Heavy Cruiser: Canarias
Light Cruiser: Almirante Cervera
Light Cruiser: Navarra
Gunboats: Dato, Canalejas & Castillo
All models from Navwar's 1/3000 range. I used artistic licence for the gunboats. They're some kind of tiny, crap destroyer possibly from the Ironclads range.
Here's some heroic Republican Air Force, or La Gloriosa, planes on their way to show the rebels the error of their ways:
I found this site which details several major and minor naval engagements during SCW. They also provide some simple rules. I'll be doing a play-test or two soon; results and pictures when I have them.
Salud y Républica!