What kind of boat was this??? If the rudder was large enough and the keel small enough in area, the CLR could have shifted forward enough that a large genny would give weather helm. That would probably be the case on Gui's boat if he lost his rudder, since the fin keel on his boat is really just a thin strut supporting a bulb...rather than a keel with any real surface area.
It was a fairly modern (2001), wing keel, production boat. Built in the U.S.
Don't want to name it though.