The other version that happens in tight spaces all the time. A boat wakes to terror of slamming the keel on the bottom. They somehow retrieve their anchor and run/flee the the tight harbor at great speed and snag another now taught in shallow water anchor chain with their own keel or rudder. The result the secure at anchor vessels is launched into the side of the boat trying to flee. In most cases the crews of both boats are clueless how boat B slammed into the side of boat A. Bedlam ensues. The point small tight anchorages are fraught with danger and never cross near the bow of any anchored boat. You just do not know where the chain is waiting to capture your moving boat. The first hint may be the other boat rapidly accelerating toward your cockpit.