## 5 Analysis and Discussion
### Risk Performance Reasoning with Hidden Markov Model  
* The influencing factors of the reasoning performance were obtained through the demonstration, thereby providing a reference for optimizing the model parameters and the reasoning approach. According to the results and analysis of the risk performance reasoning, increasing the training data and identifying principal factors can improve the reasoning performance.
* Due to the great influence of cargo performance on the total risk performance of Handy bauxite carriers, high-risk cargo factors should be avoided. In particular, when the size of a bauxite carrier and the shipping environment or ship routing cannot be changed, the cargo quality related to shipping safety must be closely monitored, and a moisture content audit must be performed before loading, while rainproof measures should be ensured during loading and navigating.
* Compared with the effect of any single factor, the effect of the cargo, ship, and environment is more significant, leading to a transition of the total risk performance of Handy bauxite carriers. The process between subsystems is an important part of the shipping process risk control of Handy bauxite carriers. In order to ensure safety of shipping, it is essential to respond to risks timely and effectively based on accurate multi-source risk data, such as ship maneuvering, environmental information, and dynamic cargo information from the water ingress alarm system and the radar fluid-level meter fixed in the cargo hold. Therefore, it is essential to make full use of the Internet of things and artificial intelligence to develop intelligent risk monitoring sensors and forecasting equipment for shipping processes on Handy bauxite carriers.
* Based on the accurate historical data of principal factors and a more detailed classification of risk performance, short-term process risk reasoning with high-quality can be realized. Detailed shipping data of bauxite and Handy carriers include, but are not limited to, information from the logbook, which can be used in parameter learning to obtain more accurate parameters of the HMM. This will allow real-time monitoring and pre-warnings of cargo liquefaction and ship stability for the navigator onboard and ship manager ashore.
* In total, 91% of the accidents on international routes caused by the liquefaction of solid bulk cargo involve Handy carriers [47], which are usually between 80 m and 190 m in length. When a Handy carrier navigates at sea with a wavelength of 90-150 m and the speed is close to the wave speed, the ship ends up hogging and sagging, threatening the structural strength of the ship. The stability of the ship is, thus, greatly reduced.
* If possible, Handy carriers with bauxite should avoid sailing in heavy seas. In the stormy season, some special voyages of bauxite shipping could be conducted by larger bulk carriers or special ore carriers, which would have strong stability even when bauxite is liquefied. Appropriate working conditions of the main engine and ballast water can reduce the vibration intensity in the cargo hold, thereby reducing the risk of early cargo liquefaction, and obtaining earlier pre-warnings and for a better response time.