why would a portolan map be inappropriate as a resource for navigating land routes?

A portolan map is inappropriate for navigating land routes because it was designed specifically for sailing along coasts at sea, not for overland travel.

What a portolan map is

• A portolan is a medieval sea chart focused on coastlines, harbors, and sailing directions rather than inland geography.

• It is covered with compass roses and rhumb lines (straight lines showing constant compass bearings) to help pilots steer ships between ports.

Why it fails for land routes

• Land interiors are barely drawn: inland areas often have minimal detail, sometimes just decorative features or place names without usable roads, terrain, or distances.

• There are no latitude–longitude grids or modern topographic information, so you cannot accurately fix positions or plan complex overland paths.

Sea-focused, not land-focused

• The map is literally “centered on the sea,” with land pushed to the margins and treated as context for coasts, not as a navigable landscape.

• Features critical for land travel—mountains, passes, rivers as barriers or routes, road networks—are missing or schematically shown, so overland navigation would be misleading and unsafe.

Information gathered from public forums or data available on the internet and portrayed here.