Adding Stability
Two more things to sand. Canoes generally have a center thwart, something going from one side of the canoe to the other which gives the hull more rigidity. Small solo canoes like this one have the paddler near the center of the boat where a center thwart would be in the way.
To make up for not having a thwart I made the decks a little longer and counted on them and the gunwales to give the boat the rigidity it needed. Another answer is to add these carrying handles at each end which will serve two purposes. They make it easy to carry the boat with another person and they will add stiffness. I made them out of cherry and fastened them with 10-24 carriage bolts glued into the gunwale with nuts and washers underneath the handles. If need be the handles can be removed for re-finishing.