## 5 Conclusions  
This paper proposed a trusted communication method for ship CA decisions based on blockchain technology and then a distributed multi-ship CA decision support scheme based on blockchain technology. The results provide an effective solution for communicating CA logic in encounter scenarios to ensure secure and efficient communication during short-term, one-time ship encryption. As a result, they can help select better (more trustworthy) nodes to maintain critical knowledge during ship CA and to judge trust in unknown members. In the final case studies, it can be seen that all encounter ships actually achieve a \"centralized\" CA decision-like behavior through CA communication, which can be economically better and safer than the traditional distributed CA decision.  
The blockchain-based collision avoidance method proposed in this paper used blockchain to record the dynamic subjective trust perception of each encountered ship towards each other without assuming a central database that everyone acknowledges. Through block generation and dissemination, each encountered ship can effectively perceive and rank the credibility of participants in the broadcast network. As a result, individual ships can adopt appropriate strategies to deal with CA practices. Consequently, the socio-technical system of social attributes is strengthened to achieve self-governance in the  
Figure 11: Ship trajectories in case 2.  
encountered scenario. Another issue that needs to be clarified is that this paper mainly considers the problem of ship collision avoidance based on blockchain communication, so the main contribution of the paper lies in how to make effective collision avoidance communication rather than decision-making. In fact, collision avoidance decision-making and trusted communication are two equally important parts of the collision avoidance process, where the content of decision-making is communicated through communication. Therefore, the case study section also adopts this perspective by considering only whether safety can still be ensured under successful and incomplete communication. The results show that the approach in this paper is effective.  
To further improve the proposed method, further research can be conducted to address the following limitations: (1) the proposed scheme does not consider the unstable network connections between randomly assembled nodes, where propagation may fail to reach and cover a majority of nodes; (2) the generated blocks may not be synchronized across the entire network; (3) the majority of the investigated multi-ship CA communication system must be non-malicious entities, although it should largely reflect the reality of the shipping industry.  
Conceptualization, Y.C. and T.W.; methodology, Y.C.; validation, T.W., Y.X. and Y.W.; formal analysis, Y.C.; writing--original draft preparation, Y.C. and G.Y.; writing--review and editing, T.W., Y.X. and Y.W.; visualization, G.Y.; supervision, T.W. and Y.X.; project administration, Y.W.; funding acquisition, T.W. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Key R&D Program of China (grant number 2021 YFB1600400), the Hubei Natural Science Foundation (grant number 2021 CFB324), and the National Natural Science Foundation of China (grant number 52101403).  
Not applicable.  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.  
Not applicable.  
The authors declare no conflict of interest. The funders had no role in the