Britain without coal

[Myth]

If Britain hadn't had coal, do you think the other powers of Europe would have known to begin using their coal reserves to eventually power Ironclads?

Seeing as how many discoveries happened simultaneously or within the span of a year from each other, I'd say no particular one is truly exclusive, except for maybe the theory of relativity. So yeah, at some point they would have.

Also, from Wikipedia:

In the 18th and early 19th centuries fleets had relied on two types of major warship, the ship of the line and the frigate. The first major change to these types was the introduction of steam power for propulsion. While paddle steamer warships had been used from the 1830s onwards, steam propulsion only became suitable for major warships after the adoption of the screw propeller in the 1840s.

Steam-powered screw frigates were built in the mid-1840s, and at the end of the decade the French Navy introduced steam power to its line of battle. The desire for change came from the ambition of Napoleon III to gain greater influence in Europe, which required a challenge to the British at sea.

The steam propeller is not spaceflight. Someone would have figured it out. And even though the Royal Navy was working on an armoured frigate of some sort, it was the French who actually introduced the first ironclad warship.