I'm looking at the period drawing and noting that the perspective on the sternwheel frame circle is off: if you can't get your perspective correct on distant rotating machinery while multiple people are trying to kill you with heavy weapons, you aren't worth much as a combat sketch artist, are you.
Dang, I wish my hands would allow me to build paper models, she looks good.
These river ironclads, tinclads, and cottonclads, sure have a variety of interesting shapes.