Contemplation on the rhythm of a ship

This is not my first time onboard this ship.  I was here two years ago, nearly to the day, spending the holidays in Borneo, Singapore and Mynamar.  I remember spending Christmas Eve standing pirate watch on the dark and windy back deck as we sailed the Strait of Malacca, between Malaysia/Thailand and Indonesia.  Not the best Christmas Eve ever, but different.    Before I get too far off topic, the reason I mention I've been here before is that every ship seems to have a rhythm, a beat to which the crew marches.  It varies a little as the crew composition changes, but remains much the same, belonging to the ship and not those that reside there.  Maybe it has something to do with the layout, I don't know.

So, two years later I find myself back aboard this ship and to my surprise, without much thought, I'm falling back into the rhythm of my last trip on here.  Last night/day?? after my first shift, I hit the galley for a piece of fruit, fired up the sauna, unpacked, took a book and hit the sauna for a good sweat.  Showered, I stopped in the instrument room to check on things, then hit the rack.  This morning, I stopped in the mess, made coffee, toast and grabbed a yogurt and a piece of fruit and then it hit me-this is exactly what I did on here two years ago, every night and morning.  So far this shift, I've worked the same, visited the same places and people on the ship and I wonder how that happens.  Why do I do things a certain way on one ship and totally different on others?  I really don't know unless it's the ship directing the rhythm and rhyme of my daily grind...