Most of your dimensions and conditions will have little effect on the baffle load.  The baffle should be designed to handle the maximum torque that can be delivered by the motor (2 hp) at the operating speed (420 rpm).  The torque calculation can be done as 63025 * (2 hp) / (420 rpm) = 300 in-lbs = 34 N.m.  With the baffle located 600 mm (0.6 m) from the centerline, it must be able to handle the full motor torque or 57 Newtons force.
 
Worst case for the baffle is if all of that force is applied at the end of the baffle.  Realistic case is if that force is distributed over the submerged length of the baffle.

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