Military Ship Design

by Adam Moffett
Author’s Note: This write-up is by Adam Moffett, incorporating ideas worked on collaboratively by Adam Moffett, Sean Moffett, Darren Moffett, and Eric Moffett in our parents’ basement around 1993(?) or so.


First off, I don’t know if TSR’s writers really had a system in mind when they came up with stats for the UPF and Sathar ships in Knight Hawks. I do know however, that players or referees who want to make a new type of warship will find it helpful to have something to go on. What my brothers and I did some years ago was look at how weapons are applied to civilian ships (using the minimum hull size, “MHS” number of the weapon), and extrapolate a similar system for military ships.

In Knight Hawks, each weapon and defense system has a minimum hull size or MHS value. That value represents a cost associated with installing that weapon, where the ship builder gets 1 unit per hull size of the ship. For example, a torpedo launcher has an MHS of 5 so a hull size 10 ship can install 2 of them. Spending over your limit causes severe penalties to ADF, MR, and cargo capacity.
If you add up the number of points spent on UPF/Sathar ships which are described in the book, you’ll find that they spend way over their MHS limits without any penalty at all. This is attributed to more advanced technology which is only available to the military.


  1. Ammo and Other Costs - The book provides no cost for ammunition (other than monetary). Why then, do the gigantic battleships only carry 8 torpedoes? Why not carry 200 and not have to worry about running out? I have assigned MHS values for ammo to account for this. I have also assigned values for upgrades which provide extra Hull Points and changes to ADF/MR.
  2. Atmospheric Flight Penalties: The Assault Scout Problem - When plotting the number of points spent on weapons and ammo versus the hull size of the ships, it was obvious that the assault scout was out of line with the rest of the universe. On the chart below you’ll see that the assault scout does not fit on the curve with the rest of the ships. Then it occurred to me that the assault scout is also the only military starship made for atmospheric flight, and that perhaps that is the source of its penalty.

    To fly in an atmosphere, a ship needs to be balanced and streamlined and it needs control surfaces. It may also need reinforcing to survive a high speed lift off and heat shielding to survive the initial descent through the atmosphere. My position is that all of these additional things limit the amount of mass and volume that can be devoted to weapons. So for ships hull sizes 2-5 I have provided a heavy penalty for making the ship capable of atmospheric flight. Hull size 1 gets it for free…..that’s one advantage to being so little.
  3. Hull Points, ADF, & MR - Some ships don’t fit the normal amount of Hull Points, ADF, or MR for their size, so methods of trading MHS for any of these values were created. I also added methods to trade them for each other in some cases.
  4. Is MHS truly “minimum hull size”? - The Warriors of White Light introduced a pirate corvette, which was a hull size 4 ship equipped with a laser cannon (MHS 5). So apparently some minimums are more minimal than others. If the referee wants to allow a larger weapon on a smaller ship that wouldn’t be allowed using civilian rules, then I say go for it.
  5. Technology differences: The Heavy Cruiser Problem - Like the assault scout, the heavy cruiser does not fit on the curve with the rest of the UPF ships. I attribute this to their age. The book states that heavy cruisers were battleships which were reclassified as heavy cruisers when the new and larger battleships were built. Therefore I say that all heavy cruisers are old ships and have weaker capabilities due to inferior technology. Referees should feel free to apply penalties to MR/ADF/MHS/HP or whatever else makes sense to ships which are very old, or also to account for technology differences among factions. You may also notice that UPF frigates and destroyers come out just slightly better than what you could build with these rules (they have 4 or 5 extra MHS points), so referees should also feel free to grant bonuses to very new and/or high tech ships.


This table gives the number of MHS points that ships of various hull sizes receive toward armament and defenses.

Hull Size 
Number of
MSH Points 
1-10  Hull Size * 8
11  82 
12-20  Hull Size * 7 


Base hull points are the same as civilian ships: 
Hull Size * 5


DCR is calculated the same way as for civilian ships, but then doubled.
Hull Size * 3 + 20 * 2

Example: HS 3 ship has 3*3+20*2=58


This section lists the cost in MHS points for the various parts of the ships:

Original KH Items

These are unchanged from the original rules.

Defense or Weapon MHS Point Cost 
Reflective Hull 
Masking Screen 
Electron Screen 10 
Proton Screen  12 
Stasis Screen 10 
ICM Launcher 
Laser Cannon 
Laser Battery 
Proton Battery 10 
Electron Battery
Disrupter Cannon 12 
Assault Rocket Launcher
Rocket Battery
Torpedo Launcher
Mine Spreader  7
Seeker Missile Rack


Ammo Type MHS Point Cost 
 Extra water for Masking Screen
 Batch of 4 ICMs
 One unit of ammo for any weapon

Reinforced hull

Add up to 60% more hull points using the following cost scale; this is a much better buy for smaller ships, though it is also worthwhile for battleships because their base hp is so high.

Hull Size HMS Point Cost 
1-6 1 per each 10% increment 
7-14 3 per each 10% increment 
15-20 10 per each 10% increment 
* Each 10% boost will provide at least 1 HP

Example: UPF Frigates have a base of 25 hull points. A 10% boost is 2.5 extra hp. After buying the extra hit points the maximum number of 6 times, the UPF Frigate now has 40hp (25 + 2.5 + 2.5 + 2.5 + 2.5 + 2.5 + 2.5)


Sacrifice MR or ADF for extra hull points. This is only worthwhile for ships whose speed is less important than their durability, such as minelayers and assault carriers.

Hull Size HP Gained Remaining MHS Points 
1-10 5 HP 1 MR or ADF lost 
11-20 10 HP  1 MR or ADF lost 
* Round down ADF/MR

Trans-atmospheric Penalty

This is the cost in MHS points to streamline the ship for atmospheric flight. This is not possible for ships larger than Hull Size 5.

Hull Size MHS Penalty Remaining MHS Points 
No penalty 
 4/8 penalty
3 5/8 penalty9
4 6/8 penalty8
5 7/8 penalty 5

Fighter Bays

The cost of a fighter or shuttle bay is 8 MHS points. I think the difference would only be in how the bay was equipped. Ships can of course carry shuttles or fighters docked to the outside, but then any repairs or maintenance require extra vehicular activity which we can assume is more time consuming.

Extra MHS

If you still need more room for weapons and equipment you can trade off maneuverability or hull points for a little extra space using the following two rules:
  1. Overloaded: Trade 1 MR or 1 ADF for a 10% MHS bonus. This does very little for small ships, but big ships have less MR and ADF to spare, so it’s tough to justify using this option. This rule was made to make the Assault Carrier fit the rest of my model.
  2. Light Hull: Trade 10% of ship’s original hull points for a 10% MHS bonus. Also a hard trade to justify. None of the UPF ships do this. Can’t be used with reinforced hull, and unlike reinforced hull this option can only be taken once.


I think it is unclear how the number of crew members on a SpaceFleet ship is arrived at. I think a bare minimum crew would consist of the following: 
  • 2 pilots (so someone can be at the wheel day and night) 
  • 1 gunner per weapon 
  • 1 operator per defense system (except reflective hull) 
  • 1 technician per engine 
  • 1 commanding officer 1 navigator
On small ships like assault scouts, jobs can overlap, so the captain could also be a pilot, an engineer can double as a gunner, etc. I would probably double everything for any ship of frigate size or larger. People will need downtime so they don’t burn out.

As the ship gets larger, you’ll need to add more techs for everyday maintenance, a handful of marines for security, and probably at least one medic. Once you have more enlisted people you’ll need more officers too. Referees should try to use common sense as to the number of people required to crew any ships designed by them or by players.


You may notice that I did not assign credit costs to any of the new ship features. Since military ships are built by governments, the exact cost of its armor and weapons will not usually be relevant to player characters.


Maybe. Changes in MHS versus hull size are almost linear, where changes in the ships’ volume and surface area are exponential. So if it’s a matter of physically stuffing the weapons into the available area, then everything is way off. A destroyer should be exponentially mightier than a frigate in that case.

On the other hand, mass should also increase exponentially with hull size, and the fact that large ships get less ADF and MR means that thrust does not increase to match. My explanation for the difference then is that it’s really a matter of how much extra mass we can attach to the hull without impairing its speed more than its own size already does.
But then again it’s also more about having fun and keeping the game balanced. If the player characters’ frigate is exponentially weaker than their enemy’s destroyer then there is very little difference that heroic characters can make in the battle. So a linear progression of strength is more appropriate for gaming.


My brothers and I added extra factions to the game outside of the Frontier Sector, having a system to design ships allowed us to differentiate factions without just making stuff up. Equally cool is that the players were able to design the ship that their characters were assigned to. It was fun and gave them more of a stake in their ship’s survival.