The boys were ensconced in the ship’s library, a cozy room with a fireplace, and two large armchairs, many books, a giant spinning globe, and atlases and maps. The boys had spread out some nautical charts before them and were gazing intently at the mass of symbols and squiggly lines with shapes in tan, blue and white patterns. Fergus explained.
“You see the white bits here,” Fergus said, gesturing to blobs on the chart, “this is the area most desirable for sailing. The blue bits are the areas of sea best avoided.”
“But that doesn’t make any sense since water is blue.”
“True. And see these tiny numbers? They indicate how deep the water is in that very spot. Sometimes in feet, but it could also be meters, or fathoms, which is another unit for measuring depth. And see these dotted lines around something? That shows a rock or other problem–something you had be sure you don’t run into. Hmmm. I don’t understand this bit, the purple colored lines–what’s a ‘Cable Area’ I wonder?”
The boys looked closer.