A painter is a rope that is attached to the bow of a dinghy, or other small boat, and used for tying up or towing.
Ideally, the length of the painter should be no longer than the length of the boat, especially on small craft, to prevent fouling the propeller of an outboard engine.
Canoeing
Canoes being used in moving water or whitewater are rigged with a painter at both the bow and stern. In addition to the functions mentioned above, a canoe's painters can be used for lining the boat down difficult sections, self-rescue, and boat recovery.
References
Painter (rope) Wikipedia(Text) CC BY-SA