I would also suspect he means the "Great Loop"--which there are several different routes for. Yes, several C Dories have done the "Great Loop" (up river/canal systems in New York, to great lakes, to Lake Michicigan, down the Illinois, Mississippi, to Tenn, Tom Bigbee Waterway, to Gulf Coast ICW and across "big bend" of Florida, around Florida (or thru the Okachobee Waterway), and back up the ICW. Generally the greatest distance is less than 150 miles on the great Loop. There can be some differences because of damages to marinas due to flooding etc. The Big Bend, is usually crossed in several segments, and this avoids the 170 or so mile direct route across.
From the great loop web site:
"There is a run of 250 miles from Hoppies near St. Louis to Green Turtle Bay in Kentucky. You can get diesel at Cape Girardeau (Upper Mississippi Mile 52). Kidd River Fuel is no longer serving gasoline. Charlie Brown, the owner, says it just is not worth his while, he only had 15 boats stop by this year, and the mandate to add 10% ethanol causes additional problems for him.
http://www.navigationnotes.com/)
A transient dock is in the works at Paducah (Ohio mile 934) which will reduce the leg to 200 miles. The start of that project is waiting environmental clearance.
The next longest stretch is 135 miles on the Black Warrior River from Bobbies Fish Camp (mile 119) to Dog River on Mobile Bay.
Crossing the Gulf of Mexico from Carrabelle to Tarpon Springs is 170 miles but one can make an intermediate stop in Steinhatchee for fuel.
This information was provided by Alan Lloyd, Great Loop Navigation Notes,
www.NavigationNotes.com"
I believe that I heard some information which contradicted that first statement.
By slowing down, one can get a much longer range in any boat--including the C Dory 22.
Skipper Bob guides are a very good place to start on information, as well as the Great loop forum and Great Loop web site.