At Widcombe, a short flight of locks raises boats from the river just south of Pulteney Bridge into the city and on toward Sydney Gardens. For canal people the star is Bath Deep Lock (numbered 8/9): nearly twenty feet of chamber, created when two locks were merged during restoration. This page is a heritage location note for Bolinder fans — engineering story, honest video curation, and lock craft that matches direct-reverse hot-bulb engines.
| Names | Bath Locks / Widcombe Locks |
|---|---|
| Waterway | Kennet and Avon Canal |
| Place | Widcombe, Bath, Somerset (grid ST756643) |
| Rise | About 57 ft (17.4 m) over roughly half a mile |
| Locks now | Six (originally seven; Deep Lock = old 8 + 9) |
| Bath Deep Lock | About 5.92 m / 19 ft 5 in — Britain’s second-deepest canal lock |
| Access | Towpath; short walk from Bath Spa station via Halfpenny Bridge |
The flight
From the River Avon, boats enter Bath Bottom Lock (No. 7) and climb through the city toward Sydney Gardens. Numbering still remembers the old seven-lock arrangement: after Bottom Lock comes Deep Lock, numbered 8/9, then Wash House (10), Abbey View (11, Grade II listed), Pulteney (12) and Bath Top Lock (13).
| No. | Name | Notes |
|---|---|---|
| 7 | Bath Bottom Lock | Junction with River Avon; side pound and pumping |
| 8/9 | Bath Deep Lock | Merged 1976; ~5.92 m depth |
| 10 | Wash House Lock | Busy mid-flight chamber |
| 11 | Abbey View Lock | Grade II listed |
| 12 | Pulteney Lock | Name links to the nearby estate / bridge |
| 13 | Bath Top Lock | Into Sydney Gardens and short tunnels |
Why Deep Lock is deep
While the canal was derelict, a road (A36 corridor) was built across the site of the lower chamber. When the flight was restored, engineers merged locks 8 and 9 into a single deep chamber (completed 1976). The result feels more like a stone shaft than an ordinary cut: long gate beams, a long fill and empty cycle, and walls that swallow a full-length narrowboat. The Canal & River Trust still promotes the chamber as a photogenic film location.
Depth ranking: about 19 ft 5 in (5.92 m) makes it Britain’s second-deepest canal lock. Deeper still is Tuel Lane Lock on the Rochdale Canal. Bath Deep is often discussed as the deepest narrow lock on CRT waters — useful nuance when someone casually says “the deepest lock.”
Water, pumps, and listed fabric
Bottom Lock has a side pound and pumping station to replace water used each cycle — vital on a busy urban flight. Further pumps serve the upper locks. Above Top Lock the canal threads Sydney Gardens through short tunnels, including the Grade II* Cleveland Tunnel under Cleveland House, once headquarters of the Kennet and Avon Canal Company: industrial HQ literally over the navigation.
Volunteer and British Waterways work revived the locks from the late 1960s; the wider canal’s ceremonial reopening is associated with HM The Queen in 1990.
Video — at Bath
These clips are excellent for place and atmosphere. We do not claim the craft shown are Bolinder-powered unless the uploader says so. Engine type is usually modern diesel.
Video — Bolinder sound and lock craft
Many Bolinder installations reverse by changing engine rotation rather than using a modern gearbox. Reverse can be unreliable when the engine is not hot and hard, so crews often strap with ropes in locks. That theatre matters even more in a deep, slow chamber such as Bath Deep Lock.
These films show Bolinder character on other flights (and in the engine room). They are here so you can hear the iron and watch lock technique — not because they were shot at Widcombe.
Have you filmed a Bolinder at Bath Deep Lock?
Public search (as of mid-2026) turns up strong Bath films and strong Bolinder films, but not a widely indexed clip that is clearly both. If you have phone or camera footage of a Bolinder working this flight — especially the deep chamber with audible exhaust — please get in touch via the contact form on Demos so we can credit and embed it.
FAQ
Why is Bath Deep Lock numbered 8/9?
Two original locks were combined into one chamber in the 1976 restoration after a road had been built over the lower chamber while the canal was closed.
Is it the deepest lock in Britain?
It is the second-deepest (~19 ft 5 in / 5.92 m). Tuel Lane Lock (Rochdale Canal) is deeper. Bath Deep is often described as the deepest narrow lock on CRT waters.
Why pumps on this flight?
Each lockage sends water toward the river. Side pounds and electric pumps recycle water so the urban flight can stay open under traffic.
How do Bolinder boats reverse in locks?
Many installations have no conventional gearbox: reverse is by reversing engine rotation, or by rope strapping. Reverse can be hit-and-miss when the engine is cold — see the pair-boating and reverse videos above, and Sound & video.
Is idling a problem for hot-bulb engines here?
Waiting on a busy flight can cool a hot bulb. Technique and heat management matter more than on a modern diesel that is happy to sit and tick over.
Any known incidents on the flight?
In November 2014 a narrowboat sank at Wash House Lock, temporarily closing part of the canal (BBC reporting). Deep chambers reward careful line work and gate discipline.
Visit notes
- Excellent towpath access; popular walking and cycling route.
- Minutes from Bath Spa railway station via the Halfpenny Bridge.
- Film and photograph with courtesy: keep clear of gate beams and working crews.
- This is not a navigation guide. Check Canal & River Trust notices for stoppages and water levels.
Practical notes for Bolinder crews
- Deep Lock takes longer to fill and empty — plan lines before gates close.
- High walls: communication between bow and stern matters; the exhaust note carries.
- Prefer strapping if reverse is unreliable when cold.
- After Top Lock: tunnels and park bridges — low wash, watch for walkers.
Sources for engineering facts include
Grokipedia: Bath Locks
and Canal & River Trust location notes. Research pack:
bolinder-bath-locks-location on GROK_Research.
Related: Sound & video · Not Bolinder · Hot-bulb history · Beverley Beck · Driffield Navigation