For the big boat picture I used a vector graphics drawing program called Micrografx Draw, which is basically abandonware - it's a nice easy to use program, but it's many years since it was supported, and it has some flaws that make some projects difficult. The big one, as far as the spaceship thing is concerned, is that occasionally things change size as the file reloads. This is a total pain if you are trying to do things to a consistent scale. It wasn't quite so important with the boat, but if the modular design idea I had is to work it will need to be scaled accurately.
Its big advantage, which is lacking from a lot of other programs, is that it's easy to work with banners and other projects that span several pages. That was very important for the boat, and will be vital for the spaceship thing.
Can anyone suggest something a little more reliable that has this capability, is fairly easy to use (e.g. not a fully featured CAD program) and hopefully isn't ridiculously expensive. So far I've tried Serif Draw and Open Office Draw, but neither seems to know about continuous multiple page documents. I suppose I could try setting up a custom page size or something, but it'd be easier to start out with a program that already has the capability built in.
How about Corel? It's ridiculously pricy but I may qualify for an educational deal or something. Anyone know?