The classic frequency-based transit assignment method of Spiess and Florian has been previously used as the basis for a maritime assignment model that employs liner service frequencies instead of fixed sailing times. This paper focuses on the management of empty containers, a topic of great interest to the maritime logistics community given the effects of the global trade imbalance. We present a novel repositioning algorithm that can be applied across a large network of services by a single or several co-operating shipping lines