Curves, chains and a crescent moon

I shared the canoe pool with a young photographer. He had two friends with him who amused themselves by doing catherine wheels and other such stuff. The sort of things you do when you seem to be spending an enormous amount of time doing nothing much. After about 1/2 an hour I heard him say to them - "just one more". There were three more after that and then he walked down to the beach in front here and there were a few more. They were very understanding friends I thought.