You must pass a certain period of time before you can qualify for the exam. Generally, it takes three months to train. Generally speaking, the training time of seafarers' four certificates is between 15-20 days, while seafarers and mechanics need to be trained for about 3 months, which means that it takes about 4 months for sailors to get internship certificates. After sailors and mechanics get the internship white certificate, according to the regulations of the National Maritime Safety Administration, interns have to practice for six months before they can get the real sailor and mechanic competency certificate.