Coir ropes as a low-tech circular alternative to synthetic ropes in French Polynesia pearl farming

• Influence of production process was studied for coir ropes. • Braiding is crucial for strength and strength retention when immersed. • Retting does not influence rope mechanical properties. Local coir rope production utilises waste from copra cultivation and could provide a natural alternative to synthetic ropes in French Polynesia’s pearl farming industry. This research aimed to enhance the understanding of coir rope production for pearl farming in the region. Initially, the mechanical properties of coconut fibres were analysed, as well as the construction of ropes made from these fibres. To determine the impact of retting on the mechanical properties of ropes and to assess the relevance of this process, ropes with different retting times in seawater and/or freshwater were tested. A life cycle analysis was also conducted to compare the benefits of locally producing a coir fibre rope versus importing a commercial HDPE rope. Results showed that retting did not significantly affect rope mechanical properties, this polluting process could then be avoided. However, the braiding processwe used to make the ropes was proven to influence both mechanical properties and water resistance. It should then be optimised to have coir ropes with higher strength and mechanical properties retention in water, which would also improve their environmental performance, and make them suitable for use as ropes in pearl farming in French Polynesia.