The International Transport Workers' Federation (ITF) has already found two ships in breach of various ITF and International Labour Organisation rules since it began its "Week of Action" in the Republic on Tuesday.
The ITF's Irish inspector, Mr Tony Ayton, who is on secondment from SIPTU, says there could be many more, but he has decided to resolve difficulties as he finds them rather than simply carry out a survey.
On one of the two ships the owners have now agreed to pay two months arrears of pay, while on the other negotiations are continuing over deductions worth $91,000 (£81,982) which have been made from crew members. ITF inspectors from Belfast, London, Birkenhead and Bilbao are helping Mr Ayton during the week of action, which ends tomorrow.
Last year, Mr Ayton's team found eight vessels in breach of international regulations and industrial action was threatened in four cases before the owners met their obligations. Earlier this year five Pakistani seamen had to wait 18 months in Dublin Port to receive a sixth of the £129,000 owed to them. This was all that was left from the sale price of the vessel after legal fees, stamp duty and other dues were met.
Mr Ayton says some progress is being made, but "every ship we're boarding we find what we expect, sadly - miserable conditions and miserable pay". He puts the main problem down to flags of convenience, which allow shipowners to register in states such as Cambodia and Liberia, which farm out administration and clerical work to private companies.
"These registries have poor safety and training standards, and place no restriction on the nationality of the crew. This results in seafarers not being able to communicate effectively with other crew members as they do not share a common language. With so many accidents occurring at sea each year, lack of communication can determine whether a ship is lost or saved."
The practice became widespread in the 1980s, when major shipping companies in Europe and the US used flags of convenience to cut labour costs and weather the recession. Since then the ITF has been combatting the system by ensuring minimum ILO standards.