This is a Seiko 7A48-7010 “Moonphase” from December 1983. This quartz watch is hacking and the case size is 39.5mm. It has the original bracelet. This is a less often seen variant of the classic two tone Seiko Moonphase. Its design was part of the lead up to age of exploration watches. They made it with a nautical throwback theme. Very cool!