How to use locks

Why do we need locks?

When the canals were first built over 200 years ago, they were routed to avoid hills, but where that wasn’t possible, they either dug tunnels or moved boats up and down via locks.  Finding a reliable water supply to ensure that freight could be transported around the country was critical to the success of those early canal companies. 

Nowadays, even though boating on the canals is mainly for recreation, the same challenges still exist. This is because every time a boat passes through a lock, thousands of litres of water are used. Also, water evaporates from the canals during warm and sunny weather, meaning that the Canal & River Trust (CRT) need to regularly top up the water levels to meet these demands otherwise boats would run aground.

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What is a lock?

A lock is simply a chamber with gates at both ends. In each gate are paddles (or sluices) that can be lifted and lowered in order to allow water into and out of the lock. When you drive into an empty lock and fill it with water, your boat will be lifted to the higher level.

When you drive into a full lock and empty it, your boat will be dropped to the lower level. When the water level in the lock matches that on the other side of the closed gate, you can swing the gate open and continue your journey on a new stretch of canal. Once you get to grips with them, locks are all part of the fun of a canal holiday – and a most efficient form of exercise!

It may help you to visualise the lock as a huge bath with the taps (top sluices) at the higher end and the plug hole (bottom sluices) at the lower. This may remind you not to run the ‘taps’ when the ‘plughole’ is open, which would waste water and never allow the lock to fill.

Useful links to help you understand how locks work

A useful picture guide on how to use a lock is demonstrated here by wikihow

A useful YouTube guide on how to use a lock is demonstrated by the CRT here


Going Up

  • Close all gates. Ensure top paddles shut
  • Open Bottom paddles to empty lock
  • Open doors and enter
  • Close doors and bottom paddles
  • Open top paddles to fill lock
  • As the boat rises, ensure that the bow does not snag on the forward gate
  • Open top gates and exit

Going Down

  • Close all gates. Ensure bottom paddles shut
  • Open Top paddles to fill lock
  • Open doors and enter
  • Close doors and top paddles
  • Open bottom paddles to empty lock
  • There is a sill (step) behind you under the top gate. As the boat falls, stay forward in the lock or your boat may strike it as the water level falls; there are sill markers to help you.
  • Open bottom gates and exit