This link is handy for anyone that complains about our motorhome fuel consumption. And the ships are probably bringing all the computer kit over from Asia that people use to post their complaints about fuel consumption!
I work in whats left of the diesel engine manufacturing industry, mainly marine, rail traction, and power generation. Yes, I'm told that this crank was made from a single billet. Although large, the manufacture wil remain the same as a small crank. Each journal will be individually drop forged untill all the journals forged. Then the billet will be gripped whilst other journals are twisted by rotating through 60 degrees untill the crankshaft take on
its more common apperance. Machining done in a number of stages, rough turning, finish turning on a lathe. Next comes grinding of the main bearing diameters followed by the bearing journal. Next the crank is balanced on machine called a dynomometer, sometimes a crankshaft will bend during
manufacture, so it needs to checked and straightened if needed. Finally the crank is checked for any cracks which may cause it to fail durng service.
I've worked on some very large marine engines in my time, but nothing on this scale. No wonder they are called Cathedrals.