I would like very much to run an age-of-sail trade-based campaign. This would likely either be based on a heavily modified version of Spelljammer, or set on an "air world" resembling things like the video game Skies of Arcadia, the board game
Sky Traders, or Jim Butcher's
the Cinder Spires (hurry up on book 2, Jim!) I am also drawing on the game
Return of the Obra Dinn as a glimpse of what "life on a ship" might be like and the sort of personalities you might find.
I am not totally satisfied with the ship combat rules found in Ghosts of Saltmarsh, and will probably be revamping it, not just to get the ship off the water, but also to involve the players more... and make the crew of the ship more important than just a group of nameless NPCs that make the ship go zoom, so long as you throw a charisma check every now and again and pay them in pocket change.
But for starters, I would like to replace the Spelljamming Helm. As written, a mage with a ring of sustenance and a spelljamming helm can forego the need for a ship of any kind, and explore the universe on a chair attached to a couple of planks of wood.
Instead, ships are essentially alive. In the middle of every ship is a crystal heart called a Spelljamming Crystal that provides all the necessary functions of the ship:
- The air envelope. This is now a function of the crystal rather than a natural phenomenon. The crystal constantly refreshes the atmosphere so that tracking the air is no longer necessary. Gas-based spells and effects last as long as they do in a normal environment. The crystal prevents gasses from escaping the envelope.
- Gravity. The gravity plane is decided when the ship was designed and the crystal installed. It cannot be "shut off" or altered.
- Levitation. The crystal allows the ship to levitate upwards at a slow rate. This ability is typically only used for takeoffs and landings.
- Harnessing the Starwind. Beyond the edge of a planet's atmosphere, there is no real wind or water to sail in. Instead, Spelljamming ships depend on harnessing the Starwind, an intangible force that normally passes through physical objects, but can be harnessed by allowing the ship's sails to interact with this wind.
- Orientation. The crystal gives the helmsman a degree of control over the ship's roll, pitch and yaw so that the ship can be steered. Combined with the sails, this gives the ship a similar ability to steer as their oceanic counterparts.
- The Web. The web is a shell of force that surrounds the ship while on voyage for protection. It is normally invisible, only appearing briefly as a network of glowing fibers when an object or spell is repulsed by it, and when it is raised and lowered. It is located in the same place as the air envelope. The Web is permeable one-way: objects and spells from inside the web can travel out of it, but objects and spells from outside cannot travel inside. This includes spells such as Teleport, Divinations, etc. It can interfere with the function of some magic items, such as sending stones, which can only send messages while within a Web, but not receive them. The Starwind and the Phlogiston are the only known substances capable of penetrating the Web. Attempts to bypass the web by transmuting oneself or other objects into Starwind or Phlogiston have so far proven fruitless, as the Web is somehow able to filter it out. The Web can be damaged, however, and has a hit point total. When the Web is at 0 Hit points, the Web is dropped, and the ship loses the ability to harness Starwind, Levitate, or change orientation. It retains the ability to maintain the air envelope and gravity, and is effectively immobilized without another means or propulsion. While under the effects of a planet or other gravity-producing body, the ship will likely crash, but while in Wildspace or the Phlogistion, the ship will rapidly slow until it comes to a stop.
- Webcasting. As a crew becomes familiar with a ship, so too does the ship become familiar with the crew. This symbiotic relationship between ship and crew can have a number of surprising effects. While the Web is raised, officers aboard a Spelljammer can offer the ship Spell Slots allowing the ship to cast spells during combat. As a crystal grows in strength it can learn spells from it's crew- what kinds depend on the sort of crewmembers serve the ship. A ship with a Wizard captain and a Cleric 1st mate aboard may learn to cast Acid Cannonball or Repair Web. The ship may even learn non-magical maneuvers from particularly skilled crewmates, like the ability to rage like a barbarian or act with cunning like a rogue.