Almost every piece of maritime moon lore is really about tides, light or the state of the air, which is why so much of it works better than the farming equivalents.

A sailor's moon beliefs had to survive contact with a sea that would kill him for being wrong. Spring tides at new and full are real, earthshine does indicate clean air, a halo does mean a front. The rules that persisted at sea are disproportionately the ones with a mechanism, which is a quiet argument for how folklore gets filtered.