Nephi’s Sea-Crossing Cords are the cords with which Laman and Lemuel bound Nephi while traveling by sea. They “did take me and bind me with cords,” treating Nephi “with much harshness” (1 Nephi 18:11).
After Laman and Lemuel had bound Nephi so that he “could not move,” the compass prepared by the Lord “did cease to work” (1 Nephi 18:12).