Shaw's thread is a good one and nearing a milestone!
I have uploaded a complete plan of the 1st season set
here.
The first season Engine Room was longer than the later design. I worked out the length of 24' by comparing the width of the corridor to the length of the Engine Room (click for larger version):
I know from examining set plans (with measurement callouts) that the corridors are 8' wide, so the rest is easy!