A cold atom system for an inertial navigation system (INS) demonstrator utilising atom interferometry is presented. Laser-cooled rubidium-87 atoms in a grating magneto-optical trap (gMOT) are used to measure acceleration along a single axis. This system demonstrates a novel technique in quantum-enabled navigation which could offer significant improvement in precision and reduction in the drift present in classical INSs. Ruggedised lasers and control electronics allow potential deployment in maritime navigation in global navigation satellite system (GNSS) denied environments. Considerations are made towards a pathway for modular expansion and development of the system to 6-axis operation.