A named vessel may be employed on a series of voyages called consecutive voyages against a single C/P. The vessel proceeds loaded from loading to discharging port only to return in ballast and repeat the following voyage on same terms and conditions until all the cargo has been shipped. However, separate calculations of freight and lay time are made for the individual voyages. It differs from a COA where the ship-owner can use any ship and the freight rates take into account the cost of ballast return voyage from discharge to load port.