One leg sets the number. And the way most people calculate their range is the reason they get it wrong.
Everywhere else, fuel is close enough that it manages itself.
The longest stretch without a fuel stop on the Great Loop runs from Alton, Illinois, on the Upper Mississippi, to Paducah, Kentucky. AGLCA gives it as roughly 240 to 250 miles depending on where you read it. Plan for 250 and you're covered.
A boat that can't make 250 miles isn't disqualified. AGLCA's own guidance names the fix: Loopers whose boats don't have the range carry extra fuel on deck in cans, drums or bladders for that one section.
So failing this number fails a 250-mile leg, not the Loop. Worth knowing before you rule out a boat you otherwise like.
This is where most people go wrong, and it isn't obvious.
A boat has two speeds that are efficient, and they're far apart. One is at or near hull speed — usually somewhere around five to eight knots depending on the boat. The other is on plane at the minimum revs that will hold her there. The second burns much more fuel but gets you there sooner.
⚠️ The expensive place is the gap between them — too fast to be a displacement boat, not fast enough to climb onto a plane, pushing a wall of water. Boats spend a lot of fuel in that trough and their owners often don't realize it.
One owner put the trade-off plainly: she did best at seven knots, and keeping her on plane wasn't something he could afford.
So when you see a range figure on a listing, ask what speed it assumes. The same boat can honestly be quoted at wildly different ranges, and the difference is what she was doing at the time.
Anchoring, and not optionally. There are long stretches on the inland rivers with no marinas — AGLCA is direct about it: unless you have a fast boat, anchoring will be required on the Upper Mississippi and on the Tenn-Tom.
And on the Tenn-Tom, the major marinas cap stays at two nights during the main migration season, so that everyone coming behind you has somewhere to tie up. Call ahead if you want longer.
AGLCA's published route-segment pages and FAQ for the distance and the deck-fuel workaround, and boat owners for the two-efficient-speeds point. We haven't measured anyone's fuel burn — the distance is AGLCA's figure and the rest is what owners report from running their own boats.
If we've got something wrong, tell us and we'll fix it — support@caniloop.net. A correction from someone who has actually run it is worth more than anything we can write.