[Spaceships] Ship design rules - Can you have more or less than 20 systems?
 

On a cursory going over of the rules for laying out starships it says there are 18 slots, 3 per section and 2 core for a total of 20 system slots per ship. What happens if you don't have enough systems to have 1 in each or have more than 20? Does this ever happen? For less than 20 do you just add cargo systems to fill up the remaining?

I haven't tried to use the system to design a ship but the rules are confusing me a tad on a theory level. How does this work in practice?

Re: [Spaceships] Ship design rules - Can you have more or less than 20 systems?
 

Several formulae only work correctly if you assume exactly 20 systems.

Re: [Spaceships] Ship design rules - Can you have more or less than 20 systems?
 

Each system is 5% of the ship´s total mass. Having more or less systems simply means having a ship with more or less than 100% of it´s total mass. In other words, no. If you use fewer hardware you have less mass, but still 100% of it. If you use more hardware, you have more mass, but still 100% of it. It may help to think less of 20 systems and more of 20 units of 1/20 of total mass each.

If you only want to use less than 20 systems on - for example - a SM+10 ship you must either add cargoholds to get to 100%, or you can check whether a SM+9 ship might do the job. Roughly speaking, 6 SM+10 systems equal one SM+9 ship, as a each size level equals roughly a tripling of mass.

Re: [Spaceships] Ship design rules - Can you have more or less than 20 systems?
 

For more than 20 you can always assume that some pieces are designed for craft one SM smaller, essentially giving you 2 additional slots. This is not recommended for drives or fuel tanks, however, as those have formulae designed for 20 slots.

I've used the sub-slots for Habitat, Passenger Seating, and Cargo Holds, but it's not a stretch to apply it to Armor, Refineries, Mining, Reconfigurable, Open Spaces, and even Control Rooms (if you don't mind lower sensor and computer ratings).

Re: [Spaceships] Ship design rules - Can you have more or less than 20 systems?
 

Okay. I read the part about each system being 5% of the mass(i.e. 1/20 of total) and the 1-3-10 ratio of increasing SM levels but wasn't sure about if those numbers were set to always work out to be 100% of the rated mass with 20 systems.

A similar question is it says the Hi Power systems require 1 point per system, so for systems which have a range like [4-6!] this requires 3 power points correct?

Re: [Spaceships] Ship design rules - Can you have more or less than 20 systems?
 

You can get the same system more than once (in fact you just about have to).

Re: [Spaceships] Ship design rules - Can you have more or less than 20 systems?
 

Yes, a system written as [4-6!] requires 3 power points. In a RAW design, that's because it's a group of 3 high-power systems.

If you really wanted to build inter-SM ships by using more or less than 20 systems, you could do it...the rockets are the easy part to fix. Just multiply acceleration by 20/N, and set delta-V to the 'one tank' delta-V times:
log(N/(N-F))/log(20/19)
Where N is the total number of systems and F is the number of fuel tanks.

The armor requires assumptions...I think you want to multiply the DR per system by (20/N)^(2/3).

...Then your HP are wrong (you could recalculate them), and your random damage allocation system doesn't work right anymore. So it's probably better not to.

Re: [Spaceships] Ship design rules - Can you have more or less than 20 systems?
 

People were intimidated by 3e's Vehicles book. Now we've got the simplified Spaceships for 4e, and people want their beast back. Nothing in life can bring eternal happiness . . . :)

Re: [Spaceships] Ship design rules - Can you have more or less than 20 systems?
 

That's exactly it. I was thrilled with the potential for design systems in UT 4e; when they were stripped out, I wept.

Re: [Spaceships] Ship design rules - Can you have more or less than 20 systems?
 

If it helps, think of each ship as having 20 locations and each location always consists of 5% of that ship's mass.

When you buy a system you're deciding what goes in that location but even if you don't put anything there the location still exists.