Inspired by the lattice structure of the unhydrated variant of the superconducting material NaxCoO2·yH2O at x = 1 3 , we study the t-J model on a honeycomb lattice by using an efficient loop-cluster algorithm. The low-energy physics of the undoped system and of the single hole sector is described by a systematic low-energy effective field theory. The staggered magnetization per spin f Ms = 0.2688(3), the spin stiffness ρs = 0.102(2)J, the spin wave velocity c = 1.297(16)Ja, and the kinetic mass M ′ of a hole are obtained by fitting the numerical Monte Carlo data to the effective theory predictions.