i wouln't surgest sketchup, making quality ships for SS 08 is a hell of a lot harder then those profi programs,
you can only export models with sketchup pro, and once done all the black edges are exported as models too.
when you have models with a round shape you will clearly see it isn't smoothed and you can't smooth them with some reason, take a look at this image:
(if the image is scaled down, just copy and paste it to your computer and open it with windows viewer and zoom in on the bridge)
if you look at the ships bridge you will see it's made with sketchup, i had lucky becasue the model contained only one object so deleting the edges was very easy, but if you consider a whole fully modelled ship you are spending a week on it with deleting all the edges.
i surgest you 3ds max, find some good tutorials and once you know its easy to make high detailed ships
also a good one is cinema 4d, that one is easyer to texture with
you can trust me, i have modelling experiene with zmodeler, google sketchup, cinema 4d, 3ds max 8, catia, and a little bit autocad 3d