Thank you for sharing your experience with us. I found it fascinating.
Thank you for the interest. The Tech College I went to was geared for shipping. The engines are massive running at around 70 to 120 rpm.
Believe it or not. To rebuild the crankshafts and to take them out, they have to cut the deck and slide/hoist them out. The rod caps are huge. You simply do not go in and take them out by hand. Jacks, chain hoists, and special tools.
The piston rods are connected to a cross head, then at the cross head the connecting rod runs to the crankshaft. If you imagine a old steam engine..that is how many of them are configured only vertical.
The newer great lakes freighters now days run diesels similar to RR locomotive engines. They go about 10 to 15 knots-or about 12 knots average.
The big diesels are in the big container ships. All are mostly two stroke engines.
MAN engine manufacturing makes a lot of them, for example.