You did not mention what type of boat, or drive. But if I assume you are talking about a larger cruiser and an inboard: The biggest change will of course be that you loose the ability to use the twin motors to provide some level of low speed steering and maneuverability. But to counter that, often single screw boats have larger rudders and as a result you gain a lot of capability in being able to use that rudder and 'prop wash' to push the back of the boat around. Single screw does take a little more thinking and planning, and there are some things you can not do with 1 prop that you can with two (like crabbing sideways). However in my case I have two effects that I use all the time when piloting: 1) Prop Wash over the large rudder. With this I have the motor in N, put the helm hard over to Port or Sta, and then put the motor into Forward. I then give the throttle a goose and pull it back and then put trans into N. This happens in perhaps 2-3 seconds. Doing this I can push the aft of my boat 3-4 feet at a time and because the time is so short there is little if any headway made. 2) Prop Walk in reverse. When I place my motor into reverse and again Goose the throttle, the stern will move sideways due to 'Prop Walk'. In my case I get about a 2' movement to Port. These two characteristic tend to be more pounced in a single engine boat then a dual because a single engine boat tends to have a larger prop as well as a larger rudder. Another thing I tend to use is spring lines to shore and then using power and a fender I can push the bow or stern will out from a dock if needed. This is helpful when I need to leave a dock where the current is pushing me into it. With a little practice and thinking, one can handle a single screw boat just as well as (if not better :-) then a typical dual motor captain. Have fun!