Would that be the good "Captain Cicero
With the high performance fins you mention, would this issue (poor tracking, rapidly "going off course") relate more to the rudder design/placement and overall weighted balance of the boat, than the fin keel itself? Going back to the "feathers on an arrow" design idea, I found this in Coles' "Heavy Weather Sailing (6th ed., 2008, rev., Peter Bruce, "Yacht Design and Construction for Heavy Weather," p. 8):
"Small wetted area carries with it advantages that have resulted in the almost universal adoption of the short keel and separate rudder. Comparatively [to various full keel designs, just discussed] it means equal performance with less sail area, especially in light weather, or to windward when speeds are low. Using a short keel the required position of the ballast dictates the location of the CLR [center of lateral resistance]. This disadvantage can be lessened by locating disposable weights as far forward as possible, permitting the ballast keel to come aft, but such gains are limited and the best available strategy to move the CLR aft seems to be to use a large skeg and rudder. These serve the function of feathers on an arrow. Most new boats follow this pattern and, if the ends are balanced, they can behave well, exhibiting no loss of steering control, ability to heave-to or other good seagoing characteristics."
What do you think? A "large skeg and rudder" hardly sounds like most newer production designs!?
Some of the high performance fins....you can barely look down long enough to pick up your coffee with out going off course. My full keel was outfitted with a self-steering vane which was removed because the boat will sail for days on end with a lashed tiller.
My boat is 30loa, 25lwl, 8'9"beam, 5' dafft about15,000lbs....deepest point is at the base of the rudder post (transom hung rudder with slight rake to transom).