Petty Officer 2nd Class Davis Alexander, a boatswain’s mate aboard the Coast Guard Cutter Elderberry, uses calipers to check the thickness of a chain link on the Coast Guard Station Juneau, Alaska, pier March 31, 2015. Constant chafing can cause the chains to wear down, eventually leading to a break and a lost buoy. (U.S. Coast Guard photo by Petty Officer 2nd Class Grant DeVuyst)