Depending on the size of the rudder(s), you may get more effective steering from dual rudders. It comes down to position of the rudder and the size of it. The height being more important than the width of it/them. Generally, the bigger and heavier the boat the larger the rudder(s) need to be. I put dual rudders on my ground-capable airboats. Most of my boats are water only, so only a few have air rudders.