Calculating lock transit times, passage time on canals and rivers

On canals your passage time is set by locks, not by knots. Four locks at thirty minutes each make two hours that no distance-based passage plan accounts for, and on top of that there is the waiting time outside the gates, which in high season can be longer than the transit itself.

Locks are where damage happens: a careless approach to the lock wall, a line that parts as the water level drops, a neighbouring boat that scrapes along your topsides. Damage to your own boat goes through the hull cover, damage to the other boat through the liability cover, provided you were at fault.

It comes down to how you handle your lines: never tie them off, always take a turn and lead the end back so you can slip it. If the water is dropping and you cannot free a line that is made fast, you risk a capsize, and then the question of gross negligence comes up. We waive that defence from Basis-Plus upwards.