Proximity+DR=Plunder-able.
I, and a couple others I spoke to, believe that having to be docked in order to fight has a huge negative impact on the realism of this game. It also creates the need for DR to be the only deciding factor to determine who can be plundered. I suggested this elsewhere and didn't get a response so here I go again.
The map could be made up of grid coordinates just like it is in reality. Distance could be the main deciding factor for whether a player can be targeted. If the potential target fleet has on 1 Danger point, the distance would have to be shorter and at 2 Danger it could be longer. For 3 danger, distance is unrealistic but not nearly so much as it is right now. We don't generally have battles for the benefit of the spectators in the ports so the plunder button should be located in the screen of a specific fleet and that fleet would be the one used to plunder. There's no need to eliminate the existing DR=Plunder-able method when it comes to port battles and the Port Battles report could still include attacks made in the area of that port. It is still extremely far fetched that my fleet conducting its unload/load in Tzogos should be targeted by a fleet in Tortuga just because it will eventually get there. Maybe if it were on the 25% of the route that is closest to the port of the attacking fleet, it could be targeted provided the situation still exists by the time the attacker chooses his target and attack fleets. A fleet pausing its trade route to compensate for speed would increase the length of its vulnerability time in the port it takes its break while reducing the amount of time they are in danger at a different port along their route. This could be further exaggerated by using max crew to move into and out of a port as fast as possible which would require an even longer pause wherever it is taken.