User friendly ROR cards application designed for maritime industry by marinersplanet.comThe International Regulations for Preventing Collisions at Sea 1972 (COLREGS) are published by the International Maritime Organization (IMO), and set out, inter alia, the "rules of the road" or navigation rules to be followed by ships and other vessels at sea in order to prevent collisions between two or more vessels. COLREGS can also refer to the specific political line that divides inland waterways (subject to one set of navigation rules) and coastal waterways (subject to international navigation rules).