A significant majority of large fibre composite structures in the marine environment currently use a thermoset resin matrix. These materials have excellent durability in the sea, but are difficult to dispose of at end-of-life. After a rigorous selection process , methyl methacrylate and lactide monomers have been identified as potential thermoplastic matrix systems which can be manufactured using in situ polymerisation (ISP) during composite manufacture by liquid composite moulding (LCM) processes. LCM includes resin transfer moulding (RTM) for components up to about 3 m square, then Infusion under Flexible Tooling (RIFT for resins, or MIFT for monomers). The acrylic is a “drop in” for polyester resin, but lactide requires elevated temperature processes. At end of life, acrylic is lower in the recycling hierarchy.