My first trip up the mast, excluding using the yard's crane, was a memorable one. I clipped the main halyard to my bosun's chair (a plank of wood with four stout ropes attached to a ring) and had a friend haul me up. I'd seen this done before. I'd seen it done on my boat in fact in exactly the same way. What I didn't account for is that I weigh 210 lbs and the person I'd seen go up before weighed only 150 lbs.
A pendulum effect ensued. Or is that a pandemonium effect?
I could easily have worked on the neighbouring boat's mast as it was periodically and frequently within arm's reach, even though there was a slip between us, but would have only had a second or two before I was rudely swung many degrees to the opposite side. At this point a friend from the yard climbed aboard to take control of the situation. His 250lbs on top of the coach house may have helped...or maybe not. Then the original person who had hauled me up decided he'd better get off so he stepped (jumped really) off the coach house onto the side deck with his 225 lbs. He felt it best to do that at the exact moment we I was accelerating to that side, further adding to my velocity. Another friend, watching from his boat, later stated that this was the moment he went below as he "could not watch anymore".
Finally someone realized that if they lowered me everything would stabilize. And, just as Mr. Newton would have predicted, it did.
Lesson learned: sailing may be an art but science still applies.