Can I still use it to settle in Hong Kong after obtaining a third-class seaman's certificate?

Look at the time According to the Rules for the Certification of Crew Examination in People's Republic of China (PRC) and the Rules for the Certification of Crew Examination in People's Republic of China (PRC), those whose certificates of competency have expired for 5 years or more 10 years or less should participate in simulator training and knowledge updating training, and pass the theoretical examination and project evaluation of corresponding random subjects. Whether it is feasible to obtain three seafarers' certificates to settle in Hong Kong depends on time.