The style here reminds me of WWII- and post-WWII-era British steam locomotives, a style I was thinking about trying out myself. This MOC may get a bunch of inspiration credit if that happens. Great work.
Haha, you're probably right. But I don't really care about physics, as long as it's a cool build and you've definitely managed that. If I didn't make it clear: I think this is great. Plus, you're the creator and you get to call the shots, like everyone gets to call theirs in their MOCs :) It's what makes it interesting, I think.
You are quite right Steef, there's also the problem that no-one can reach the furnace to keep it going, and that those hatches would flood the if ever opened, and a complete lack of light on the interior, and it has no ballast system to speak of, but hey, that's why it's fantasy right? That's also probably why I haven't seen any other steam powered subs...
That's pretty cool! I think the fire to produce the steam would use up all of the oxygen before it leaves the harbour (plus the steam bubbles would give away its position underwater), but that's another story ;)