I noticed quite a bit of weathercocking when paddling the Safari. Is it the hull design? I did notice that it can turn on a dime.
I was thinking about what you call weathercocking in the Safari. From what you say, I think you mean the side-to-side movement of the bow as a reaction to your paddling. Because the Safari is short — only ten feet — this is a natural tendency even with the fin installed. This bow-wag can be minimized by modifying your paddle stroke to have a more vertical entry and exit; less of a sweep stroke. Longer rigid kayaks have considerably longer keels and can tolerate almost any kind of paddle technique and not have bow-wag.
The Czechs who make these boats are pretty adept paddlers, and the folks with whom I have paddled use much more vertical strokes. Because of this they didn’t think the Safari needed a tracking fin! Because of my touring experience I had real trouble making the Safari go in a straight line without the fin, but I later got the hang of it. The tracking fin makes a huge difference in bow-wag.
Try experimenting with some different stroke techniques. Here’s a link for tweaking paddling technique: http://www.roguepaddler.com/tweak.htm