Robert is right; I have seen boats with kicker motors that had no blockage and others that did. It all comes down to just how close the lower unit on the kicker motor, and the main motor, are to the transom of the boat. For the larger HDSi transducers for the 898, 997, 998, 1197 and 1198 units we recommend seven inches of clearance. For the smaller Compact Side Imaging (CSi) transducers of the 797 and 798 units we recommend five inches of clearance between the transom and motor(s).