Our size three blade is the perfect fit for our Mohican, an Epic V10, or an Epic V12. It's the third blade from the right in the photo.
We find that a size three blade is a good compromise between turning agility and drag at most speeds. If a surfski paddler is more concerned about maximum control at slow speeds and in sdverse conditions, a size four or larger (special order) fin may be required.
The blades are made from hard anodized 1/8" 6061T6 aluminum with a milled radius on the leading edge and a bevel on the trailing edge for good lift and low drag. A 4 mm or 5/32" Allen wrench removes the hinge pin for easy removal of the rudder and the blades can be interchanged by removing the spring with the use of a Phillips screwdriver holding the spring retainer.