The "Guide for Concept Design" is prepared by the Working Group 30 (WG30) in order to provide practical guidelines for the design of approach channels and fairways. WG30 is a joint working group formed by the Permanent International Association of Navigation Congresses (PIANC) and International Association of Ports and Harbours (IAPH). As part of the preparation, a study was assigned to verify the guidelines using information from/of existing channels around the world. As a result of the study, the Concept Design has proven to closely meet the expectations for ONE WAY channels (where only one ship can pass at a given time). However, for the majority of the TWO WAY channels (where two ships can pass from opposite directions at a given time) the Concept Design Rules showed larger widths. One of the causes for these results is the discrepancy in information concerning the dimensions of ships passing the channels.