Careening is the ancient art of beeching your craft at high tide and then coming back at low tide to scrape the barnacles and other detritus off the bottom of your boat. This sort of crud can have a dramatic effect on the speed and manoeuvrability of your boat or ship.
17th and 18th centaury Pirates had to find remote and secret coves to do this, as they were at their most vulnerable with their ship beached in this manner. It was always a very tense and stressful time. Less so for modern day Cornish fisherman.
