In short. The Grand Union Canal runs 137 miles from London to the Birmingham suburbs, the Canal & River Trust says, with 158 locks. The Trust puts a non-stop trip at about 74 hours. This guide is for the boater: the route, the branches, the two long tunnels, the boat sizes the Trust publishes and the Hatton and Foxton lock flights.
The Grand Union Canal at a glance
| Fact | What the Canal & River Trust says |
|---|---|
| Length | 137 miles, London to Birmingham |
| Locks | 158 |
| Non-stop cruising time | About 74 hours |
| Blisworth Tunnel | 3,075 yards (2,811 metres), about 1.7 miles |
| Hatton flight | 21 locks |
| Grand Junction Canal fully opened | 1805 |
| Renamed the Grand Union | 1929 |
Sources: the Trust's pages on the Grand Union Canal, boating it and its history, and its fascinating facts page (the 74 hours), read on 29 September 2026.
The main line and its branches
The main line links London to Birmingham. Off it run the branches the Trust lists: the Leicester Line (with the Welford Arm), the Aylesbury Arm, the Market Harborough Arm, the Northampton Arm, the Paddington Arm and the Slough Arm.
The two long tunnels
The Trust names the tunnels at Blisworth and Braunston, and the deep cutting at Tring summit, as the Grand Junction's main engineering works. Blisworth is 3,075 yards long and, the Trust says, the third longest navigable tunnel on its network after Standedge and Dudley. The Trust's booking rules are written for wide-beam boats. It says all wide beam boat passage through Braunston Tunnel must be booked in advance so the tunnel can be closed to other boat traffic, and gives the same rule for Blisworth. Wide-beam passage is on Tuesdays and Thursdays, for up to four boats, two in each direction, and has to be booked 48 hours ahead, online or through its regional team. At Braunston the Trust adds that other days may be possible depending on volunteer availability; at Blisworth it says Tuesday and Thursday only. It puts a wide-beam transit at about 45 minutes. Read on 29 September 2026; check the current rules on the Trust's page before you plan a day around either tunnel.
How big a boat fits
The Trust publishes maximum boat dimensions for each stretch, and they change along the route. These are its published maxima, not a promise of what every boat can do on every day: depth in particular varies, as how deep is a canal explains. Check your own boat's figures against each row.
| Stretch | Length | Beam | Draught | Headroom |
|---|---|---|---|---|
| Main line: Brentford to Bulls Bridge | 21.95 m (72 ft) | 4.27 m (14 ft) | 1.3 m (4 ft 3 in) | 2.67 m (8 ft 9 in) |
| Main line: Bulls Bridge to Berkhamsted | 21.95 m (72 ft) | 4.27 m (14 ft) | 1.1 m (3 ft 7 in) | 2.67 m (8 ft 9 in) |
| Main line: Berkhamsted to Long Buckby | 21.95 m (72 ft) | 3.81 m (12 ft 6 in) | 1.17 m (3 ft 10 in) | 2.67 m (8 ft 9 in) |
| Main line: Long Buckby to Camp Hill Locks | 21.95 m (72 ft) | 3.81 m (12 ft 6 in) | 1.17 m (3 ft 10 in) | 1.9 m (6 ft 3 in) |
| Main line: Camp Hill Locks to Digbeth and Salford | 21.69 m (71 ft 2 in) | 2.13 m (7 ft) | 1.17 m (3 ft 10 in) | 2.44 m (8 ft) |
| Leicester Line: Norton Junction to Foxton (narrow) | 21.79 m (71 ft 6 in) | 2.12 m (6 ft 11 in) | 1 m (3 ft 3 in) | 2.28 m (7 ft 6 in) |
| Leicester Line: Foxton to Kings Lock | 21.95 m (72 ft) | 3.05 m (10 ft) | 1 m (3 ft 3 in) | 2.23 m (7 ft) |
| Leicester Line: Kings Lock to Leicester | 24.1 m (79 ft) | 3.05 m (10 ft) | 1 m (3 ft 3 in) | 2.13 m (7 ft) |
Two notes the Trust prints beside the figures: "Pinch point: 14ft Lock S. Leighton Buzzard" on the Berkhamsted to Long Buckby stretch, and between Bridge 22 (Bridleway) and Bridge 60 (Blue Bridge) near Long Itchington, "the maximum beam for navigation is reduced to 12'". Source: the Trust's waterway dimensions page, read on 29 September 2026.
Hatton and Foxton
Hatton is a flight of 21 locks that opened in December 1799 as part of the Warwick & Birmingham Canal and was widened in the 1930s. On the Leicester Line, Foxton Locks is a Grade II listed site and, in the Trust's words, home to the longest staircase flight of locks in Britain. It opened on 9 August 1814, and its inclined plane, opened in 1900, lasted only ten years.
A short history
The Grand Junction Canal was authorised by an Act of 1793 and fully opened in 1805. In 1894 it bought the canals that now make up the Leicester Line. In 1929 the Regent's, the Grand Junction and the two Warwick canals merged and were renamed the Grand Union Canal, and a modernisation scheme was completed in 1937.
Check before you go
The Trust says that if you are planning a boat journey, "it's a good idea to check if there are any closures or works affecting your route" before you leave. Its notices and stoppages page is where they are listed, so that is the place to look on the day, not this guide.
You need a licence for any of it
The Trust is clear that all types and sizes of boats, with or without a motor, need a licence. What one costs is in our narrowboat licence cost guide. Depths and headroom on this canal are in how deep is a canal.
If the boat lives on the Grand Union
The route line of our personalised narrowboat name print takes up to 60 characters, enough for "London & the Grand Union" or "the cut, anywhere". Type the boat's name and the line, and the preview shows the finished layout before you pay.
Written by Craig Fearn, Narrowboat Gifts. Last updated .
