## 2 Current Status of Ocean-Going Ship Weather Routing Services
As shown in Figure 2, the shore-based platform integrates global weather observations/forecasts, electronic navigational charts, and shipping data to generate and recommend optimal initial routes through routing optimization algorithms. Upon voyage commencement, satellite-enabled bidirectional communication ensures real-time data synchronization between the shore-based platform and onboard terminals. This system delivers warnings for extreme weather events (e.g., typhoons, sea fog, and extratropical cyclones) by synthesizing real-time meteorological/hydrological data with numerical model forecasts. Concurrently, it dynamically updates optimal routes based on the latest forecasts of wind, waves, and currents. Post voyage, the platform conducts comprehensive evaluations of vessel performance throughout the voyage. In cases of disputes such as speed-related claims, it generates objective voyage audit reports with defensible evidence and recommendations, providing critical support for insurance settlements or arbitration proceedings. This closed-loop workflow--pre-voyage planning, during-voyage services, post-voyage evaluation, and dispute resolution--maximizes navigational safety and operational efficiency. Furthermore, the NMC developed a cloud-based weather routing service platform and mobile application system to enhance system stability and streamline service accessibility for client requests and real-time vessel status monitoring. To enhance the core technical capabilities of weather routing services, the NMC has conducted research on ship speed loss, developing three empirical algorithms for conventional vessel types. These algorithms have been integrated into weather route recommendation products to quantitatively assess the impacts of weather conditions on vessel performance. Concurrently, the NMC established a typhoon avoidance methodology and segmented avoidance strategies through the analysis of typhoon observations, track/intensity forecasts, and forecast error statistics. This framework optimizes navigation time by treating vessel speed and heading as variables, constrained by the minimum encounter distance between vessels and typhoon centers [34]. Furthermore, the NMC implemented a navigation risk forecasting system that evaluates voyage risks based on hydrometeorological parameters (e.g., wind, waves, swells, currents) combined with vessel-specific characteristics. The system generates risk visualization products to inform route planning and adaptive navigation strategies. Since relaunching its weather routing services in 2019, the NMC has served over 20,000 vessels. While NMC represents the primary national provider, other Chinese companies are also active in the market. These include Shanghai Haiyang Weather Routing Technology Co., Ltd. (Shanghai, China), Wuxi Ninceosmos Science And Technology Co., Ltd. (Wuxi, China), and Shanghai Maili Marine Technology Co., Ltd. (Shanghai, China) [25]. These private or semi-private entities are expanding their influence in domestic and international markets, often offering specialized weather routing solutions or focusing on specific market segments, thus contributing to the overall development of China's weather routing capabilities. However, detailed public information on the specific market shares and technical capabilities of these private providers remains limited.