There was a mod for Warlords called Pirates! which can be found at:

http://forums.civfanatics.com/showthread.php?t=198849&highlight=Pirates%21

This mod contains a large number of naval promotions such as Cotton Sails, Copper Plating, Chronometer and Grapeshot. It may be worth taking a look at this mod to see if there are any naval promotions that are worth considering for use in AoD II.

Like the sound of it, also think the promotions used would fit as changeable ship professions (I believe Dale has enabled that now in the XML schema)

Got an old never-realized concept in my sig still...Just some loose ideas, feel free to grab'n'mod whatever.