How many do you need to open a sea lock gate?

Here in Bude almost 20 volunteers were needed to operate the Bude canal gate to allow a sailing yacht depart for Padstow. What was even more surprising was to learn that the operation of the lock gates only happens 3 or 4 times a year?! Hence a crowd of visitors had assembled to view this event. We stumbled upon it on our walk. Earlier we met two of our oldest friends, from our student days, for lunch in Wadebridge.