Spelljamming - Ship Combat

Ship combat is conducted on a 2-dimensional hexagonal grid (hex grid), where each hex is 150 feet, a tenth of the existing SJ rules’ size (500 yards, 1500 feet), and combat is done in 6-second rounds, a tenth of the existing SJ rules.

Where possible the same mechanics are used as in the existing SJ rules, adjusted for the 3rdEd far more skill-based system. The Spot skill of the ship’s lookout must be known, the Hide skill of the ship’s helmsman, the attacking skill of those shooting the ship’s weapons, and the HB of the ship’s helmsman, in addition to the usual need to know the ship’s characteristics, and the SR gained from the helm.

Helmsman Bonus (HB)

The Helmsman Bonus is equivalent to their Helm Pilot skill bonus.

Encounter Distance

The encounter distance – when one ship finds out that another ship is there – is done by means of an opposed roll, Spot vs. Hide.

The Spot roll is +10 plus Ship Size (SS), -1 per 100’, which translates to -3 per two 150’ hexes, and the Hide roll is -1 per SR currently moving. There are no modifiers to Spot for a beam facing, -2 for half-facing, and -4 for stern/bow facing.

By default a ship which is not trying to hide is assumed to have a Hide roll of zero. There may be modifiers to Hide for things like a ship which is the same colour as space (generally black), ships with dulled (+2) or no (+4) reflective parts, or other things ruled by the DM. Being in a dark part of space which is less likely to illuminate a ship will give circumstance modifiers.

The Spot roll used is that of the ship’s lookout, and the Hide roll used is that of the ship’s helmsman.

DMs may wish to avoid having to work this out by placing the ships on the hex grid, and saying that they have just spotted each other, but this removes the possibility of surprise and ambush.

Ship’s Initiative

One initiative roll is made for the entire ship, and this roll is made every round. This roll is modified by the MC:

MC Modifier
 A    +4
 B    +2
 C    +0
 D    -2
 E    -4
 F    -6

Crew status is used as another modifier: Green -2, Average +0, Trained +2, Crack +4.

If the roll is tied between two ship, the ship with the better MC wins. If the roll is still tied, the ship with the more skilled helmsman wins. If tied even then, the ship going faster wins. Ties are avoided as much as possible as who acts first can make a major difference in a battle.

Once the battle reaches the stage of boarding, the standard individual initiative system can be used for these combats – this initiative system is for actions by the ship as a whole.

Ship’s Movement and Armour Class

Movement affects the AC of a ship. The base AC (of 10 – AR – Size Mod + 7) is modified by +2 per SR currently moving.

Maneuvering for best defence and for offense is the responsibility of both the spelljamming helmsman and the rigging crew, oarsmen, or steersman, depending on the type of ship’s hull. All this is measured by the Ship’s Rating (SR) which gives the speed, and the Maneuverability Class (MC) which gives the ability to change direction.

Long Range Combat

This mostly involves ship’s weapons, which work differently in wildspace to how they do when used in an atmosphere and (for example planetary) gravity. Catapults are direct fire weapons, as are all ship’s weapons. However, a minimum range is still used for catapults, which means that they cannot be shot at ships in the same hex.

                     Range     Hull   Personal             Hull  Personal
Weapon             Increment  Damage   Damage   ROF  #Per  Crit  Critical
Light Ballista         6         -      2d6     1/2    1     -      x3
Medium Ballista        4        1d3     3d6     1/3    2    20      x3
Heavy Ballista         2        d4+2    4d6     1/4    4    19+     x3

Light Catapult         5        1d2     3d6     1/5    1    20       -
Medium Catapult        4        d3+1    4d6     1/6    3    19+      -
Heavy Catapult         3        2d4     5d6     1/8    5    18+      -

Bombard                2        1d6     3d6     1/3    3    20       -

Light Jettison         3         -      1d6     1/3    2     -       -
Medium Jettison        2         -      2d6     1/4    3     -       -
Heavy Jettison         1         -      3d6     1/5    4     -       -

Greek Fire Projector   1        1d3     4d6     1/4    3    18+      -

Range Increment: is measured in 150 ft. hexes, and applies in wildspace
Hull Damage: is measured in hull points
ROF: Rate Of Fire, in attacks per full round
#Per: Personel required for full crew
Hull Crit: number needed to roll on ship Critical Hits table

Combat is very similar to the existing SJ rules, except that the attack roll is based on the BAB and modifiers of the person who shoots the weapon, rather than using the weapon’s THAC0. The ship’s AC is used rather than an AR, and there is a -2 range modifier based on each Range Increment. The existing SJ rules maximum weapon range is unchanged, but this is split into ten Range Increments, each giving -2 to hit, as is standard for missile weapons.

Interpretation of Critical Hits

Ships with an active helmsman count as magic items and the helmsman’s saving throw is used. Ships without an active helmsman do not get a saving throw.

The existing SJ rules are used for Fire – against magical attacks – Fireball, for instance – then, with an active helmsman, the helmsman makes a Reflex saving throw for the ship to take half damage.

There is a Reflex saving throw with a DC of 10 plus the Hull Points damage (HP) for all characters hit due to a Critical Hit.

There is a Will saving throw against Spelljamming Shock, with a DC of 10 plus HP. For non-standard Helms this is a Fortitude saving throw with the same DC; the actual helm will not be damaged, just the ability to use it.

Movement and Pilot Skill

It is proposed that in a pursuit situation the two helmsmen make an opposed roll. (d20+HB) The winner gets +1 SR for that round, and if they win by five or more this is +2. Fumbling (rolling a 1) gives -1 SR for this round, a critical (rolling a 20) gives a cummulative +1 for this round, i.e. if you roll a 20 and you win the roll by at least 5 then this gives you +3 SR. Pilots doing this sort of contest tire ten times more quickly than they do in normal piloting.

A helmsman may perform a “full retreat” to withdraw from combat - a DC15 check against d20+HB - but to do so will drain them fully of energy and render the ship immobile until the helmsman has rested. They remain free of pursuit from that particular aggressor for 6d6 hours.


The ramming ship must be fully capable of reaching the other ship, and must travel a minimum of three hexes, to build up speed.

The act of ramming is done as an opposed combat roll. Each rolls d20+Helm SR+HB. Ties go to the defending party.


This can normally only be attempted if the two (or more) ships are in the same hex, and typically they end up side-by-side (unless ramming is involved). If the sum of the ship’s beam length (BL) is greater than 150’ then boarding is possible for ships in adjacent hexes.


Facing is very important for ships, both offensively and defensively. Details of this depend on whether you are using the 2-D hex grid combat, a semi-narrative ‘dogfighting’ system which may allow 3-D combat, or a purely narrative system.

The Armour Class (AC) values given for ships assume that the attacker is positioned so as to face their weapons towards the broadest part of the defending ship. Few ships have the same facing size from all directions, so if you can turn your ship so a narrower part faces the enemy weapons then you are more difficult to hit, and if you can turn your narrowest part to face them then that gives you your maximum AC. If you have multiple attackers who are more agile than you are, in particular if there are at least three, it is very unlikely that you will be able to improve your AC against more than one of them.

When attacking a ship you need to ensure that the ship is in the firing arc of the weapon(s) you wish to use, and preferably they do not have any weapons that they can bring to bear on you. Few ship have weapons that can shoot directly up, or that can bear on you if you attack from below, so in 3-D combat these may be attractive directions to attack from. Another consideration is that you may wish to ensure that you have enough time to turn, so that your atmosphere envelopes and your gravity fields do not come into contact, as this may protect you from some of their attacks.

Modifiers                                        AC
Beam facing (or in 3-D directly above or below)  +0
Half-facing (or in 3-D broadside)                +2
Bow/Stern facing (or in 3-D narrowest facing)    +4


The way maneuvering is handled, if there is not an opposing helmsman, is to assign Difficulty Classes to the various tasks. If the helmsman is not under pressure they will normally ‘take 10’, or even ‘take 20’, but there may be reasons to hurry, and some helmsmen may wish to impress.

Task                                 DC
Activate spelljamming helm           10
Dock ship, e.g. at an asteroid dock  13

Dock with larger ship                15
Dock with equal-sized ship           18
Dock with smaller ship               20

Bring weapon to bear                 15
Bring two different weapons to bear  20

Maneuver in limited space            20
Maneuver in confined space           23
Maneuver in confined, twisty, space  25

Spelljamming - Ship Combat

Mael'Ram HogarthAL HogarthAL