Wouter-
Thanks for the info. What's a "sliding boom"??
As to the rudders- Check out some of the "A" cat rudders ala Ben Hall's boat or Nils new Nikita (has only one "cheek" to the rudder support with large "bearing" between the single cheek and the rudder!)-
Photos??

Kirt

Kirt Simmons Taipan #159, "A" cat US 48