Bottom paddles left slightly open, boat grounded on cill etc. You would think anyone noticing that there was a problem caused by lack of water would think to add water from the other end, but modern urban people have no concept of practicality or staying calm in a crisis. They think any problem can be solved by screaming louder. Never mind, come the apocalypse they will make great fodder for the zombies.
Tel - LEM - a - Khus for the thickos that didn't do the classics at proper school.
I caught a snippet on FB about a NB that sunk on the K & A and had to be raised using the " community pump" plus a borrowed one. The boat had no bulkhead between the engine bay and the accommodation and it was overwhelmed by rain. The owner slept through it all and only woke when she felt a bit damp. She was gutted because had she been awake she said she could have turned on the bilge pump. Obviously never heard of a float switch. There is now a crowd funding page set up for her Phil
The foundations for incidents such as this, and the numerous occurrences of low pounds that have lost their water through paddles left partially open, are firmly rooted in the winding down paddles and routine unnecessary closing of gates culture that's become a major feature of today's canal pleasure boating, and has bred generations of pleasure boaters who are oblivious to the need to make visual checks for significant leakage whilst operating locks.
Paddles that are dropped, as opposed to being wound down, very rarely stop short of being fully closed, and adding to the likelihood of problems arising from only partially closed paddles is the mindless practice of routinely closing gates behind a boat exiting a lock, whether necessary or not due to leakage at the other end of the lock. The practice in itself, at least for those with enough wit to understand that it was originally introduced as a water saving measure rather than to make life easier for a following boat, leads to a complacent frame of mind which will never prompt any of today's breed of pleasure boaters to relearn the now long forgotten working boat practice of visually checking that the gates they've just closed as part of the process of operating a lock aren't leaking.
Excessive quantities of water leaking into or out of a lock that's being filled or drawn off, with or without a boat in it, are not difficult to spot, . . be it through partially open paddles, from fouled or worn cills and gates, or through or between the gates themselves. Water squirting out from between the the lower parts of mitre posts or the heel posts and the hollow quoin might look spectacular, but the serious leaks that account for the loss of significant amounts of water, including paddles that aren't properly closed, show up as a turbulent looking 'boil' which wells up close to the bottom gates. Leaking ground paddles create a similar looking effect at the top end of the lock chamber after the water level has fallen well below the cill.