As an "occasional" boater, I'm always interested to learn from those who have more experience so this thread is particularly interesting to me.
A recent cruise along the GU between Warwick and Napton in a 62-footer demonstrated, however, that it didn't matter which of the paddles was raised as the water seemed to enter the lock from the left side no matter what. I was glad of a rope around a bollard as the bow began to swing towards the opposite side of the lock. It certainly stabilised the boat and prevented any violent movement or collision with the infrastructure.
I've read the advice about keeping the boat towards the back of the lock, too, with interest. Yes, I can see the logic with a shorter craft, but am always mindful of the health of rudder and prop so tend to keep a distance between the boat and gates.
We were happy to pass on the wisdom to the "whack up the paddles brigade", with whom we shared one or two locks, that it's a lot safer and smoother to do things with less haste, preventing a dramatic "kiss" between narrowboats. I am relieved that we didn't share with GRP/ wooden boats!
Back to the Oxford singles next time for us!
gardencoaster