Charging big battery takes the same amount of time as charging small battery if charger's power is proportionally larger. E.g. charging Tesla at Supercharger takes same amount of time as charging phone using fastest phone charger.
(Similarly, refueling a ship is substantially more complicated than refueling an automobile.)
Maritime engineers and workers can get this job done.
Obviously there are better solutions, but that solution demonstrates feasibility with no further engineering work required.
To support a 48 hour recharge of the battery hypothesized upthread, you would only need to scale up this system by about 10x. Or attach 10 along the length of the ship. Or some combination of those options.
This is a non-problem.
Edit: Excuse me, but I misread the brochure. The existing system need be only scaled up by a factor of 2.5x to recharge a container ship in 48 hours.