anti vortex board

[vanvan450]

ANY ONE WITH A CATAMARAN WITH ANTI WORTEX PLAN BOARD , BERN KOHLER STYLE,,http://www.ikarus342000.com/Antivortexp.pdf

[belizesailor]

Never encountered them on cats, but there are of course many "winged" keels and rudders out there, just not common on cats...theory is the same though and should work.

[vanvan450]

please read first the article,,,,, before writing,,,

[barnakiel]

I have seen these on many monohulls. Can't remember any on cats though.

b.

[belizesailor]

Originally Posted by barnakiel

I have seen these on many monohulls. Can't remember any on cats though.

b.

Aparrently you dont follow instructions well either. [emoji1]

[barnakiel]

Ooooppss. Yes ;-)

b.

[mikereed100]

OK, I read the article (Sort of, I looked at the pictures). People were sticking these on Wharrams for a while in an effort to increase weatherliness, but, if I recall, they did not work out so well in practice and the added wetted surface was not worth it.

[vanvan450]

BERN KOHLER SAYS , I COULD SAIL AS CLOSE TO THE WIND AS MONOHULL WITH HIS 11 METERS CATAMARAN PELICAN (WITH ANTI WORTEX PANEL),,, ANY ONE WITH AN EMAIL FOR BERN,,,, AND WE COULD HAVE HIS OPINION,,,,

[BobHorn]

In case nobody noticed, but the name is Bernd, not Bern

[mikereed100]

A lot of cats will sail as close to the wind as a monohull without anti-vortex panels. Was the boat built with anti-vortex panels or did he add them later? If he added them later and noticed an improvement in performance, that would be significant. If the boat was launched with them, then there is no way of knowing whether the panels helped or hindered performance.

[belizesailor]

Originally Posted by vanvan450

BERN KOHLER SAYS , I COULD SAIL AS CLOSE TO THE WIND AS MONOHULL WITH HIS 11 METERS CATAMARAN PELICAN (WITH ANTI WORTEX PANEL),,, ANY ONE WITH AN EMAIL FOR BERN,,,, AND WE COULD HAVE HIS OPINION,,,,

Many cruising cats already sail as close to the wind as many cruising monohulls. There are a lot more factors involved than just "anti-vortex" panels.

My cat easily sails at 40-45d AWA, and will pinch to about 30, perfectly acceptable for a cruising boat and comparable to many cruising monos. My Hobie 33 (racing mono) will sail at 28d AWA (yep, 28!)....no matter how I mod the keels of my cat, it wont ever do that.

Sea state affects cats and monos very differently too in terms of the sailing angle they can actually make good, regardless of angle they can sail to the wind.

[a64pilot]

I know a little about aerodynamics, just a little.
Are they talking about end plates and calling them anti vortex boards?
If so end plates were pretty fashionable in the 1930’s, yet you haven’t seen them for almost 100 years.
However you see them on race cars where the aspect ratio of the wing is severely restricted.

I assume you put these things on the keels? Being a fully symmetrical airfoil, how much lift does a keel generate? I would assume nearly zero as it has pretty much a zero angle of attack? If it’s not generating lift, then there is no difference in pressure, and therefore no vortex.

[Snowpetrel]

Check out Mat Laydens chine runner concept as used on paradox, Same basic idea. Ive seen one of Bernds catamarans sailing down here, seems to go very well.

I put an delta shaped end plate on SnowPetrel1's rudder. Certainly improved control, and I think speed.

[a64pilot]

I would assume most performance boats keels and rudders are elliptical, like the Supermarine Spitfire? If so an elliptical wing tip is much more effective at reducing drag from wing tip vortices than an end plate.
However it wasn’t the go to wing planform for military aircraft due to it being harder to build with higher parts counts and therefore more expensive and lower production rates or you would have seen it more often.

[model 10]

These are not end plates they are winglets. Every new jet has them.