We investigate utilization of the nonlinear coupling between the roll and pitch motions of wave energy harvesting vessels to increase their power generation by orders of magnitude. The proposed offshore wave energy generators are scalable and can be used for generation of large or small amounts of power for various sea platforms. The technology can be used at smaller scales to power marine sensor networks. The wave energy harvesters, investigated in this project, are different from the majority of wave energy harvesters, in the sense that, they do not need to be anchored to the seabed. This makes the proposed energy harvesters portable and fit for powering offshore sensors as well as sensor networks in shallow waters. Our proposed design utilizes the nonlinear coupling in the floating element to make the vessels undergo both pitch and roll motions in response to unidirectional waves. This significantly magnifies the gyration of the vessel and thus improves the power production by orders of magnitude.