Sailing
Sailing is a mix of specific knowledge, honed skills and a gut instinct for the wind and the feel of a ship or waterborne vessel.
0: "Argh"
1: You could tie off a boat.
2: You've served as a cabin boy or girl.
3: You've earned the right to be called sailor, corsair, or pirate.
4: You know real pirates don't say "argh".
5: Your sail strikes fear on the high seas.
6: You could sail a skiff through a monsoon while hunting down the one eyed white whale.