If you look at the stern 1/3rd of the ship, you will see that part of the hull is as dark as the bow that you claim is fake.

I have no doubt that this is an authentic photo. I don't see anything wrong with the bow. Take something metal that is painted with a rough, worn paint job. Get part of it wet. You will se the wet part appears darker. Also, the line of the darker, wet area makes sense if the swell was coming at the bow and then passing under the ship. You can see where the water got higher up the bow when they met, then as the swell got far enough back, the ship began to rise up on top of it. The reflections on the water all match the ship. Look closely and you can even see a faint reflection of the 2nd group derricks from the bow. Also, go to Youtube and do a search for ships in storms. They most certainly can bob around significantly. If this was a fast moving swell, the closing speed between the ship and swell could mean the swell could pass well under the ship before the bow has a chance to fall back down. In looking at it again, it appears the ship is still climbing the swell, so the bow has no reason to come back down yet.
I see nothing in this photo that looks fake. The photographer was lucky enough to be in the right place at the right time. It's also possible that this had happened several times just before this photo, so the photographer had a chance to get ready and capture one.