Back on subject...
Solar has its applications in ships (the batteries on our life boats are 100% solar charged) and having more uses in the future (trickle charging the bridge APSses, simplifying wiring of hard to get sensors/cameras etc).
But the Solar Freaking Deck is quite silly.
My current vessel has 3 x 6000 kW engines, 10000kW of power usage is routine.
A m2 of solar is 200W...
If a rectangular "solar deck was added in the style of a Chitose-class aircraft carrier,
It would get 140x28x200 watts or 784kW in ideal conditions, and with Solar Roadways junk tech much lower efficiency, it's useless.
As for large cruises ships, the Symphony of the seas (might as well go big, and made in my home town) has:
- 4 × 14,400 kW (19,300 hp) Wärtsilä 12V46F
- 2 × 19,200 kW (25,700 hp) Wärtsilä 16V46F
She probably needs, at minimum, 70% of the capacity of two of the smaller engines at standstill with passengers onboard (she most probably has those engines split in pairs with automatic blackout recovery) and 80% on the total capacity on the larger engines cruising (those engines don't like low loads).
In any case, it becomes clear how insignificant a few 100 square meters of partially shaded silly sun tech is...
And how crazy cruise ships have gotten.