I am thinking of extending my engine room model to include a "fake" boiler. Anyone any thoughts on what type of boiler boiler paddle wheelers used ?  i.e. Cylindrical horizontal or rectangular scotch boiler type?  Also I am assuming that most of them would have used timber for fuel rather than coal.
Bob

Most western river steamboats hat locomotive-type horizontal boilers due to their comparatively low weight.
I highly recommend Alan Bates' two standard books "The Western Rivers Steamboat Cyclopoedium" and "The Western Rivers Engineroom Cyclopoedium" including a multitude of drawings invaluable for the modeller.

Moritz