@athanasios: I'll be glad to adopt the sprites for the ships if you have all the possible views from it... Otherwise I'm creating my own.
@michael blunck: the idea to have a narrow gauge orientated set is to have eye-candy. I'm not really sure if I'm going to implement standard-gauge trains in my set... I could do that, but the only rule then is that I have to concentrate on private railway rolling stock. This is because, also there, the choice in vehicles is also narrowed, and they are most likely to be specialized in only a few tasks and speeds.
It could be something like this:
Narrow-gauge: powerful engines, low price/costs, low speeds (app. 80km/h);
Standard-gauge: weak engine, high price/costs, low speeds (app. 100km/h);
Ships: strong engine, extremely low price/costs, high capacity, quite low speeds.
I'm also intend to make this set compatible with TTD, not only OTTD. In TTD though, it would probably be harder to play.
@Wile E. Coyote: that will help a lot! Is it okay if I adjust some of the sprites to get them to blend in well with the other sprites in this set? They seem a tad too light IMO.