Sheet Angle vs. Force for Various Angles of Incidence
So according to this the maximum force is obtained at different sheet angles for different angles of incidence (angle the centerline of the boat to the apparent wind). The only thing remarkable is that at 25 degrees of apparent wind the force seems higher with the sheet car set back on the track from centerline. Maybe back about 18 inches, or 6 inches forward. The track is 24" long on my boat. Of course you have to look at where the foresail luffs to be sure you don't have the foot too tight when you pull the fairlead back further.