CRT Safety Alert, Lock Gate Cills

CRT Safety Alert, Lock Gate Cills

01 May 2014

CRT has released the following safety alert after the recent incident at Bath on the Kennet & Avon Canal, where a hire boat was caught on a lock cill and sunk in the lock.

Many hire operators and private boaters are aware of the risks but cill-related sinkings continue to happen. There have been twenty-five such incidents in the past ten years. The latest incident occurred recently when a hired narrowboat sunk in a lock on the Bath Flight. The incident happened when the boat became caught on the cill whilst travelling downhill through the lock chamber.  

When negotiating locks, 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 and the wor ‘cill’ on the copings and a warning sign is placed on the gate. Failure to keep forward of the cill marker can result in the boat being raised out of the water at the stern, which causes the front of the boat to sink. This can happen quickly with the boat sinking or capsizing in seconds.

Hireboat 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.

CRT's Boater’s Handbook carries advice to avoid and recover from lock hang-up incidents:

  • 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.

More information on cill safety can be found at the IWA website.

Photo: Capsized boat that got stuck on cill in Bath flight lock (photo by CRT)

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