The European inland waterway transport sector is a highly competitive one. The transport operators in this sector are mainly small companies with only one ship. Such companies have very few possibilities to distinguish themselves from their competitors. At the same time their main asset, their ship, is often highly standardized. In this thesis, it is researched to which extent the small companies in the inland waterway transport sector can improve their competitive position. This is done by minimization of the required ship rate and total logistical cost through optimization of the main dimensions of inland ships. To achieve this aim, a ship design model is developed. This model is used to create large series of designs in which length, beam and draught are varied systematically. These designs are used to develop a set of rules of thumb for steel weight, lightweight, building cost and cargo carrying capacity of inland ships with any combination of length, beam and draught. The optimal dimensions of a ship are a function of the properties of the transport chain in which it operates and the waterway on which it sails. Therefore, a second model is developed that allows assessment of the required ship rate and total logistical cost as a function of the main dimensions of the ship and the most important properties of the transport chain and the waterway. Finally, through an extensive scenario analysis flow charts are developed that allow estimation of the optimal ship dimensions as a function of the properties of the transport chain, the cargo type and the water depth.