The navigable channel width calculation in JTS 165-2013 Design Code for General Layout for Sea Ports does not cover the values of wind and current drift angles γ and the ship drift factor n under conditions where cross-current exceeds 1.0 m/s and crosswind exceeds Force 7.A study is conducted on the concept and calculation of γ.The relationship between n and γ is fitted,and a theoretical model for determining γ by inputting wind speed and current velocity is built.Calculations are performed for typical representative ship types,and the results are compared and validated against ship maneuvering simulator tests and existing code values.This demonstrated the accuracy and legitimacy of the theoretical model for calculating γ.The influencing factors and variation patterns of γ are analyzed.Building on the existing code,the values for γ and n are extended and refined for conditions where velocity of cross-current is 1.0(not included)-1.5 m/s and crosswind is Force 7(not included)-9.The relevant findings have been incorporated into JTS 165-2025 Design Code for General Layout for Sea Ports,providing guidance and reference for the design and calculation of navigation channels in coastal ports.