Unfortunately don`t know the exact answer to your question, but I think at least some of the other species special ships require a special shipyard to build them. So maybe the Scimitar does as well? Perhaps go and see if you can build a special shipyard on one of your Starbases or as a separate megastructure?

Thanks man, I figured it out.

I have never played the base game and I have only played the Romulans, so I was really confused by all the guides for the federation trying to create an analogous ship yard or trying to use the base game wiki. Everything was making me think I needed a mega structure, but I didn't and I don't think the Romulans even have a version of utopia plantia.

I am sure someone will search for this again as the instructions in this game are not always clear, so here is what I did:


1) Finish the engineering research for Scimitar

2) Ensure you have researched large ship yard

3) Build a tier 4 Starbase

4) Build a normal shipyard on the top part of the Starbase, and on the bottom part there should be an option for a large ship yard

5) Add the Scimitar to your fleet using the fleet manager and reinforce your fleet or try to build the Scimitar directly at the large shipyard.

for some reason, even after the ship completed, the Scimitar did not show up in any of my fleets. I was pretty pissed but noticed several years later it managed to appear in my fleet.

I can't explain the delay, my fleet was waiting at the shipyards for the Scimitar to finish, but it eventually showed up.

Anyways, thanks for the reply and hope this helps someone else.

You need a special-level shipyard to make specialist ships such as the Scimitar; I've done it several times, but it requires a large-scale shipyard upgrade to the starbase that has the shipyard to do so.
It is oodles of fun, really devastating to enemies, but costly if it gets destroyed, so be careful to protect the Scimitar; think of it as "the Emperor's Ship" and consider that if it is destroyed, your empire falls apart, or has a dynastic constitutional crisis for short.