D'karr
Adventurer
I think that these kind of "professions" would be best handled as character backgrounds and feats.
If there was a character background that involved sailing this background would allow +2 to any checks that involved sailing. For example, if the character needs to climb a rigging he gets a +2 to his athletics roll. He needs to determine if a storm is coming, he gets a +2 to his Nature roll. He needs to swing from ship to ship on a rope, +2 to acrobatics, etc.
If a player wants to add this at a later time than at character creation he takes the feat "Sea Legs" or whatever, and that feat provides some of the same benefits but maybe at a lower rate. But are limited to things that are used on ship.
If there was a character background that involved sailing this background would allow +2 to any checks that involved sailing. For example, if the character needs to climb a rigging he gets a +2 to his athletics roll. He needs to determine if a storm is coming, he gets a +2 to his Nature roll. He needs to swing from ship to ship on a rope, +2 to acrobatics, etc.
If a player wants to add this at a later time than at character creation he takes the feat "Sea Legs" or whatever, and that feat provides some of the same benefits but maybe at a lower rate. But are limited to things that are used on ship.