¶ Aethervanes
The starting point of just about any spelljamming voyage from the Astral Plane is the local aethervane.
Using an aethervane, a skilled operator can determine the direction and speed of psychic winds, the locations and destinations of color pools, and how long they will stay open, even from a great distance. The contraptions are incredibly complicated and involve no small amount of divination magic. Calibrating, reading, and maintaining an aethervane requires vast amounts of experience and knowledge, as well as patience, a steady hand, and a keen eye.
Aethervanes vary in appearance, but they are generally about the size of a small building and consist of a complex assemblage of brass rods, weathervane-like fins, dials, gauges, and crystal lenses. Aethervanes are much too large and delicate to take on board a spelljammer and thus can only be found on waystations scattered throughout the Astral Plane.
¶ Destinations
In the Aethervane campaign, most spelljamming voyages depart from Bleak Haven, within the Astral Plane. There are three types of destinations travelers typically seek within the Astral Plane:
- a celestial body within a Wildspace system
- a color pool
- a destination within the Astral Plane itself
To reach a Wildspace system or a location within the Astral Plane itself, a spelljammer need only fly in the destination's direction until they reach it. When it comes to traveling to a celestial body in a Wildspace system, however, reaching the system itself is not the end of the journey. A typical system has a radius of hundreds of million miles, meaning that it will generally take a spelljammer traveling at full speed several days to reach any particular point inside the system.
Color pools are portals to other planes that appear and disappear at random throughout the Astral Plane. The majority of them lead to random locations within Wildspace systems, but others lead to the Ethereal Plane or any of the Outer Planes. If a spelljamming crew wishes to reach a destination in a plane other than the Astral or Material, finding a color pool to take them there is just about the only way to do it.
Color pools that lead into Wildspace systems serve more as shortcuts, allowing spelljammers to reach systems that would otherwise be unreachable, and perhaps further reducing travel time if the pool happens to bring them somewhere close to their final destination within that system.
¶ Voyage Length
When calculating the length of a spelljamming voyage, Dungeon Masters should keep in mind that each adventure session ideally takes no more than 23 days (the length of a month in the Bleak Haven calendar). Thus, each leg of the voyage should take no more than 12 days, assuming the characters are also expected to return to Bleak Haven by the same route. Unless the DM has a special reason to set a particular number of days to the adventure, the DM may roll 1d12 to determine how many days a given destination will take to reach. That being said, it is not necessary to specify a length of time at all if the adventure doesn't call for it. The DM can simply say that the characters spend “several days" in transit, for example, and leave it at that.
When spelljamming distances are given in terms of days, it is generally assumed that the spelljammer is traveling at top speed for the entire 24 hours each day. Maintaining spelljamming speed requires that the pilot attuned to the spelljamming helm maintains attunement, contact, and concentration. Thus, the actual travel time may be longer unless the pilot wishes to risk gaining exhaustion or there are multiple pilots on board using the helm in rotation.