RedactedNarrative: Unit 1 was traveling down river with the tide in the vicinity of the railroad trestle on the Ashley River.  The trestle was out of service for repairs so the operator attempted to go under the bridge.  As he was approaching the bridge, the current caught the stern of his vessel, rotating it and pinning the vessel against the bridge.  The operator attempted to reverse engine and pull against the tide at which time the vessel capsized and threw the operator and passenger into the water.  They were picked up by a passing vessel and taken to land.