Yeah, shipping does seem to be one of the main applications where green hydrogen actually makes sense. Battery chemistry should improve to the point where basically no road transport should need anything else over the next 20 years (we're basically already there for most car applications, still some improvement needed for trucking etc., although maybe battery swaps is a better model there anyway). Ships need huge amounts of energy, but have the space to deal with hydrogen's poor volumetric density, unlike aviation, where I think synthetic fuel is a better option.