Well, considering north and south are quite important on a few layers of meaning, then the third angled-pit adds in something that today's folk would be hard pressed to understand. It would take some understanding of beliefs and applications of beliefs, as well as terrestrial and celestial alignments in order to define what the third pit means.
Missing boats is a hazard in allocating a bow-point, but we have two aligned north-south pits where the the pits aren't specific to do with the sizes of their ends. Ends are small and large. So...which end would have the bow?
Then look at the third pit to assign the bow...if one gets it right.
if necessity is the mother of invention, why is there a monster under my bed?