This is the classic boat of the United States Canoe Association (USCA). The width-length formula has been worked out to keep the class competitive. Also, no double blades or rudders. Generally speaking, the skinnier the boat, the faster it is. If you don't like being limited by the specifications of this class, then you might prefer Tandem Unlimited.
Teams may use either one of two canoes.
Competition Cruiser: (4/32) Maximum length 18'6", minimum width 14 3/8% of length at the 4 inch waterline, Minimum bow height 15.5", minimum stern height 11.5", depth at center 11.5". Limited to two entrants with single blade paddles (no rudders).
Pro Boat: (3/27) Maximum length 18'6", minimum width 27" at the 3" waterline. Minimum bow height 15", minimum stern height 10", minimum depth at center 10", minimum gunwale width 33". Limited to two entrants with single blade paddles (no rudders).