James E. Kelley, in an article published in 1979, built a much stronger case for his interpretation of the islands on the chart. Kelley describes the development of navigation, noting that by the end of the thirteenth century sailors in the western Mediterranean were guiding their ships by the use of the magnetic compass, the traverse board, and a marine chart (Kelley 1979, 18). Kelley believes that some fifteenth century portolan charts include information obtained from voyages to America (Kelley 1979, 29-30). With regard to the 1424 chart he argues: "The island of santanazes has a large, north-pointing bay on its southeastern coast, suggestive of the Bay of Fundy. The form of this bay is quite unlike the usual inlets seen in portolan charts. The bay is labelled ysya=issa (Latin)=rising (of tide), the best known characteristic of the Bay of Fundy. The bay’s entrance is at the correct latitude relative to the western European coast, namely Biarritz in France, an indicator consistent with the assumption that Atlantic mariners did latitude sailing in the fourteenth century and earlier" (Kelley 1979, 30). The term "latitude sailing" refers to the practice of finding the desired latitude and sailing on that latitude during the voyage—this was feasible because mariners could find their latitude at sea by using astronomical instruments and noting the positions of the polestar (Stella Marinus, the star of the sea) and constellations.

Kelley made more specific identifications: "The island Antilia would seem to represent the U.S. coast from northern New Jersey into North Carolina, including the whole of Cheaspeake Bay region" (Kelley 1979, 30). Kelley also suggests that the idea that the word Antilia was formed from the Portuguese words "anti and ilha" with a meaning of "island in front." This idea may have to be further checked as the name of Anticosti Island in the Gulf of St. Laurence, once thought to derive from the Spanish "anta costa," is now known to be of Amerindian origin.