Another thing, if the wind is strong that’s means that the boat speed is high, If the boat speed is high a smaller rudder surface will be OK since the lift is proportional to the speed.
Catamaran use very small rudders
Changing the rudder surface modify the CLR position !
ClaudioD
Alan -
to add to Claudio’s comment about catamaran and small rudders, on my cats over the years, I found that by making my rudders adjustable, I could almost dial in as much or little weather helm as wanted or needed. My rudders were set up to allow the tip of the rudder to be adjusted forward or aft by a total amount of 6 inches 3 inched +/- in a rudder leading edge length of approximately 28 inches. The adjustment allowed my rudder tips to be positioned under the hull transom - or raked aft, by the means of a bolt at rudder head that was adjustable with a large stop nut to hold it in place. As the tip of the rudder was moved forward, there was less weather helm, while moving it backward there was more weather helm. Since the rudders would kick-up if they hit something or run aground, when they were extended toward the rear and not down, weather helm was so strong it was difficult to steer at all - the boat rounding up into the wind quickly - and hard. This usually happened when launching from beach where you couldn’t put rudders down.
Going to your photos, the raked back rudder “should” have produced more weather helm and if raked slight forward, lee helm should have been observed. The fact we sailed with two hulls versus one really has no bearing. Also as Claudio noted, sheeting the jib and leaving main loose also helped eliminate the weather helm when leaving the beach. Any main sheeting just added to overall weather helm if boards and rudders weren’t locked down.
Just my experiences in rudder rake - it didn’t take much to make a difference.
Dick
ADDED: Sorry - this has nothing to do with carbon hulls and receiving radio signals.
Well, I jumped in and bought the Graupner… Just waiting for it to arrive from Germany. So I can join the 2.5ghz club…
On the lee/weather helm issue - I would expect to be able to adjust the settings to induce lee helm, just don’t expect it to be fast. If you cannot then maybe the CoE is too far aft, or the CLR is too far forward, and something should be done if a “Neutral” balance cannot be achieved at all. After re making the sails, your next move is drastic and you are shifting the mast or keel.
My understanding of raking the rudder differs from Dick… As you rake the rudder aft, the CLR moves aft with it, reducing weather helm… It’s a little cheat to help get the CLR as far back as possible on an IACC…
Hi Jim - couldn’t find the exact article to support my above opinion, however this is taken from a NACRA5.8 forum regarding correcting lee helm when on port tack. Keep in mind, we have two rudders, and when sailing on one hull, it is the hull with the “pressure” on it that has to have adjustments made. Thus when on Port tack, the starboard rudder is an issue - or when on Starboard tack the port rudder is the one to be balanced correctly.
[i]" … this is a rudder rake issue. We did the Worrell 1000 on a Nacra 5.8 so we had a little time to play with rudder rake regarding lee helm. The tip of the starboard rudder is too far forward wen you have lee helm on port tack. With the little nylon screw backed out a bit more you should be able to balance the helm.
Recently I started racing a new Nacra 20 out of the box. 1st time across the bay, the boat wanted to round down and jibe on port tack if you put the helm down for a second. Starboard tack was balanced. With just a little more aft rake in the starboard rudder adjusted in, the boat balanced right out. It’s amazing what a difference 1/4 inch of rudder rake will make in helm feel on these beach cats."
[/i]I will concede however that cat rudders are “normally” transom mounted, whereas Alan’s rudders are under the hull.
Dick 
Hi Dick
Just to add, There is less need for lead (CoE ahead of CLR) on a Cat, due to the high lateral shift of balance between hulls, which is why a small adjustment makes a big difference.
Monohulls, have a much bigger lead and the rake of the rudder has less of an effect in this area.
Jim