winds might be too light, or up toward 20, too strong for her when there is a powerful chop.

I just had an afternoon of working up Tupper Lake in a very stiff breeze, such that I put in both reefs in the main (not very well), and I was more than satisfied at the way she marched up past island after island while we sailing her were completely relaxed and the boat only lightly heeled. Why do we amateurs try to improve on this?

Since then I have been studying how best to reef her. I think the key is to do it so that the boom remains at the same height and angle. This means not only bringing down the head of the sail the right amount, but bringing up the tack proportionately, and having a good system for holding the successive clews close to the boom and out-hauling them. And figuring out what to do or not do with the old clew-triangles that have been taken out of play.

Maybe we should have a thread on this subject, which is one where Phil left matters to us!

Mason

From:bolger@yahoogroups.com [mailto:bolger@yahoogroups.com]
Sent:Thursday, July 17, 2014 5:37 PM
To:bolger@yahoogroups.com
Subject:[bolger] Re: Micro with chine runners?

 

 

considering that the micro is slab sided, i am prety sure properly desiged chine runners would work. if i was concerned with leeway, though, i might simply opt for a deeper keel. i am assuming you are talking of adding chine runners in addition to the existing keel. 



---Inbolger@yahoogroups.com, <brianincorv@...> wrote :

I have a Micro. I believe that this design is very much a "package", and that changes to it should be considered very carefully.

 

Not that it can't be done:

 

Here is one of Jim Michalaks takes (he's done others), on how to make a shallower Micro-type. His is also quicker to set up. Whether it's better or not, I have no idea.  I have a collection of his plans, and they are economical and easy to follow.

Musicbox2

image

Musicbox2

MUSICBOX2, CABIN SAILBOAT, 15' X 6-1/2', 800 POUNDS EMPTY  ...its the same as Musicbox3 ...

Preview by Yahoo

 

 

 

Here is designer Ross Lillistone's  musing on what makes Micro work:

Ross Lillistone Wooden Boats: Thinking About Phil Bolger's MICRO - Part 2

image

Ross Lillistone Wooden Boats: Thinking About Phil Bolger...

A little while ago I wrote a preamble in response to a request from Dennis Marshall for comments about Phil Bolger's wonderful Micro design - seehttp://rossli...

Preview by Yahoo

 

considering that the micro is slab sided, i am prety sure properly desiged chine runners would work. if i was concerned with leeway, though, i might simply opt for a deeper keel. i am assuming you are talking of adding chine runners in addition to the existing keel. 


---In bolger@yahoogroups.com, <brianincorv@...> wrote :

I have a Micro. I believe that this design is very much a "package", and that changes to it should be considered very carefully.

 

Not that it can't be done:

 

Here is one of Jim Michalaks takes (he's done others), on how to make a shallower Micro-type. His is also quicker to set up. Whether it's better or not, I have no idea.  I have a collection of his plans, and they are economical and easy to follow.

Musicbox2

 

 

 

Here is designer Ross Lillistone's  musing on what makes Micro work:

Ross Lillistone Wooden Boats: Thinking About Phil Bolger's MICRO - Part 2

 

I have a Micro. I believe that this design is very much a "package", and that changes to it should be considered very carefully.

 

Not that it can't be done:

 

Here is one of Jim Michalaks takes (he's done others), on how to make a shallower Micro-type. His is also quicker to set up. Whether it's better or not, I have no idea.  I have a collection of his plans, and they are economical and easy to follow.

Musicbox2

Just wondering if anyone has thought of putting chine runners on a Micro similar to Matt Layden's Paradox?

Would they reduce leeway at all or just introduce a lot of drag with no benefit?

Just a thought.  Brent