Ishmael decides that the equipment on the whaling boat deserves one more special chapter—this time, it’s about the crotch.
The "crotch" is a long notched stick used as an upright rest for the harpoon handle.
Usually there are two harpoons in the crotch, both connected to the line—but this can be really dangerous if the harpooneer misses with one of them, because then there’s a free harpoon attached to the line that’s whizzing around. They have to throw it overboard and let it drag in the water, hoping its blade doesn’t cut anything important, like the line, or somebody’s arm.
On a major whaling voyage, each boat might have two spare harpoons swinging around like this on each of four boats—making a total of eight or ten random swinging blades for everyone to avoid in the middle of the hunt. Yikes.