Twenty five canal boats have been sunk in locks in the last ten years because they sat on lock cills, according to The Canal and River Trust. After another recent cill related sinking on the Kennet and Avon Canal C&RT is reminding boat owners and canal hire firms that boats should keep clear of the lock cills which lie below the water close to the top gates of most canal locks.
This latest occurrence was when a hired narrowboat sank negotiating a lock. The incident happened when travelling downhill through the lock chamber. It is essential that proper control is maintained over the boat and that it is kept forward of the top lock gate cill. The extent of the cill is marked by white lines on the copings with the word ‘cill’ stencilled on and a warning sign is placed on the gate. Failure to keep forward of the cill marker can result in the boat sinking at the front and raised out of the water at the stern. This can happen quickly and can result in the boat to sinking or capsizing in seconds.
C&RT emphasise that Hire Handovers should emphasis the proper navigation through locks and the potential risks if the boat is not properly controlled. Private boaters should ensure they remain vigilant to the risk of cills and becoming hung up as the lock empties.
Not all lock sinkings are caused by downhill boats sitting on lock cills though, another common cause is when a boat bows get stuck under projections on the top gates when going uphill. And boats have also been sunk by boaters opening gate paddles too early and swamping the foredeck. A single narrowboat in double locks can be difficult to handle if paddles are opened too quickly.
The C&RT Boater’s Handbook (click for pdf download) carries advice about how to avoid and recover from lock hang-up incidents. Advice includes;
- Floating freely? As the water level rises or falls, keep a continual check on your boat.
- Is your rudder caught on the cill? (Going downstream) Close the bottom gate paddles to stop the water falling further. Slowly open the top gate paddles to refill the lock. Check for damage.
- Is the side of your boat caught against the lock wall? (Going either upstream or downstream) Refill the lock and check for damage.
- Is the front of your boat caught on the top gate? (Going upstream) Close the top gate paddles to stop the lock filling. Open the bottom gate paddles to allow the water level to fall.
- If you’re sharing the lock with another boat, is there a safe distance between you? (Going either upstream or downstream) Use ropes looped round the bollards to keep you in position.
- Are your ropes snarled or too tight to let your boat move down freely? (Going downstream) Slacken them off if you can. If not, refill the lock
Working boatmen would always keep narrowboats against the bottom lock gates when going downhill to avoid grounding on the cills. Going uphill they kept against the top lock gates. Leisure boaters often prefer to hold their boat in the centre of the lock, either with ropes or engine.
Thanks to C&RT for permission to reproduce some of this report and for images.