So, after reading many forum posts it seems as though some people feel as though there is no incentive to push for rank (aside from eternal glory). Here is an idea that will help give incentive for players to attain and maintain a high rank. Explored Island's could yield plunder based on the captain's Pirate Rank. So, when navigating to the map and collecting the gold/grog from the uncovered islands, a player with a higher pirate rank could collect a higher yield based upon his or her pirate rank.
Thanks for the +1's . If you guys have any other ideas or recommendations for offering incentives to maintain a high rank please share!