Ocean Routes (Wind and Curents)

With this idea, I ideally envision a map script laying down visible "routes" (new graphic which also indicate direction) on ocean and coastal water plots.

Ships traveling on these 'routes' gain a movement speed, so long as the do so in the direction of travel the route is pointed.

These routes cant be upgraded or altered, as the represent prevailing winds and current which allow a natural increase in ship movement speed.

If possible, they could be made "invisible" until certain techs reveal them, and other tech increase the gain rate of their use.

How achievable is this? Especially in gaining the speed bonus if only traveling in the proper direction.