Two engineers were found guilty in a federal court on charges of falsifying records to hide improper bilge waste disposal from a chemical tanker.
The jury in Charleston, South Carolina, convicted Herbert Julian of violating the Act to Prevent Pollution from Ships (APPS) and of obstructing justice.
And it found Panagiotis Koutoukakis guilty of a felony relating to APPS and of falsifying records.
The men, successive chief engineers on the 2014-built Green Sky, are alleged to have regularly ordered the illegal pumping of oily wastes into the sea, using a so-called “magic pipe” to bypass the oil water separator.
They then covered up the crime by falsifying the ships oil record book.
US Coast Guard (USCG) began investigating the vessel in August 2015 when it was docked at the Port of Charleston’s container terminal in North Charleston.
Koutoukakis faces a potential 25-year sentence while Julian’s maximum punishment is five years.
The Green Sky’s captain, Genaro Anciano, has previously pleaded guilty in Charleston to one felony count of obstructing a USCG investigation.
And the ship’s operator, Greece-based Aegean Shipping Management, had previously pleaded guilty to similar charges. Both those guilty pleas were withheld from the jury in the latest case.