A method of maintaining positioning between vessels includes monitoring a relative position between a storage tank vessel and a shuttle tanker with a control system in operative communication with the vessels. Also included is inputting physical property data relating to the storage tank vessel and the shuttle tanker to the control system. Further included is processing environmental condition data with the control system. Yet further included is controlling at least one positioning action to be taken by the storage tank vessel and the shuttle tanker with the control system in response to positioning calculations conducted by the control system based on the physical property data and the environmental condition data. Also included is maintaining an angular differential within a predetermined limit with the at least one positioning action.