The US government has tapped Crowley Maritime to lead efforts to boost its military sealift capacity with secondhand ships in a $638m deal.

The Jacksonville-based company announced it had been awarded the multi-year vessel acquisition management contract by the US Department of Transportation's Maritime Administration (MarAd) on Wednesday.

In the agreement, Crowley will work to acquire vessels using proprietary technology for the country's Ready Reserve Force, then re-flag, re-classify or modify the vessels as needed and maintain and operate them moving forward.