Investigators are looking into how an OSV undergoing sea trials saw three injured and one die. The Astro Tamoio was performing sea trials in Guanabara Bay near Rio de Janeiro over the weekend when a water cannon went off, aimed at the deck rather than out to sea.
A 23-year-old female crewmember died and another three colleagues were hospitalised. The ship is now anchored while investigators work out how the accident happened.
Normally, any water cannon tests in Brazil have to be carried out in the presence of navy personnel.
The ship is owned Astromaritima Navegacao and is due to launch on October 1.