MSC vacation goes like this. Everyone gets two days shore leave per month ONBOARD the ship. 0-3 years federal employment you add 13 days annual leave per year. Over 3-15 years you get 20 days annual leave. Over 15 years is 26 days per year annual leave. That’s the max.
Hypothetically if a new hire works a four month hitch and by some miracle, get relieved on time, he will earn 4.35 days annual leave plus 8 days of shore leave. Leave is only paid Monday through Friday so you are basically looking at about 2.5 weeks off with pay. I was there for 17 years before quitting in disgust.