The 7,000-ton freighter Pioneer Atlantic docked at the Aughinish Alumina facility in Foynes earlier this week and had been due to leave at daybreak yesterday.
However, the International Transport Workers Federation, in association with Siptu, boarded the vessel on Tuesday night to ensure crew concerns about the safety of the vessel were addressed before it left.
The alleged onboard defects included leakages and difficulties with the engine and the cargo hold.
Two crewmen have since left the vessel to be repatriated to the Philippines, and a further three are due to leave before the end of the week. They include the first officer, chief engineer, and assistant chief engineer.
The ITF union body said it reported concerns about the vessel to Port State Control on Sunday but, as of last night, its officials had not inspected the ship.
The ITF said that, under the Maritime Convention 2006, where there is prima facie evidence of safety concerns, Port State Control must carry out an investigation to satisfy itself that it is fit to sail.
Siptu industrial organiser Tony Carroll, who was onboard yesterday, said: “The fact that the three most senior officers on board after the captain are not happy to sail with this ship in its present condition is testimony enough to the state it is in.”
Last night, the Department of Transport issued a statement in which it said: “The Marine Survey Office has a surveyor travelling to Shannon/Foynes port tomorrow, to carry out further enquiries on board. If we detect any Port State Control related issues, then we will carry out an inspection, but we may find this is solely an employment-related incident, falling outside the scope of Port State Control. The vessel has a good inspection record with the last two inspections in Germany having zero deficiencies.”