Near sunset on the evening of May 4, 2013, the harbor assist tug Kaleen McAllister got underway from its berth in Baltimore Harbor with a crew of three to assist in docking a tow and barge entering the port. A few minutes later, the tug struck the charted edge of an adjacent collapsed pier and began flooding. The tug returned to its berth, where the crew and shoreside support personnel attempted to control the flooding, but the effort was unsuccessful and the vessel sank alongside the pier within 30 minutes. No one was injured; the sinking resulted in the discharge of about 2,400 gallons of diesel fuel and estimated vessel repair costs of $1.5 million.

​​​The e probable cause of the grounding and sinking of the harbor assist tug Kaleen McAllister was the mate’s practice of transiting near a submerged portion of a collapsed pier, a known and charted underwater hazard, which ultimately resulted in the vessel striking the obstruction.​