When we first got our Nordic we thought a "whale tail" would really help it out. After looking around at EVERYTHING that I could find I just came to the conclusion that nobody makes a good one. We had 6 or 7 plates CNC Machined and custom bent in different directions. We tried every kind of trial from plane time to top speed with all 7 plates and finally found one that really works well. In my opinion this is the only way to get one that is going to work for your boat. If you have the extra time and $$$$ I could probably figure something out for you.
RiverDave.