Final answer:
Official navy letters typically follow specific military guidelines that favor serif fonts for their classical and professional appearance, though the exact preference was not provided.
Step-by-step explanation:
The preference for font and pitch in naval letters is not explicitly mentioned in the context provided, but what can be understood is that there are two basic types of letterforms: serif and sans-serif. A serif font is characterized by the small "tails" on the edges of letters, which are often seen as more classical or refined. Conversely, a sans-serif font, like Helvetica, lacks these tails and tends to convey a more modern feel. The choice of font in official documentation like naval letters would likely depend on specific military regulations or guidelines which typically favor cleanliness, legibility, and formality, often leading to the use of serif fonts for their traditional and professional appearance.