## 1 Introduction
However, these methods are relatively expensive, and after these processes, there is waste in the form of solvents that must be managed in some way. From an ecological point of view, material recycling, otherwise known as mechanical recycling, is often the preferred form of waste processing. The addition of shredded waste as fibers or fillers for new products does not force production plants to drastically change their production technology. The biggest disadvantage of this type of recycling is the formation of a new material, which after its end of use, becomes waste for reuse. The second most popular method of recycling yacht hulls is incineration. As a result of this process carried out in municipal waste incineration plants, glass fibers end up in slag, which contains heavy metals and, therefore, must be stored in safe landfills so as not to pollute the environment. During the combustion process, toxic gases may be released (methane, ethane, ethylene, acetylene, ethylbenzene, carbon monoxide, etc.) The currently used recycling technologies of post-consumer composite waste reinforced with glass fiber, in the opinion of international organizations [22], comply with the provisions of EU directives. The best recycling option for composite yachts is a composite recycling process that can enable the supply of cement kilns [22]. This method uses waste as both raw materials and energy (fuel). In the publication [23], published by the European Cement Society and in work [24], representatives of the European composites industry recognized this technology as the recommended method of waste management in glass fiber-reinforced durolasts. The policy of the European Union, in connection with Directive 2008/98/EC, aimed to minimize the amount of waste and its harmful impact on the environment. In addition, the above-described significant problem related to the disposal of vessels caused a search for alternative materials and the construction of new ones [13; 18; 25]. One of the concepts for this was the use of natural fibers for their construction. The advantages of this solution are the low cost of obtaining raw material and its production (in the form of fabrics and mats), reducing the weight of the finished product, and the possibility of producing units using the same methods as traditional composites. In addition, the replacement of synthetic fibers with natural fiber should make it possible to reduce the amount of waste needed for landfill after the recycling process through the use of energy recycling with energy recovery. One company in the yachting industry that is beginning to experiment with natural reinforcement is the Dutch yacht manufacturer Contest Yachts [26]. The Sunreef Yachts Eco Company has also set new standards in the field of sustainable design by introducing composites based on flax and basalt in the yacht-building process to its offer [27]. On the other hand, [PERSON] et al. [28] studied bamboo laminates for application on the hull's panel. A review of the latest applications of polymer composites reinforced with various fibers in vessels (e.g., warships) was made in the work of [PERSON] [29]. Trends of their development, and also of natural composites, e.g., based on wood, were indicated there. Currently, the use of natural composites in the construction of yachts is still in the experimental phase and requires further research and technological development and material properties. Despite all the advantages of natural composites [30], it is necessary to assess the impact of their use on the safety of the crew (in accordance with the International Convention for the Safety of Life at Sea--SOLAS, or the International Code for the Application of Fire Test Procedures--IMO FTP Code), especially during a fire outbreak. Testing the fire resistance of these materials can also contribute to the assessment of the possibility of energy recycling. The description of the phenomena accompanying the flammability test of materials was applied to the assessment of engineering plastics in terms of the safety of their use.