a problem in boomless cats that as you hit a gust, you become overpowered and sheet off, this lets the sail get fuller and more powerful and also gives weather helm. [color:"red"] so what you need to do in a gust is sheet IN ! [/color]
YES! You are the first I've heard say this (except for me). It took me about 3 years to realize this. There is a rapid bad sequence of gust, sheet out, fat main, excess heel,rounding up (like weather helm), sheet out more to depower which slows you down, then foot off to regain speed, often driving bows under. This often repeated sequence is low, slow, and the boat hobby-horses causing weather helm and/or a bow stuff. It also makes people hate boomless boats.
Instead, if you sheet IN (or just hold it) and move weight forward, the bows don't stuff, the boat doesn't heel, and you point higher and increase speed. This is NOT pinching. It's faster and the weather helm and tendency to stuff a bow eases off. Steady speed, no excess steering, higher pointing. Eases pucker factor in high wind gusts as well! <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" /> However, it takes balls of steel to NOT sheet out the first few times you try it in a gust.
Hmmm, don't ever recall that type of action on my 6.0. If over powered letting the main off opened up the top of the sail dumping wind and depowering very nicely. I suspect if dumping the main powers and rounds you up that maybe you weren't trimmed properly to start (over trimmed a bit maybe, or maybe the sheeting angle wasn't set right). Also, the only time I've experienced a boat rounding up like that was either in a monohull or on my H-18 with the molded rudders. On the monohull the rounded shape of the hull itself lends to weather helm when you heel excessively. On the 18 the rudders deflected and boat would skid the stern. If you're getting excessive weather helm helm when overpowered perhaps the rudders are loosing bite, for a variety of reasons. At least upwind. Downwind sheeting can stall the back of the sail and depower things well, and over sheeting the jib can give the same effect - closing the slot and stalling both sails. I guess nobody has asked whether this is an upwind or downwind problem, or a problem all the time.
But just to make sure the terminology is correct here - weather helm is when the boat wants to turn into the wind on its own. Lee helm is when the boat wants to turn away from the wind on its own.
It has everything to do with the balance between the center of effort on the sailplan versus the center of effort of the underwater portion of the boat. Line up the centers of effort and the boat is neutral (my H-20 was this way, downwind it would transition to lee helm if a wave got you just right), sail effort behind the wet effort and the boat will tend to round up giving weather helm, the other way results in lee helm. But again, it's the balance between the hull center of effort and the sailplan's. What's going on with the boat at a particular time can affect that balance.
Sail trim definitely affects this - we know it's easier to turn down if the main is eased, easier to turn up if the main is trimmed. You should be able to steer the boat with sail trim alone.
So, given all that, is it possible raking forward is sinking the bows a bit, effectively moving the wet center of effort forward as well as the center of effort of the sail plan? Maybe, I'd have to see what your boat looks like and how you're sailing it. It could be just that your boat likes the mast forward more and is more powered up, giving you the feeling that helm has increased when maybe you just need to get your rudders raked right. Again, my 18 was like this - mast forward meant more power, and it emphasized the weaknesses in the rudder system. So many variables...
Improperly raked rudders can give the feeling of horrible weather helm, when in reality it's not affecting the balance of the boat that much, but is affecting the effort required on the helm, again giving the feeling that weather helm is bad.
