The three boats that stayed to help PCF 3 were there for about an hour in a waterway that was 75 yards wide.
There were NO reports of injuries from gunfire.
There were NO reports of Gunfire damage to the boats.
How do the Viet Cong miss 3 stationary 55 ft boats at less than 75 yards?
There are really only two possibilities:
1) They were unbelievably poor marksmen.
or
2) They weren't shooting at them.
I think I'll go with option #2.