The Colombian ship fires at the Nathan James, who is sailing straight for her, however the shell comes from the starboard side and splashes midships.
The academic paper Chandler shows had a grade of "B+" written on it when shown in the first episode.
However the grade may have been on a paper sticker, which had been removed before Chandler showed it to the other senior officers.
When Captain Green started addressing the crew aboard the Nathan James, Slattery was still at the command centre in Florida. Then suddenly he was standing behind her as she continued speaking to the crew.
The 'Colombian corvette' is actually a Dutch 'De Zeven Provinciën-class' frigate. Four of these were built and are in service with the Royal Netherlands Navy, none have been sold to foreign navies. It also sports coast guard stripes and lacks a pennant number, both highly unusual for a ship of this size.
The Nathan James' previous shell splashed midships, very close to the port side of the Colombian vessel, suggesting the problem is with elevation (or distance). Leading the target more than they already did would result in splashes in front of her bow, rather than the direct hits that follow.