Somewhat belatedly - and with apologies for my tardiness - here are some pics of my riverine craft with my Airfix figures by way of comparison. The tape measure in the background gives some clue to the dimensions of the vessels, but I will give some actual figures in another posting.
The heading picture was set up to show the potential for introducing a pseudo-perspective to pictures using the disparate scales between figures and models. The CSA artillery here, by the way, are a couple of scratch-made 20pr Parrotts, and a Whitworth muzzle-loading rifle. Well, that's what I call them anyhow...
In the above picture you can compare very roughly the relative sizes of the vessels. The tape measure in the background is only a rough guide, as the Carondelet should be only 180mm (representing 180ft) in length, as is the nearer steam ship. The gunboat has a 52mm beam.
The CSS Tennessee is 200mm long by 45mm wide (approximately); the tugboat 100mm long; the mortar barges 60mm. All the vessels are intended to be 1:300 scale, or close to it.
Note the comparison between the 1:76 scale figures and 1:300 scale vessels. Quite a difference. But together on a table top in combined operations, they look surprisingly compatible.
Finally, I've included a picture of republished copy of Thomas Scharf's book (originally published c.1887) History of the Confederate States Navy. Considering the lack of resources, and the enormous odds the CSN had to contend with, they did surprisingly well, and this volume is commensurately interesting.