While these intermediary sheets may have been pencil drawn, the NAVOCEANO guys did their finish work in ink. The pen of choice was the Koh-I-Noor Rapidograph. In the 1960s these were expensive finely fabricated precision pens from Germany. A set of these would produce various line widths, indicated by a color code on the pen caps.
A Rapidograph drew "india ink" up from a bottle through the cylindrical point into its ink reservoir with its internal plunger. A very fine wire inside the cylinder kept the ink flowing to the point. They were are a bit hard to keep clean if not in frequent use and worked better on mylar or hard surface paper. They were not really suitable for normal writing.
In these days of CAD drafting and electronic charts all this sounds anachronistic. Today the Rapidograph and other "technical pens" are more often used by graphic artists than draftsmen.
For whatever reason some the navy guys used to carry one or more Rapidographs in their pockets. You could tell from the ink stains on their shirts that they were pen fanciers. Perhaps they were viewed as status symbols, but only the quartermasters might have had any real need for them. I had several of various sizes that I got from the oceanographers. They had plenty of them.
Some of the navy logbooks were kept by guys using Rapidographs. I used a ball point; it worked better.