Rudder "winglets"

I am the owner of a New England style Catboat. They are known for their shallow draft and barn door rudders. I read a recent article discussing the potential merits of a panel at the bottom of these shallow and long rudders to reduce the weather helm. I envision something similar to the "winglets" used on aircraft wings to reduce wing tip turbulence. Any thoughts on the effectiveness of such a concept? Is anyone doing something similar?

 

theres an article here: http://www.oossanen.nl/main/onlineart.html called "reducing draft on large sailing yachts" which mentions application of winglets on rudders. Maybe its an answer to your question.

Pedro.