Maneuverability!: Spelljammer 5e Conversion

Welcome to what will hopefully be the last Spelljammer 5e conversion post covering movement. I covered long-range movement and Spelljammer Rating in the last few posts so the only thing left is tactical movement. Tactical movement will come into play if you plan to use ship-to-ship combat in your Spelljammer game. The rules for tactical movement in the original campaign setting boxed set were modified from existing aerial combat rules for the edition, but I couldn’t find any 5e rules for aerial combat. I think I came up with rules that are fairly straightforward, but I need to see how these rules run in a game scenario to know for sure.

I am going to make a lot of references to hexes in this post. In the original Spelljammer rules a hex in space was 500 yards (457 m) and I’m going to carry that over to 5e. That distance may seem like a lot, but most ship based weapons in the game have ranges of well over 1,000 yards (914.4 m).

Tactical combat for Spelljammer was broken up into three sections in the guidebook; facing, movement and speed. Facing is what direction the ship is pointed in relation to the six points of a hex. Different ships were able to change facing a certain number of times based on their maneuverability. That’s pretty simple. It was the combination of movement and facing where things got more complex. In 2nd Edition AD&D there was a rule involving Maneuverability Classes for aerial combat. This rule originally covered flying creatures such as dragons. Here’s the excerpt from the 2nd Edition AD&D Monstrous Manual:

Flying creatures also have a Maneuverability Class from A to E. Class A creatures have virtually total command over their movements in the air; they can hover, face any direction in a given round, and attack each round. Class B creatures are very maneuverable; they can hover, turn 180 degrees in a round, and attack in each round. Class C creatures are somewhat agile in the air; they cannot move less than half their movement rate without falling, they can turn up to 90 degrees in a round, and attack aerially once every two rounds. Class D creatures are somewhat slow; they cannot move less than half their movement rate without falling, can turn only 60 degrees in a round, and can make a pass once every three rounds. Class E includes large, clumsy fliers; these cannot move less than half their movement rate without falling, can turn only 30 degrees in a round, and they can make one pass every six rounds. See Chapter 9 of the DMG for more information.

Maneuverability Classes were carried over for Spelljammer with a sixth class of F being added for ships that were converted sea vessels.  This system seems fine at first glance, but I found it lacking in some key areas. First off, even though the game takes place in space these aren’t star-fighters that we are dealing with. They are built using a fantasy level of technology and are often just converted sailing vessels. As such they shouldn’t be too maneuverable. The Maneuverability Class of A goes right out the window for me because of this. I also felt like maneuverability needed a spatial dimension as well. When a real ship, or even an airplane, turns they don’t do it while standing still. They complete the turn along a specific distance. Maneuverability needs to reflect this.

For this conversion I have decided to use five Maneuverability Ratings (MR). Strangely enough, even though Spelljammer offered six classes there were no ships listed in the rules with a Maneuverability Class of A. Unlike SR a lower MR is better. The MR of a Spelljammer ship will tell you three things that you need to know in combat. The first is how many hexes the ship travels through to make a 90 degree turn. The second is how many hexes it takes for the ship to accelerate from a stop to maximum SR. Finally, MR will tell you how many hexes it takes a ship to decelerate to a stop. The MR of a Spelljammer ship is in no way impacted by the helm or its operator, but speed will still play a factor.

90 Degree Turns

MR1
MR1

This illustration shows a 90 degree change of direction for an MR of 1. The ship starts in one hex and moves one hex before it has made a complete right turn.

MR2
MR2

An MR of 2 moves the ship through two hexes, one forward and one right to make a right hand turn.

MR3
MR3

A vessel with an MR of 3 must move through three hexes before it has turned 90 degrees.

MR4
MR4
MR5
MR5

You can see the same behavior with ships of MR 4 and MR 5 moving through four and five hexes respectively.

These turns do not just left or right hand turns along a horizontal plane. Space is a three dimensional battleground so Spelljammer ships may also make direction changes from the horizontal to the vertical plane.

Acceleration and Deceleration

Maneuverability Rating in regards to acceleration and deceleration of a ship works in much the same way as it does for turning. A ship with an MR of 1 would need to move one hex before it reached speed and one hex before it came to a stop. An MR of 2 would require two hexes to speed up and two to stop, etc.

Maneuverability and Speed

I said that SR had no impact on MR, but it does factor in when running ship-to-ship combat. A Spelljammer ship with an MR of 5 has to move 2500 yards (2286 m) before it completes a 90 degree turn. This doesn’t seem like much until you consider speed into the equation. A ship with an SR of 1 would take fifty rounds to make that turn where a ship with an SR of 10 could make it in just five rounds.

Ascending, Descending and Reversing

I know the question is going to come up in my game of how quickly a ship can move straight up or down and how fast it can go in reverse. My first instinct for this rule was to assign an arbitrary SR of 1 to these maneuvers, but that seems too limiting in combat. I’m going to start my campaign with the rule that spelljammer ships can move straight up or down and move in reverse at half of their max SR (round up) as long as they begin the maneuver from a dead stop. I’ll see if this holds up in actual game play and adjust it as necessary.

Maneuverability Rating
Travel among the stars is fraught with dangers. Among these dangers is the very real possibility of encountering hostile ships. When engaging in ship-to-ship combat maneuvering will play a key part in which spelljammer emerges victorious. The Maneuverability Rating (MR) of a ship determines how deftly it can move when in combat.
The MR of a ship ranges from 1 to 5 with 1 being the smallest and most agile such as the Elven Flitter, and 5 being surface ships that have been converted for space travel. Unlike ground combat movement can be made along the horizontal and vertical planes. This opens up many new possibilities for outmaneuvering your enemy.
The lower the MR of a ship the tighter it can turn, quicker it can accelerate from a stop and the shorter its stopping distance is. A spelljammer ship with an MR of 1 can make a 90 degree turn, accelerate to maximum SR or completely come to a stop all in the distance of one 500 yards (457 m) hex. For each additional level of MR an additional hex of distance is required to complete each maneuver. 

Maneuverability Rating

MR90 Degree TurnAcceleration Deceleration
11 Hex1 Hex1 Hex
22 Hexes 2 Hexes2 Hexes
33 Hexes3 Hexes3 Hexes
44 Hexes4 Hexes4 Hexes
55 Hexes5 Hexes5 Hexes
The distance that is required to complete maneuvers is determined by MR, but the time that is required is determined by SR. For example, a ship with an MR of 5 travels 2500 yards (2286 m) in the completion of a right hand turn. If that ship traveling at an SR of 5 (250 yards/ 228.6 m per round) it would take 10 rounds to complete the turn. 
Spelljammer ships are  also capable of moving straight up, straight down or in reverse. These maneuvers may only be initiated when the ship is at a complete stop. The speed for these maneuvers is one half of the maximum SR (round up). Moving in these directions follows the same rules for acceleration and deceleration as moving forward.

I think that pretty much does it for movement. I will probably end up being back here to fix some stuff once my group actually tries out some of this ship-to-ship combat. They always end up bringing up more scenarios than I can ever think of. For the next post I am moving on to some fun stuff; types of ships and ship weaponry.

5 thoughts on “Maneuverability!: Spelljammer 5e Conversion”

  1. You say there’s no Maneuverability “A” ships in the basic book, but any ship can be “Rigged” (at 100gp per ton) to increase MR by one degree. So the Elven Flitter could easily be MR “A”. Furthermore, you could strip two Armor Class off a ship to do the same thing, so the Dragonfly and Mosquito could also be “A” if you really wanted them to.

    In addition, the first published “get you into space” adventure for Spelljammer included the unique ship “Hummingbird”, which came out of the box with Maneuverability A (plus a “super magic missile” weapon fired from its beak).

    1. If you wanted to allow ships to be Rigged or to include the Hummingbird from Crystal Spheres you could just make the MR of the ship a 0. That would be a ship that could turn 90 degrees, accelerate or decelerate all without moving within its original hex.

      1. Err…I hate to do this to you… You mean 60 degrees. With hex facings, 360/6 is a change of 60 degrees, not 90.

        And yes, you could use the “MR 0” you mentioned in the original text, I’m just pointing out that MR A actually did exist in the game when it was first released. It wasn’t something that was included in a table but never got utilized (which *also* happened in 2e).

        1. I based all of the other MRs off of a 90 degree turn. The idea is to simplify the Spelljammer rules not teach a geometry course. If you want to use 60 go right ahead.

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