The 2nd layer is for a subtle paneling overlay texture. If you look closely at ships they have a tiled texture that is superimposed over the top of the main texture. To get this 2nd layer working well, select all the polys on each of your meshes and use cube projection, scale your mesh up in the uvs a lot, about 80 times I found effective.
Also, sneak peak at my new ship

https://youtu.be/9L0TYh-MAkc
Hope this helps someone, but its for my reference as much as anyone else, I tend to forget stuff
