It appears that Swift Boats operate much like a Tank Platoon only on water. You may not be on same vehicle as a man but you're operating close enough to get to know all members of the platoon.
Plus, several of the SBVs have said that at the end of the day they were all billoted together or in close proximity. They ate together and actually lived together. You get to know a person pretty well .. even if you aren't on the same boat.