Expanded Spelljamming

The existing Spelljamming rules for 5e are fairly simple and don't really have the complexity that we will need for this campaign. What follows will be some house rules that we will use to expand on the Spelljamming rules. I've looked at a lot of the available expansions that are out there, and may have picked up an idea here or there, but what follows is specific to our campaign.

First, review How Spelljamming Works.

Then, we riff......

Spelljammer Crews

The crew of a spelljammer ship, as presented in the rules above, is primarily set at 2+the number of crew required to fire weapons. This makes sense, since, as presented, the ship is controled and propelled by the power of the Spelljammer Helm, and the crew sized for weapons can be expected to handle repairs and other duties when they're not operating the weapons. This is far less than a comparable sailing ship, which would need to have enough crew to handle the sails and fight at least half of the guns -- and probably marines to repell boarders. All of that will require a lot of officers to manage, too.

Spelljammers get away with a lot less, at least in Astral space, and typically need to because of the problem of breathable air -- lots of crew (or passengers, for that matter) means lots of breathing.

So, most spelljammers limit themselves to as few bodies as possible.

So what are the Sails for?

I've seen a lot of different ideas out there on the webs. The truest answer, in my opinion, is "They look cool." But that's not much of an answer. If we imagine that the sails are necessary to propel the ship, that could be cool, but it would add the need for a lot more crew, and it would be trying to make the ship fit the sailing ship model rather than working with the idea of the Astral sea. So I don't like that idea.

So, here's the trick. The sails are a manifestation of the power of the Starjammer Helm. The helm is focusing the imagination of the jammer and using it to propel the ship -- and in the case of the humans, elves, and dwarves, that's typically imagining sails. Others might imagine other modes of propulsion, and that would be what manifests.

What is NOT a figment of the Spelljamming process, and is physically there, are the masts. These serve the purpose of expanding the air envelope of the ship, which means there's more breathable air and the ship can travel further without renewing it's air supply. That explains why so many other ships (like the Nightspider) have long legs or other design elements that extend out beyond the necessary body of the ship -- they create larger air envelopes.

Spelljammer Combat

This is the important stuff, right?

Speed, maneuvering and Pushing it

Spelljammer ship speed, when it's close to another object, is the ships "flying" speed, set for each ship design. The rules also say that the ship is about as maneuverable as a sailing ship of the same size. That's painfully in-exact, and doesn't reflect the dramatic difference in resistance for a ship in the water vs. a ship floating in space.

Because of the size of most ships, most won't move a full ship's length in a given six-second round. For example, the flying fish ship is 120 feet long and has a base speed of 40 -- so it will move a length in three turns. This is an important thing to understand -- these ships move slowly, not zipping around like fighter jets.

Mapping Spelljammer combat and Maneuvering

Spelljammer combat is played out on a hex grid, where each hex represents 20 feet. Most ships will be multiple hexes. The scale needs to be small to represent the pace of movement, but that's going to mean a ship like the Yamato will be represented by a massive token at this scale -- it's 50 hexes long! So, in most non-abstract scenes, the Yamato will be represented by the side of a map.

Facing

The spelljammer rules state that in a given round a ship can fire all of it's weapons at a target, basically moving around to explose all of it's weapons to fire on the target. In a six-second round, that represents too much mobility, so we will replace that with some simple judgement. Most existing Spelljammer designs have weapons mounted to face forward or to their rear, so if the ship is moving towards it's target, it's forward mounted weapons can fire on it, and if it is moving away from it's target, the rear mounted weapons can fire on it. If it's not clear, then the pilot of the spelljammer can choose one, but in a given round it's not possible for all facings to fire on a single target.

The Yamato, and other suitably large ships, will have their own variation on this based on their design. For example, the Yamato is designed to deliver most of it's attacks to one side or the other, and many of it's weapons can't fire directly in front or to the stern.

Turning

A ship can turn and face in a new direction in the time it takes it to move a full length. In water, or other conditions that create strong resistance to turning, that change in direction can only be 60 degrees. But in air or space, it can be any direction up to 180 degrees.

That means that it will typically take more than an action to make a turn. The following rules apply to turning:

• To complete a turn, the spelljammer must concentrate on the turn. Should the jammer lose concentration, the ships stays on it's current heading and the turn needs to be started again.
• The number of actions it takes to complete a turn can be reduced if the spelljammer burns a spell slot. The turning time is reduced by Jamming (see below).
• It is not necessary to move forward (or backward) to complete a turn -- a Spelljammer ship can turn in place, but it takes as many actions to complete the turn in place as it does if the ship is moving.
• A spelljammer can only spend one action on turning a ship per turn.

Jamming

• Reduce the number of actions required to complete a turn by 1 (minimum 1)
• Increase the ship's speed for the round by 10 feet
• Evade enemy attacks and increase the ship's AC by 1 until the start of the Jammer's next turn.