Wave drag significantly affects ship powering and speed prediction calculations, and the performance of sailing yachts. Linear Neumann-Kelvin ship wave theory is taken as a starting point for the development of a computational approach for predicting water flow about yacht hulls. Previous work by Baar and Price, Newman, and Doctors and Beck for the calculation of the Kelvin source and its derivatives and their use with panel methods is repeated, refined and extended. Consistent and accurate results are obtained for numerical tests and Farell's submerged spheroid test cases. Baar and Price's results for the Wigley hullform (which compare well with experiments) were not able to be duplicated in the present study, despite significant tests of both local and integrated solution values. The tests did indicate that the current implementation was behaving correctly, and gave wave resistance results equivalent to those from Doctors and Beck's study, to a level of agreement which contrasted sharply with the wide scatter in Chen and Noblesse's survey. These results remove to some extent numerical inaccuracies as a postulated source of the theory's difficulties, leaving the conclusion that Neuman-Kelvin theory, as it is currently understood, does not give satisfactory wave resistance results for realistic ship hullforms. These and further results lead to, and reinforce, the suggestion that the problem lies with the waterline integral term; a new treatment of this term may substantially increase the applicability of Neumann-Kelvin theory. The extensions required for modelling sailing yachts are considered. Investigation of three yacht design problems show that the developed model can predict, and partly explain, previously observed free surface effects. These 'relative' effects may be adequately predicted even though the absolute results appear less reliable. For the simplified parabolic yacht hullform tested, the sideforce is relatively constant over the speed range generally relevant to upwind sailing, and well modelled by the (zero Froude number) cosine squared (heel angle) relationship. The effects of a bulb, and heel (for the Wigley hullform), on wave resistance are shown. Suggestions for further work, calculation details, and tables of wave resistance and Kelvin source (and gradient) values are given. / Available in ProQuest Dissertation database. Subscribing Libraries only.

Wave drag significantly affects ship powering and speed prediction calculations, and the performance of sailing yachts. Linear Neumann-Kelvin ship wave theory is taken as a starting point for the development of a computational approach for predicting water flow about yacht hulls. Previous work by Baar and Price, Newman, and Doctors and Beck for the calculation of the Kelvin source and its derivatives and their use with panel methods is repeated, refined and extended. Consistent and accurate results are obtained for numerical tests and Farell's submerged spheroid test cases. Baar and Price's results for the Wigley hullform (which compare well with experiments) were not able to be duplicated in the present study, despite significant tests of both local and integrated solution values. The tests did indicate that the current implementation was behaving correctly, and gave wave resistance results equivalent to those from Doctors and Beck's study, to a level of agreement which contrasted sharply with the wide scatter in Chen and Noblesse's survey. These results remove to some extent numerical inaccuracies as a postulated source of the theory's difficulties, leaving the conclusion that Neuman-Kelvin theory, as it is currently understood, does not give satisfactory wave resistance results for realistic ship hullforms. These and further results lead to, and reinforce, the suggestion that the problem lies with the waterline integral term; a new treatment of this term may substantially increase the applicability of Neumann-Kelvin theory. The extensions required for modelling sailing yachts are considered. Investigation of three yacht design problems show that the developed model can predict, and partly explain, previously observed free surface effects. These 'relative' effects may be adequately predicted even though the absolute results appear less reliable. For the simplified parabolic yacht hullform tested, the sideforce is relatively constant over the speed range generally relevant to upwind sailing, and well modelled by the (zero Froude number) cosine squared (heel angle) relationship. The effects of a bulb, and heel (for the Wigley hullform), on wave resistance are shown. Suggestions for further work, calculation details, and tables of wave resistance and Kelvin source (and gradient) values are given. / Subscription resource available via Digital Dissertations only.

Wave drag significantly affects ship powering and speed prediction calculations, and the performance of sailing yachts. Linear Neumann-Kelvin ship wave theory is taken as a starting point for the development of a computational approach for predicting water flow about yacht hulls. Previous work by Baar and Price, Newman, and Doctors and Beck for the calculation of the Kelvin source and its derivatives and their use with panel methods is repeated, refined and extended. Consistent and accurate results are obtained for numerical tests and Farell's submerged spheroid test cases. Baar and Price's results for the Wigley hullform (which compare well with experiments) were not able to be duplicated in the present study, despite significant tests of both local and integrated solution values. The tests did indicate that the current implementation was behaving correctly, and gave wave resistance results equivalent to those from Doctors and Beck's study, to a level of agreement which contrasted sharply with the wide scatter in Chen and Noblesse's survey. These results remove to some extent numerical inaccuracies as a postulated source of the theory's difficulties, leaving the conclusion that Neuman-Kelvin theory, as it is currently understood, does not give satisfactory wave resistance results for realistic ship hullforms. These and further results lead to, and reinforce, the suggestion that the problem lies with the waterline integral term; a new treatment of this term may substantially increase the applicability of Neumann-Kelvin theory. The extensions required for modelling sailing yachts are considered. Investigation of three yacht design problems show that the developed model can predict, and partly explain, previously observed free surface effects. These 'relative' effects may be adequately predicted even though the absolute results appear less reliable. For the simplified parabolic yacht hullform tested, the sideforce is relatively constant over the speed range generally relevant to upwind sailing, and well modelled by the (zero Froude number) cosine squared (heel angle) relationship. The effects of a bulb, and heel (for the Wigley hullform), on wave resistance are shown. Suggestions for further work, calculation details, and tables of wave resistance and Kelvin source (and gradient) values are given. / Subscription resource available via Digital Dissertations only.

Wave drag significantly affects ship powering and speed prediction calculations, and the performance of sailing yachts. Linear Neumann-Kelvin ship wave theory is taken as a starting point for the development of a computational approach for predicting water flow about yacht hulls. Previous work by Baar and Price, Newman, and Doctors and Beck for the calculation of the Kelvin source and its derivatives and their use with panel methods is repeated, refined and extended. Consistent and accurate results are obtained for numerical tests and Farell's submerged spheroid test cases. Baar and Price's results for the Wigley hullform (which compare well with experiments) were not able to be duplicated in the present study, despite significant tests of both local and integrated solution values. The tests did indicate that the current implementation was behaving correctly, and gave wave resistance results equivalent to those from Doctors and Beck's study, to a level of agreement which contrasted sharply with the wide scatter in Chen and Noblesse's survey. These results remove to some extent numerical inaccuracies as a postulated source of the theory's difficulties, leaving the conclusion that Neuman-Kelvin theory, as it is currently understood, does not give satisfactory wave resistance results for realistic ship hullforms. These and further results lead to, and reinforce, the suggestion that the problem lies with the waterline integral term; a new treatment of this term may substantially increase the applicability of Neumann-Kelvin theory. The extensions required for modelling sailing yachts are considered. Investigation of three yacht design problems show that the developed model can predict, and partly explain, previously observed free surface effects. These 'relative' effects may be adequately predicted even though the absolute results appear less reliable. For the simplified parabolic yacht hullform tested, the sideforce is relatively constant over the speed range generally relevant to upwind sailing, and well modelled by the (zero Froude number) cosine squared (heel angle) relationship. The effects of a bulb, and heel (for the Wigley hullform), on wave resistance are shown. Suggestions for further work, calculation details, and tables of wave resistance and Kelvin source (and gradient) values are given. / Subscription resource available via Digital Dissertations only.

Wave drag significantly affects ship powering and speed prediction calculations, and the performance of sailing yachts. Linear Neumann-Kelvin ship wave theory is taken as a starting point for the development of a computational approach for predicting water flow about yacht hulls. Previous work by Baar and Price, Newman, and Doctors and Beck for the calculation of the Kelvin source and its derivatives and their use with panel methods is repeated, refined and extended. Consistent and accurate results are obtained for numerical tests and Farell's submerged spheroid test cases. Baar and Price's results for the Wigley hullform (which compare well with experiments) were not able to be duplicated in the present study, despite significant tests of both local and integrated solution values. The tests did indicate that the current implementation was behaving correctly, and gave wave resistance results equivalent to those from Doctors and Beck's study, to a level of agreement which contrasted sharply with the wide scatter in Chen and Noblesse's survey. These results remove to some extent numerical inaccuracies as a postulated source of the theory's difficulties, leaving the conclusion that Neuman-Kelvin theory, as it is currently understood, does not give satisfactory wave resistance results for realistic ship hullforms. These and further results lead to, and reinforce, the suggestion that the problem lies with the waterline integral term; a new treatment of this term may substantially increase the applicability of Neumann-Kelvin theory. The extensions required for modelling sailing yachts are considered. Investigation of three yacht design problems show that the developed model can predict, and partly explain, previously observed free surface effects. These 'relative' effects may be adequately predicted even though the absolute results appear less reliable. For the simplified parabolic yacht hullform tested, the sideforce is relatively constant over the speed range generally relevant to upwind sailing, and well modelled by the (zero Froude number) cosine squared (heel angle) relationship. The effects of a bulb, and heel (for the Wigley hullform), on wave resistance are shown. Suggestions for further work, calculation details, and tables of wave resistance and Kelvin source (and gradient) values are given. / Subscription resource available via Digital Dissertations only.

Inaug.-Diss.: Philosophische Fakultät: München: 1972. _ Contient des extraits en latin de la règle de St Benoit de Nursie. _ Bibliogr. p. 394-402. Index.

Hydrocarbon deposits in the form of petroleum, natural gas, and natural gas hydrates occur offshore worldwide. Electromagnetic methods that measure the electrical resistivity of sediments can be used to map, assess, and monitor these resistive targets. In particular, quantitative assessment of hydrate content in marine deposits, which form within the upper few hundred meters of seafloor, is greatly facilitated by complementing conventional seismic methods with EM data. The North-East Pacific Time-series Undersea Network Experiment (NEPTUNE) is an underwater marine observatory that provides power and network connection to a host of instruments installed on the seafloor on the Cascadia Margin offshore Vancouver Island. The observatory’s aim is to provide a platform for very long-term studies in which access to data is available on a continuous basis. For this thesis project, a transient dipole-dipole time-domain EM system was constructed and deployed on the NEPTUNE network with the goal of long-term monitoring of a well-studied hydrate deposit in the area. The instrument includes a source transmitter of electrical current and individual receivers to measure small electric field variations. The instrument is powered by the NEPTUNE observatory and data can be collected remotely by connecting to the instrument through the web. Data collected so far from the instrument are consistent with a resistive structure. The best fitting model from 1D inversion is a 36 ± 3 m thick layer of 5.3 ± 0.3 Ωm resistivity, overlaying a less resistive 0.7 ± 0.1 Ωm halfspace. Average hydrate concentration, deduced with the aid of ODP-889 well-log derived Archie’s parameters, is approximately 72% of pore space in the resistive layer, consistent with the very high concentration of gas hydrates (~80%) recovered from seafloor cores. The weekly collection of data from the instrument shows that the resistive structure has changed little since monitoring began in October of 2010.

Hydrocarbon deposits in the form of petroleum, natural gas, and natural gas hydrates occur offshore worldwide. Electromagnetic methods that measure the electrical resistivity of sediments can be used to map, assess, and monitor these resistive targets. In particular, quantitative assessment of hydrate content in marine deposits, which form within the upper few hundred meters of seafloor, is greatly facilitated by complementing conventional seismic methods with EM data. The North-East Pacific Time-series Undersea Network Experiment (NEPTUNE) is an underwater marine observatory that provides power and network connection to a host of instruments installed on the seafloor on the Cascadia Margin offshore Vancouver Island. The observatory’s aim is to provide a platform for very long-term studies in which access to data is available on a continuous basis. For this thesis project, a transient dipole-dipole time-domain EM system was constructed and deployed on the NEPTUNE network with the goal of long-term monitoring of a well-studied hydrate deposit in the area. The instrument includes a source transmitter of electrical current and individual receivers to measure small electric field variations. The instrument is powered by the NEPTUNE observatory and data can be collected remotely by connecting to the instrument through the web. Data collected so far from the instrument are consistent with a resistive structure. The best fitting model from 1D inversion is a 36 ± 3 m thick layer of 5.3 ± 0.3 Ωm resistivity, overlaying a less resistive 0.7 ± 0.1 Ωm halfspace. Average hydrate concentration, deduced with the aid of ODP-889 well-log derived Archie’s parameters, is approximately 72% of pore space in the resistive layer, consistent with the very high concentration of gas hydrates (~80%) recovered from seafloor cores. The weekly collection of data from the instrument shows that the resistive structure has changed little since monitoring began in October of 2010.