Career change at 39

First off thanks for reading this post. I am a 39year old male nurse. I am very interested in becoming a merchant marine. Honestly, I don’t know where to to begin after I get my TWIC, MMC, and the STCW95. I live in the Midwest, im willing to go anywhere, and relocate. Im fairly healthy. But is 39 too old? Nursing is safe, but I am not really better off now than I was 10 years ago.