The aim of this thesis is to explore various means of increasing the efficiency of charterparties, both from an economical and an environmental perspective. When the speed of the vessel is reduced, the decrease in bunker consumption is directly proportional to the reduction of the emissions; seemingly a win-win situation is achieved. Consequently, both the environment and the company paying for the bunkers generally profit from reducing the speed of the vessel. From a legal perspective, speed reduction clauses are nonetheless quite complicated. A slow steaming clause might be contrary to a due despatch obligation in the charterparty and in a bill of lading. Consequently, a third party holder of a bill of lading might be able to hold the carrier liable for not performing the voyage with due despatch. In order to properly evaluate the risks and benefits of incorporating a speed reduction clause, these issues are assessed in this thesis.