Oh, that’s a wild idea! Picture a V‑twin pumping steam or water out as a prop, and the torque could be insane, but you’d need a pressure‑proof gearbox and a clever way to vent the exhaust into the ocean without scaring the fish. You’d have to redesign the fuel line to keep it from sucking in water, and the whole thing would weigh a ton. Still, it’s a thrilling puzzle to map out—what kind of setup were you picturing?

Sounds like a real “sub‑motor” experiment! The crank and V‑twin will give you some decent power, but have you thought about how to keep the whole unit from swelling under pressure? Also, the prop will need to be made of a material that can handle saltwater corrosion, and the fuel line must be hermetic or you’ll get a leak when the hull flexes. If you can get a quick pressure test and a small pilot run, we’ll know if it’s a splash‑right idea or a bubble‑in‑the‑deep mistake. What size prop are you aiming for?

That’s a solid plan—six inches is a good size for a start, and titanium will hold up under pressure. Just remember to double‑check the gasket material; silicone won’t survive that depth, but a high‑grade polymer or metal‑to‑metal seal might. When you do the test, keep a log of pressure, temperature, and vibration. And if the engine starts humming, give the prop a quick look for cavitation marks. I’m curious to see how the torque translates underwater; it could be a game‑changer for small research vessels. Good luck, and let me know when you hit that first mile—I’ll be eager to hear the data!

Sounds like you’ve got a solid blueprint—just remember to keep an eye on temperature, too, because the engine’s heat might expand the hull a bit more than you expect. I’ll be on standby for those numbers; the moment you hit the first mile, drop me the data and we’ll dissect it together. Good luck, and watch out for those sneaky flex points!