A former master of the sunken ro-ro El Faro said the boilers were among the most common problems on the TOTE Maritime-controlled steamship and its sister vessels.

Captain Jack Hearn of the Saltchuk subsidiary's TOTE Services arm said a tube in the boiler can "let go" unexpectedly, which requires quick work by engineers to maintain propulsion.

"It's a high-pressure steam, high-temperature system that wears out and needs repair and maintenance quite frequently," he told the US Coast Guard Marine Board of Investigation today.