First made out of cork more than 200 years ago, life jackets save lives — but not if people leave them on the dock. Only one in five boaters dons a life vest, despite the fact that people are much more likely to drown while not wearing them. Nearly nine in 10 drowning victims had no life jacket, according to the United States Coast Guard. Part of the problem is that life jacket regulations vary from state to state and country to country. Some research has found that mandates requiring boaters to be jacketed are much more successful at increasing life-jacket use than marketing campaigns encouraging their use.