Every conversation about decarbonizing container shipping starts with the engine. Dual-fuel LNG or dual-fuel methanol, ammonia later, and a newbuild order that locks the answer in for twenty-five years. It’s the decision that gets the press release. For the compliance math a European carrier actually faces this decade, it isn’t the decision that moves the number most. FuelEU Maritime has been in force since January 2025. It doesn’t regulate fuel choice directly.