Time and time again I try to think of a good way to implement the feeling of the Golden Age of Piracy into the space travel setting. But no matter what I try to come up with, it all fails to adress one pertinent issue: the lack of air.
I don’t mean as the lack of air that would allow for an open deck and ship boarding. Breathing is not the issue in here, air resistence, or rather, the lack of it, is.
If the Dark Wind function like solar wind, it will just serve as a source of energy. The ship would still need its propulsion system. And the flow of such Wind would be irrelevant, as long as the ship keeps itself in the area with the most concentration.
However, if the Dark Wind acts more like the wind down on the planet surface, and it actually pushes the ship by means of its sails, then the speed would constantly increase, as there’s no air to slow it down until a balance is formed between the wind strength and (in the case of sea ships) the air and water resistence.
This in turn would force a space ship to use its bow engines in order to slow it down. Also, what happens when different currents join? Do the ship needs to leave the stream and reposition itself, as to avoid an area of confluence that could damage the sails?
Assuming that Dark Wind behaves like solar wind, the ship would still need its propulsion and move alongside the Dark Wind streams.
I believe this might be the best, if not only, workable solution. But also, because of the lack of air resistence, the ship needs to have its engine working only for so long, just to adquire the required speed.
We could have them easily overheat, or have the sails, that collect the energy needed to power them, to be so fragile and/or consumed by the Dark Wind, that its use is minimal. Still allowing for absurd speed in space, but not as an infinite source.
Adding the piracy aspect, vessels not equipped for long travels, that could sense the heat signature of passing ships, constantly patrolling areas next to confluences, with heavy traffic.
This brings up the submarine aspect, a game of cat and mouse, where the travelling ship would be monitoring the trajectory of anything near it, if something was to have some paralel route to itself, then it probably meant it is someone, checking on them.
Because there’s no major heat signarute with the engines off and sails recovered, the pirates would not know for sure, without closer inspection. And though raising sails and blasting the engines would give the ship enough speed to outrun the attackers, there’s that window where the ship would be very visible but incredibly vulnerable.