You wonder how that massive hull can overcome the drag of the water to gain enough speed for ever getting airborne...
HUGE thick wing...massive low-speed lift...gain a bit of speed, less resistance in the water, gain a bit more speed, even less water to "push", next thing you know, you are picking up speed in the air!

But seeing them just sitting in the water floating like giants, it just doesn't "feel" like it could fly.