| This thesis is an investigation of the Naval Architecture aspects of Manganese Nodule mining from the deep ocean floor. The survey that was done included the existing theories on the formation of the nodules as well as their composition, physical characteristics and distribution. Some methods for lifting the nodules and the possible combinations of surface vessels are discussed. One of the methods was favoured; it uses submerged slurry pumps, a dredgehead and a steel pipe through which the nodules are raised to the surface. This method was examined in some detail and the examination includes mass, strength and drag considerations for the riser pipe and an estimate of the power required by the pumps, A few combinations of mining and transport vessels are proposed and they involve three different sizes of mining vessels. The chapter on transportation shows the relative advantages and disadvantages of each proposal. A comparison of the different hull forms was made and the different ways of transferring nodules at sea were examined. The preliminary design of the mining vessels for each combination was done and this included calculations on adequate freeboard, resistance and power, group weights and capacities, transverse stability, and the design of the propellers and side thrusters. The downtime due to bad weather conditions has been examined in detail for each one of the mining vessels for the area of operation. The economic section compares the costs of the different systems and is followed by a discussion of the results. It is not the purpose of this report to examine the processing of the nodules, but a section, based on existing literature on the subject is included. Also the legal and environmental aspects of deep sea mining are discussed. Among the conclusions are listed some features that need detailed examination. |
