A system for monitoring restraint of one or more containers that have been restrainedly secured to a container ship by one or more restraint members, the system comprising: the one or more containers ; the one or more restraint members for restraining respective ones of the one or more containers, wherein the one or more restraint members each comprise a turnbuckle member configured for fastening to a fixed point on the container ship via a shackle or fork member ; a plurality of sensors each configured for monitoring one or more of a compressive or tensile stress or strain in one of the one or more restraint members wherein each of the plurality of sensors is fitted on the shackle or fork member of the turnbuckle member for monitoring stress or strain in one of the turnbuckle members ; a controller for periodically interrogating each of the plurality of sensors to ascertain a value of stress or strain detected by the respective sensor; and a computing device coupled to the controller, characterized in that each of the plurality of sensors comprise a Fiber Bragg Grating (FBG) sensor configured for measuring the stress or the strain in one of the turnbuckle members ; wherein the one or more containers that are secured by restraint members having sensors for monitoring one or more of compressive or tensile stress or strain are a subset of containers on the container ship; the computing device determines whether the value of stress or strain ascertained by the controller satisfies a threshold condition in the FBG sensors. the one or more containers ; the one or more restraint members for restraining respective ones of the one or more containers, wherein the one or more restraint members each comprise a turnbuckle member configured for fastening to a fixed point on the container ship via a shackle or fork member ; a plurality of sensors each configured for monitoring one or more of a compressive or tensile stress or strain in one of the one or more restraint members wherein each of the plurality of sensors is fitted on the shackle or fork member of the turnbuckle member for monitoring stress or strain in one of the turnbuckle members ; a controller for periodically interrogating each of the plurality of sensors to ascertain a value of stress or strain detected by the respective sensor; and a computing device coupled to the controller, characterized in that each of the plurality of sensors comprise a Fiber Bragg Grating (FBG) sensor configured for measuring the stress or the strain in one of the turnbuckle members ; wherein the one or more containers that are secured by restraint members having sensors for monitoring one or more of compressive or tensile stress or strain are a subset of containers on the container ship; the computing device determines whether the value of stress or strain ascertained by the controller satisfies a threshold condition in the FBG sensors. each of the plurality of sensors comprise a Fiber Bragg Grating (FBG) sensor configured for measuring the stress or the strain in one of the turnbuckle members ; wherein the one or more containers that are secured by restraint members having sensors for monitoring one or more of compressive or tensile stress or strain are a subset of containers on the container ship; the computing device determines whether the value of stress or strain ascertained by the controller satisfies a threshold condition in the FBG sensors. <EOS>