A lot of interviewers will ask you to describe what you feel your greatest strength is. Don’t be afraid to sell yourself when it comes to a question like that. You are there to show them that you are a valuable and skilled mariner so give them an identifiable strength that you can prove to them later on if they hire you.
The next question they might ask you is “What is your greatest weakness?”. That’s one question to prepare for ahead of time. Best thing to do there is be honest with them - but not brutally honest. “I’m a raving alcoholic!” is not the answer they are looking for. “Well, I wish I had more experience with <INSERT RELEVANT BUT NOT LIFE-CRITICAL MARITIME SKILL HERE>, and I’m hoping that a job like this will give me a chance to expand my horizons.” might be a better answer.
Something to think about. Hope that helps.