A keel with a sharper leading edge will stall much quicker in rough water, than one with a blunter leading edge. How sharp is best, depends on how rough the water you are racing in, and the resulting leeway angle.
x2. A sharper keel will also stall more quickly than the blunter foil at the slow SPEEDS of the R22, in my understanding. Keel shape and thickness would be optimized (drag, lift, stall potential) for typical expected boatspeeds.
Glad to hear you are racing your Ranger 22, but that sounds like a tough fleet of competition! At least I have some old Catalina 27's to beat.
I appreciate your support on refreshing the photos of the old templates thread. I chose a shape similar to the 0010 but more of a hybrid 0012 profile at 10% thickness. I found this similar to my keel shape which was butchered over the last 34 years. Launching Sunday so wish me luck. . .
In contrast with the previous description of the J/24 with saggy headstay (light airs?) I believe the R22 prefers a tighter jibstay to point in most wind conditions. I just added a cascade to my backstay adjuster for this reason.
Check that you are getting full hoist on the main as I had a halyard shackle/nicropress that was taking up 1/2" at the sheave. Even so my new main is 1/2" shorter than stock. Replaced headboard shackle with a swage ball shackle (as was original). I get the best point with boom on centerline (traveler up). Follow the North Trim prescription--speed first, then point.
BTW I found that there is an online loft that has a new 150 genoa that would fit this boat at a very reasonable price. PM me for details.
You might find some helpful feedback by much more experienced R22 racers on the Yahoo Group mailing list.