Model-scale podded propellers for maritime research

Podded propulsion has become a major technology in ship propulsion. Model-scale testing generally forms an essential part of the design procedure of ships equipped with podded propellers. Globally, a limited number of maritime research institutes (about 7) govern the global shipbuilding research market. For maritime research institutes, it is of major importance to be able to perform reliable model-scale tests of ships with podded propellers. A crucial step forward in model-scale testing of pods is the new innovated design of model-scale podded propellers described in this thesis. It describes this innovation that facilitates the current and future model-scale testing needs of the maritime industry. 1.1 Maritime research in the Netherlands Ever since man populated the Netherlands, the Dutch have challenged wind and waves. During history, it became part of the Dutch identity to investigate ways to conquer the oceans and to deal with the caprices of wind and waves. Over time, the focus gradually shifted from the bare struggle to survive towards profitable shipping in adverse conditions. In the latter era of hydrodynamic research, the Maritime Research Institute Netherlands MARIN has played a major role. MARIN has been dedicated to extending maritime knowledge in its broadest sense since 1932. Today, it has become an internationally recognised authority on hydrodynamics which is involved in many frontier-breaking research programs. Also, MARIN provides the maritime and offshore industry with state-of-the-art performance predictions, design consultancy and testing services [34]. Globally, MARIN is one of the leading institutes together with about 7 other institutes of similar size and importance. A major part of these research and consultancy activities is based on model-scale experiments in large water basins, so-called towing tanks (Figure 1.1 and Appendix A). In a towing-tank experiment, a model-scale replica of some hydrodynamic structure generally a ship is tested. This ship model is equipped with sensors that measure relevant important hydrodynamic quantities like resistance, propulsion forces, course stability and safety in waves. The ship model is exposed to a range of varying conditions during which the ship’s response is measured (Figure 1.2). These conditions may include various sailing speeds and propeller rotation rates, different wave conditions, steering patterns or even varying wind speed and direction. Model-scale measurements in towing tanks are used to predict full-scale quantities like propulsion forces, fuel efficiency and manoeuvrability. Scaling laws determine how these full1The focus of this thesis is on ships, therefore in the following, only ship models will be considered.