A US researcher believes it is time it open up the Jones Act market to foreign-built ships to save an ever-dwindling fleet that is too costly to replace.

Jonathan Helton, a research associate at the non-profit policy think-tank Grassroot Institute of Hawaii, tallies the oceangoing commercial Jones Act fleet at only 92 ships, down from 257 in 1980.

The 1920 federal law requires all cargo transported between US ports to be carried on vessels that are US-flagged and built, and mostly owned and crewed by Americans.