Allagash Waterway
Allagash Waterway Regulations.
http://www.maine.gov/doc/parks/programs/history/allagash/allagashrules.htm
A canoe is defined as a form of small watercraft long and narrow, sharp on both ends or sharp on one end and blunt at the other, usually propelled by paddles or small motors and having no sails. The width at the widest point shall not exceed 20% of the craft’s overall length, nor shall the transom, if any, exceed 26 inches in width. Measurement shall be the outside of the hull but shall not include gunwales, rub rails, or spray rails, if any.
I don't believe rudders are allowed either (one source I found says no, and other sources don't mention them).
http://www.maine.gov/doc/parks/programs/aww/awwcanoe.html
USE OF WATERCRAFT
A. From the south end of Telos Lake to the north end of Chamberlain Lake, the use of all models of personal watercraft (PWC), hovercraft, airboats, racing boats, and pontoon boats is prohibited.
B. From Lock Dam Stream, where it enters Eagle Lake north to Twin Brook Rapids, only canoes without motors or motors not exceeding 10 H.P., may be used on the watercourse.
C. On Allagash Lake and Allagash Stream to the red posts at the entrance of Chamberlain Lake, all watercraft are prohibited except canoes without motors.
D. Except on Telos and Chamberlain Lakes, the use of inflatable watercraft is prohibited.
E. Water skiing or other activities in which individuals are towed behind watercraft are prohibited .