Nuclear power is fine for larger ships, but impractical for smaller one, since the shielding is expensive and bulky.
But if gasoline can be made from seawater for $3.00, that is not just a boon for the Navy, but for the entire world. Since it is taking Carbon from the ocean, which would be returned when it is consumed, the net amount of Carbon added to the environment is zero or close to zero.
It would be a sustainable source of energy, which what we not use is not.