Automatic communication between computer systems on board and ashore is a necessity. At this stage it is limited to simple exchange of information – the data transmitted in the messages. It is expected that it will take the more complex form soon, allowing the dialogue, the transmission of intentions and conducting negotiations. To make it possible, it is necessary to build suitable ontology, describing the processes of communication at sea. To apply this ontology in information systems it is necessary to present it in a proper representation. This paper presents a method of generating a representation in form of XML-Schema based on the ontology built with the use of Protégé program