What I think is hilarious about this whole thing is trying to imagine the look of surprise on these idiots' faces when they see the 50 cal mount swing toward them....
Those oilers can easily be mistaken as a civilian ship even at moderate distance to the untrained eye....
They probably had absolutely no idea what they were in for until water around the boats started kicking up from incoming rounds!
Its just classic...

__________________
Uncle Sam
"What the hell is up with all the gauges?
Calling Captain Kirk, your ride awaits... Phasers on stun...."