Better yet a single sculling oar. It will let you navigate in tight spaces better than a set of oars and will work on just about any boat without modifying the boat much if any. But a "real" sculling oar, not just one out of a set of rowing oars.
How to Scull , Yuloh a Boat
a.b.b. - amateur boat building - howto Japanese sculling oar
Newport 17 - "Kohanna"
At sea Darwin's hypotheses is the final arbiter of right of way.