A new report recognising the challenges facing the US-flag deep sea fleet recommends the Department of Transportation (DOT) "expeditionally finalise" national strategies that will boost its ability to compete internationally.

The US Government Accountability Office (GAO) report lists economic viability and the availability of qualified American mariners as the biggest setbacks to the sustainability of the US-fleet.

The directive to develop national strategies was mandated by the US Congress back in 2014, but has not yet led to fruition.