Steam-and-steel naval warfare without gunpowder

What would an age of steam and steel look like if gunpowder had never been invented?

Navies would probably emphasize ramming and boarding, backed by steam-powered crossbows, mechanical rapid-fire projectile weapons, and other ways to pierce hulls without guns.

Without gunpowder, steam propulsion and steel construction would still create fast, durable warships, but their weapons would develop along different lines. Ramming, boarding, and projecting spikes or bolts into an enemy hull would regain importance. Steam-powered winches could load very large crossbows, while mechanical rapid-fire systems might produce dense close-range arrow fire. Later follow-ups consider pneumatic guns and steam-launched torpedoes as awkward alternatives, while mechanical projectile weapons still appear better suited to reach and reliability. Aircraft operating without explosives would push designers toward radio control and fuel as possible ways to damage a target. The idea is deliberately speculative, yet it separates the effects of propulsion and construction from the independent development of explosives. Navies would adapt available energy sources to the tactical need to penetrate, disable, or board an opponent.