Pirates?

The new w:TI class supertankers are over 1200 feet long (379m). A 50 cal machine gun isn't super accurate, so assume you'd need one every 300 feet of length. That's 5 gun positions PER side. 10 in total. Say you only have 5 of those positions manned at any given time (You have to see the enemy coming). Now you have to have these people in shifts, lets assume standard 8 hour rotations, so now you're up to 15 "high trained marksmen" (whom BTW wouldn't use a machine gun, marksmans would use rifles). Even well qualified machine gunners aren't cheap. So now you've gone from a crew of about 30 to 45. You've probably also DOUBLED the cost of personnel for each and EVERY trip.

You have no sympathy for people (the crew) who are just trying to make a living like everyone else. People who aren't paid to fight pirates, they are just making decent wages (certainly not overly well paid for what they do). You are a cold, heartless bastard.