I have not seen any data on what Bernd Kohler has done. I do know hulls do not make efficient leeway preventers. Adding a small plate is not going to improve it much.
Large lateral area is useful in a marina to slow sideways drift at manoeuvring speed but large area involves high drag once sailing. Once moving a high aspect board (or rudder) is a much more efficient way to generate lift to counter leeway. Modern high performance multihulls are making use of cambered boards to prevent leeway thereby avoiding induced drag on the hull. Some monos have rudders forward or keel trim tabs to generate lift without leeway.
A cambered board is the most efficient for a proa because it can be made bi-directional with relatively sharp edges because it should be designed to operate at zero AoA when the boat achieves best VMG. There will be a little positive leeway when pinching up and negative leeway if sailing low and raised once reaching.
Rick
On 27 Mar 2019, at 2:10 am, StoneTool owly@ttc-cmc.net [harryproa] <harryproa@yahoogroups.com.au> wrote:Rick:Have you read Bernd Kohler's article on his antivortex panels? http://ikarus342000.com/Antivortexpanels.htm The functionality of these seems to be contingent on having a sharp edge flat bottom. They have proven unsatisfactory on the KD 860, (8.6M LWL CWL 3000kg), but seem to work well on his much larger Pelican ( 11.5M LWL CWL 4200kg)....or so it is claimed.Assistance in resisting leeway via something like the AV panels or even chine runners via passive structures that do not contribute to draft would seem a desirable feature ....H.W.
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Posted by: Rick Willoughby <rickwill@bigpond.net.au>
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