You can go abroad with a service book, such as being a chef. But if you are a mechanic, you need a certificate of competency as an organic worker.

Of course there are exceptions. For example, two mechanics are enough for the minimum personnel on board, but in actual work, three mechanics are needed to meet the work needs, so you can work as a mechanic, and the other two mechanics must have the qualification certificate of organic workers. Of course, your salary may be lower than that of the other two people with certificates of competency as organic workers.

From your question, I feel that you are very young. If you are interested in sailing, you can consider taking the Mifune Certificate, which is not difficult for young people. Class c is fine, and domestic routes can run seagoing ships. Of course, you have to take the mechanic's license first. Machinist qualification certificate/kloc-can be admitted after 0/8 months (the time of this qualification certificate may not be very accurate, but it has been changed, so you can consult relevant departments, such as maritime safety administration).

Good luck in your career!