Note that these rules were designed prior to the release of the 5th edition D&D Spelljammer books. Many of the mechanics below contradict the current “official” mechanics of spelljammers. Rather than revise all of the previous mechanics, they have been preserved below in their original form for the sake of reference. The “official” 5th edition mechanics are described in the Astral Adventurer's Guide. It is up to each DM to decide which version of the spelljamming mechanics to use—the 5th edition ruleset, the legacy Aethervane mechanics, or something else entirely.
Choose one of the ship class options from the table below. This determines the ship’s tonnage range, base speed, turn radius, damage threshold, Strength, Dexterity, and Constitution.
| Ship Class | Tonnage* | Tactical Speed | Spellspeed | Rigging Speed | Turn Radius | Damage Threshold | Str | Dex | Con |
|---|---|---|---|---|---|---|---|---|---|
| Corvette | 1-15 | 100 ft | 50 million mph | 50 ft | 180° | 10 | 16 (+3) | 8 (-1) | 16 (+3) |
| Frigate | 16-30 | 80 ft | 40 million mph | 40 ft | 120° | 15 | 20 (+5) | 6 (-2) | 18 (+4) |
| Cruiser | 31-75 | 60 ft | 30 million mph | 30 ft | 60° | 20 | 24 (+7) | 4 (-3) | 20 (+5) |
| Titan | 76-700 | 40 ft | 20 million mph | 20 ft | 30° | 25 | 28 (+9) | 2 (-4) | 22 (+6) |
* A ship's tonnage is limited by its helm (see below).
Choose a tonnage within the range provided in the table above for the ship's class. Your choice determines the following stats.
Assign length and width to the ship. In addition to the actual size of the ship, this determines the extent of the ship's air envelope. Spelljammers are usually Gargantuan in size, between 20 feet and 300 feet long, and much longer than they are wide.
Typically the square footage of the ship is about equal to tonnage times 125. For example, a 16-ton ship might be 100 feet long by 20 feet wide (2,000 sq ft). That being said, a ship's dimensions and its tonnage are often not directly related.
Choose the material that comprises the ship's hull. This determines the ship's AC and modifies its base speed and ability scores. By default, spelljammers are made of thick wood and have AC 15.
| Hull Material | AC | Tactical Speed | Spellspeed | Rigging Speed | Str | Dex | Con |
|---|---|---|---|---|---|---|---|
| Ceramic | 13 | +20 ft | +10 million mph | +10 ft | -2 | +2 | -2 |
| Thin Wood | 14 | +10 ft | — | — | -1 | +1 | -1 |
| Thick Wood | 15 | — | — | — | — | — | — |
| Plated | 16 | -10 ft | — | — | +1 | -1 | +1 |
| Stone/Crystal | 17 | -20 ft | -10 million mph | -10 ft | +2 | -2 | +2 |
Choose the type of helm that the ship will use. This determines the base cost of the ship, the ship's maximum tonnage, the number of crew needed to pilot the helm, and the areas where the helm can be used, as shown in the table below.
| Helm Type | Base Ship Cost | Max Tons | Crew | Usable Areas | Special Notes |
|---|---|---|---|---|---|
| Artifurnace | 1,000 gp/ton +75,000 gp | 100 | 1 pilot | Material Plane | A legendary magic item must be attached to the helm to activate it. If the item is removed, the helm is destroyed. |
| Chemical Helm | 250 gp/ton | 100 | 1 pilot | Wildspace | Tactical speed and spellspeed are halved (rounded up). |
| Crown of the Stars | 2,000 gp/ton +30,000 gp | 50 | 1 pilot | Material Plane | Pilot must expend 1 level of spell slots per 10 tons (rounded up). Pilot can steer the ship from up to 1 mile away. |
| Crystal Throne | 2,000 gp/ton | 50 | 1 thri-kreen pilot | Astral Plane, Material Plane | |
| Dwarven Forge | 1,000 gp/ton | 700 | 1 dwarf per 3 tons (rounded up; minimum of 100) | Material Plane | Only 1 dwarf must attune to the helm. |
| Furnace Helm | 500 gp/ton | 100 | 1 pilot | Wildspace | A common item is needed to power a Corvette, an uncommon item for a Frigate, a rare item for a Cruiser, and a very rare item for a Titan. If the item is permanent, it powers the ship for 1 month. If the item is consumable, it powers the ship for 1 week. |
| Gnomish Helm | 500 gp/ton | 100 | 1 pilot | Material Plane | Pilot must expend 1 level of spell slots per 10 tons (rounded up). Reduces armament space by 1 ton (because the gnomish helm is a large object). Once per day, the DM may roll a d20. On a result of 1-4, the helm breaks down catastrophically. Before it can be used again, the helm must be repaired by tinker gnomes (or rock gnomes). The repairs take 1-3 hours for a single gnome to complete. Multiple gnomes working together can complete the repairs faster. |
| Lifejammer | 1,000 gp/ton | 100 | 1 pilot, 1 victim | Material Plane | The victim must have 1 hit die per 10 tons (rounded up). |
| Mage Helm | 1,000 gp/ton | 100 | 1 pilot | Material Plane | Pilot must expend 1 level of spell slots per 10 tons (rounded up). |
| Orbus | 1,000 gp/ton | 60 | 1 orbus per 20 tons (rounded up), 1 beholder pilot (usually hive mother) | Material Plane | Hive mother reduces creature capacity by 2 (because it is a huge creature). |
| Pool Helm | 1,000 gp/ton | 200 | 1 elder brain | Astral Plane, Material Plane | Reduces creature capacity by 1 (because elder brain is a large creature). |
| Series Helm | 1,000 gp/ton | 50 | 1 gith or mind flayer pilot per 10 tons (rounded up) | Astral Plane, Material Plane |
Each of the helms above come in two variations: minor or major. By default, a spelljammer is outfitted with a minor helm. At increased cost, a spelljammer can be outfitted with a major helm that increases tactical speed by 20 ft and spellspeed by 10 million mph. The cost for upgrading to a major helm is shown below.
| Ship Class | Corvette | Frigate | Cruiser | Titan |
|---|---|---|---|---|
| Cost | 5,000 gp | 10,000 gp | 20,000 gp | 40,000 gp |
Determine the rarity of the ship based on its cost of its helm. Further modifications (below) may alter the final cost of the ship, but they do not affect the ship's rarity.
| Rarity | Uncommon | Rare | Very Rare | Legendary |
|---|---|---|---|---|
| Base Cost | 1,000 - 15,000 gp | 16,000 - 30,000 gp | 31,000 - 75,000 gp | 76,000+ gp |
Using a ship's rigging requires the attention of 1 crew member for every 5 points of ship tonnage (rounded up). For example, using the rigging on a 23-ton ship requires 5 active crew.
The rigging can be “topped out” (expanded), which increases the rigging speed by 10 ft. Topping out the rigging increases the number of crew required to use it by 50% (rounded up) and increases ship cost as shown below. Rigging can be topped out only once.
Alternatively, the rigging of a ship can be “stripped” (removed entirely). This reduces the rigging speed to 0 ft but also reduces the ship's cost. Ship cost cannot be reduced below 1,000 gp.
| Ship Class | Corvette | Frigate | Cruiser | Titan |
|---|---|---|---|---|
| Topped Out Rigging | 2,000 gp | 5,000 gp | 10,000 gp | 20,000 gp |
| Stripped Rigging | -2,000 gp | -5,000 gp | -10,000 gp | -20,000 gp |
By default, any ship can land on water. Landing gear can be added to a ship hull in order to make landing on solid ground possible. However, this makes it so the ship cannot land on water. In order to be able to land on both ground and water, the ship must be outfitted with special landing gear that is either hydrodynamic or retractable, so that it won’t be destroyed in a water landing.
If a ship is constructed such that no landing is possible, it comes with a reduced cost. Ship cost cannot be reduced below 1,000 gp.
| Ship Class | Water Only | Ground Only | Ground and Water | No Landing |
|---|---|---|---|---|
| Corvette | 0 gp | 2,000 gp | 4,000 gp | -2,000 gp |
| Frigate | 0 gp | 4,000 gp | 8,000 gp | -4,000 gp |
| Cruiser | 0 gp | 6,000 gp | 12,000 gp | -6,000 gp |
| Titan | 0 gp | 8,000 gp | 16,000 gp | -8,000 gp |
Each piece of equipment mounted onto a ship has a ton rating. If the total tonnage of equipment mounted onto a ship exceeds half of the ship’s tonnage, the remainder is subtracted from the ship's cargo space, and the ship is “encumbered”—all of its movement speeds are halved, and any Dexterity saving throws are made with disadvantage.
| Equipment | Tons | Crew | Cost | To Hit Bonus | Range | Damage |
|---|---|---|---|---|---|---|
| Anchor | 2 tons | — | 10 gp per ship ton | — | — | — |
| Ballista | 2 tons | 3 | 2,000 gp | +6 | 150/600 ft | 16 (3d10) piercing |
| Ballista Bolt | 1 ton per 10 shots | — | 25 gp per shot | — | — | — |
| Blunt Ram | 3 tons | — | 3,000 gp | — | — | 88 (16d10) bludgeoning |
| Cannon | 2 tons | 3 | 5,000 gp | +6 | 600/2,400 ft | 44 (8d10) bludgeoning |
| Cannonball | 1 ton per 10 shots | — | 50 gp per shot | — | — | — |
| Grappling Ram | 4 tons | — | 6,000 gp | — | — | 88 (16d10) piercing |
| Jettison | 2 tons | 3 | 2,000 gp | — | 100 ft | 11 (2d10) bludgeoning |
| Jettison Shot | 1 ton per 10 shots | — | 10 gp | — | — | — |
| Lifeboat | 1 per 2 people | — |
1,000 gp per 2 people (x3 if collapsible) |
— | — | — |
| Mangonel | 2 tons | 5 | 3,000 gp | +5 | 200/800 ft | 27 (5d10) bludgeoning |
| Mangonel Stone | 1 ton per 10 shots | — | 20 gp per shot | — | — | — |
| Passage Device | — | — | 10,000 gp | — | — | — |
| Piercing Ram | 3 tons | --- | 3,000 gp | --- | — | 88 (16d10) piercing |
| Planetary Locator | 1 ton | 1 | 2,000 gp | — | — | — |
| Portal Locator | — | — | 5,000 gp | — | — | — |
| Trebuchet | 3 tons | 5 | 4,000 gp | +5 | 300/1,200 ft | 44 (8d10) bludgeoning |
| Trebuchet Stone | 1 ton per 10 shots | — | 30 gp per shot | — | — | — |