Why do Navy crew address each other by nicknames?

This question makes it sound like you are culturally unaccustomed to nicknames. Nicknames are quite common in many cultures. Many jobs are in themselves a culture. For instance, the military, sports, construction, law enforcement, the mob, drinking (?), etc. It seems the more dangerous or physically difficult/demanding a job is, the greater the proclivity for nicknames. Although that last statement is more subjective and anecdotal than pure fact, it tends to hold true.

Nicknames tend to be derivations of actual names, positions, titles, mannerisms, physical traits or inside jokes stemming from memorable events. For instance, First Sergeants in the Army are often called Top. The CO is often called Boss and sometimes Daddy (not to their faces). The platoon leaders are often called LT or sometimes Toon Daddy. Medics are often called Doc. Someone with a long, complex name is sometimes called Alphabet or just the first initial of their last name. Military nicknames can tend to be a little more colorful than what is portrayed on TV. Tripod is a good example.

Charge in your example could be in reference to his position (not title) of NCOIC or the “Sarge in Charge”. Someone with a short, simple, single-syllable name like Bird is often not given a nickname unless they share a name with someone else. Although nicknames like Jonesy, Smitty, Scotty, Dino (my least favorite), and Birdie might buck this trend. Bomber is probably in reference to world renowned heavy-weight boxing champion Joe Louis (Barrow).