the worst case design condition was taken as hull speed (or slightly higher) and rudder stalled. The same was assumed for the steering gear. This was done both by the NA, Edson, and Whitlock. Maximum torque on the post estimated at 900 ft lbs. I built it and the steering gear for a max torque of 6000 ft lbs. The rudder post was spec'd to be a thick wall stainless tube, calculated yield about 160,000 inch pounds, we built it with a rectangular carbon tube, calculated yield of about 800,000 inch pounds in the weak direction and 1,200,000 inch lbs in the strong direction. The price for this upgrade was negligible, far less than 1% of the cost of the boat.