Conversion Rules, Space Opera to Alternity v1.1.2

These rules are intended to allow a Gamemaster to fill a gap in Alternity's space vessel lineup, namely capital ships, by converting large Space Opera ships in Alternity. While ships desgined using Space Opera's desgin sequences in Book2 will work fine the rules are mainly intended for use with Sheldon's Compendium of Space Vessels 2, as it has many laarge military vessels already made up.
Note: These guidelines divide PL7 into early, mid, and late. These are shown by: PL7e, PL7m and PL7l, respectively.

For small ships convert their tonnage to Dur on the following table and redesign using Alternity.
Space Opera Tonnage Alternity Dur (Civilian/Military)
100- 8/10
250- 16/20
500- 24/30
1000- 32/40
2500- 40/50
5000- 48/60

For larger ships just convert the stats and don't worry too much about whether they're possible or not.


DUR = Space Opera DC/25 round to the nearest whatever if it pleases you.


These become Deflection Inducers. BattleScreens of +15 or more only suffer a +1 penalty for a Critical Failure, get triple the bonus against non-space weapons and double vs. Standard space weapons. Those of +30 or more also get +1 extra to their bonus vs. Attack.


Space Opera BattleArmour  Alternity Armour Type
0 - +3 None
+4 Light Polymeric
+5 Medium Polymeric (TL7/PL7e)/ Light Alloy (TL8+/PL7)
+6 Light Cerametal
+7 Heavy Polymeric (TL7/PL7e)/ Medium Alloy (TL8/PL7)/ 
 Light Neutronite (TL9/PL7l)
+8 Medium Cerametal
+9 Heavy Alloy (TL7/PL7e)/ Medium Neutronite (TL8+/PL7)
+10 Heavy Cerametal
+11 - +12 Heavy Neutronite
+13 or greater Heavy Neutronite x (BattleArmour value/7, rounded to the 
 nearest 0.5)

Nova Guns

N*200+ are considered to be Particle Accelerators, unless the manufacturing entity uses MegaBolt Torpedoes, in which case they are considered to be Plasma Cannon. Small Nova Guns should be taken off the following table, as should standard ship's weapons when converting. Twin turrets in Space Opera ships should be taken to be single turrets in Alternity, and triple turrets as single turrets with a -1 step to hit bonus.
Nova Gun Calibre Alternity Weapon
N*25 Point-Defense Gun
N*50 Mass Cannon
N*75 Mass Cannon
N*100 Plasma Cannon
N*125 Plasma Cannon
N*150 Particle Beam
N*175 Particle Beam

For civilian Hardpoints and the smallest Hardpoints on military ships use the following rule: Half the Hardpoints will become Point-Defense Guns, and the other half will be read off the table above. Obviously this means that N*25 calibre Hardpoints will all be Point-Defense Guns.

Long Range = Plasma/PAW long range + (Nova Gun maximum range - 500)/50
Short and Medium Range retain the same ratio to long range as the standard Alternity weapons (round down).

Damage = Plasma/PAW damage x (Nova Calibre/100, round to the nearest 0.5)

Accuracy = +0 vs. Large Ships, and +1 vs. Standard Ships.

MegaBolt Torpedoes

Considered to be very large Mass Converters, with corresponding Acc and special effects. Their range is the same as that of a Mass Converter (very short). All MegaBolt Torpedo installations are considered single forward mounted guns.

Damage = Mass Converter damage x (MegaBolt Calibre/100)

Accuracy = +0 vs. Large Ships, and +1 vs. Standard Ships.


Large Space Opera StarTorps are considered to be large missiles with large Matter Cannon shells as warheads. As a result they the smaller ones aren't too accurate. The ST*775s have good ECM systems, however and are thus quite accurate against large ships. None of the larger StarTorps are very accurate vs. Standard sized ships however, because they are not very maneuverable.
Calibre Range Damage Acc
ST*157 ST*157s are considered to be normal missiles, with all stats as the particular type
 of missile loaded.
ST*257 10/20/30 Matter Cannon x2 +1 (+1 vs. Standard Ships)
ST*375 12/24/36 Matter Cannon x4 +0 (+2 vs. Standard Ships)
ST*775 16/32/48 Matter Cannon x8 -1 (+2 vs. Standard Ships)
The ST*775 takes two phases to reach long range, and thus doesn't make it's attack roll until the phase after it was fired if the target is more than 32 Megametres away at the time of firing.

Maneuverability and Acceleration

For military ships take the Space Opera TISA acceleration and cross-reference it on this table:
TISA Acceleration Maneuverability
+5 +3
+5/+15 +2
+5/+20 +1
+10/+20 +0
+10/+30 +0*
+15/+30 -1
+15/+45 -2
+15/+60 -2*
+25/+50 -3
+25/+75 -3*
*-1 bonus to maneuverability due to stabilization.

Acceleration and cruising velocity should be read off the Alternity table as if the ship is using Induction drives (as that is exactly what it is in fact now using).

Some classes of ship should probably get a -1 bonus for stabilizers and/or high top speed e.g. Terran Battle Cruisers and perhaps MegaBolt armed ships.

For civilian ships take a look at their acceleration and their top speed relative to the top speed for their tonnage.


Take the ship's FTL speed in LY/Day and round to the nearest 5. That is the ship's Starfall range in Light Years.

Computer Grade

Convert based on the following table:
Total Marks of all ship's computers Alternity quality
1 - 11 Marginal
12 - 14 Ordinary
15 - 17 Good
18+ orany total from 3+ computers Astounding


Civilian: Take your best guess based on the ship's range vs. The maximum sensor range for that TL, and the ship's role.
Military: Military ships will, as a general rule, have all available sensors for their PL, barring the Remote Network. The presence of a Remote Network and the number of uses it has will be dependent on the type of vessel, its role and the designer's nationality. As a guide use the table below:
Ship's Class Number of Uses
Commerce Raider  6
Fleet Corvette N/A
Destroyer N/A
Destroyer Leader 6
Light Cruiser 12
Heavy Cruiser 6
Fleet Cruiser 9
Battle Cruiser 15
Battleship 12
BattleStar 18

Add 3 uses at PL7l or later, and subtract 3 uses at PL7e (if this drops to less than 6, no Remote Network is installed).


Like sensors, pretty much whatever seems reasonable.

ECM, etc.

For a Space Opera ECM value of 5+ give Chaff. For 10+ give Chaff, plus a Jammer, and multiply the number of Chaff launchers and Jammers by 1 per 'full' 2.5 the ECM value is above 10.

Damage Control:

Space Opera Alternity
None None
Standard Ordinary
Superior Good
Comprehensive   Astounding
StarFleet Astounding+
(can perform full repairs out of combat)

Other Features

Ships will usually have enough small craft, Escape Pods and Reentry Capsules for the whole complement plus passengers.

The cargo Dur of a ship will equal a percentage of its durability equal to the percentage the cargo tonnage occupied in the original Space Opera design.

Powerplant: The rating after type (if any) is the surplus power available as a percentage. This gives a surplus in case of battle damage, and also allows some maneuvering and firing during Starfall.

Boat Deck: The number and type of small craft carried. Use some general equivalent. For the fighter flight deck assume that 100 m3 of Space Opera flight deck means 1 Dur of hanger in Alternity.

Cost: As a very general rule Space Opera ships cost 10 - 20 times their Alternity equivalents.


Divide the ship into 5-10 compartments. There should be 1 Command, and enough for most essential systems to be split between two compartments (this doesn't matter so much for a civilian ship). There should be a separate compartment for each weapon battery, with the StarTorps in with the 1st Secondary Battery.

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Last updated: 22 November 1998 
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