Which Tohatsu 50 is it ? M-50, MW-50, Everun 50 MX-50, MW-X50, or TLDI MD-50 ? This is not a wild guess, full wot on flat no wind waters with a tach and check max rpm achieved, then reduce pitch to increase rpm if needed, increase pitch to decrease rpm. Each engine has it's own min, max wot parameters.
4 blades are good to power heavy noats or boats which drags too much like pontoon type, don't know if good for thundercats, surely a knowledgeable samaritan will chime in...