The answer is simple: you need to be able to do the job. If you are able to do the job, then you have the skills to be a deckhand. The more experience you have, the better.
If you have experience, you will have a better chance of getting a job as a deckhand. You will have to prove to the employer that you are capable of doing the job.
If you don’t have experience, you need to make sure you have the skills to do the job. You will have to prove that you can do the job.
If you are a deckhand, you are the one who will be doing the job. You will be responsible for the safety of the crew. You will be responsible for making sure that the job is done.
If you are a deckhand, you will be responsible for the safety of the crew.