Thesis (M.S. in Information Technology Management)--Naval Postgraduate School, June 2003. / Thesis advisor(s): Monique P. Fargues, Russell Gottfried. Includes bibliographical references (p. 71-74). Also available online.

The lack of a necessary rational framework for assessing ship stability was the main concern of this research. The aim was to develop a rational philosophy and a logical procedure of assessing intact stability in order to ensure a consistent and unified approach to design for operation and for survival. The method uniquely brings together a linearised analysis for assessing a potentially dangerous roll motion with a probabilistic assessment of ship performance in rough seas on a standard test-track. This represents a significant advance on previous research. A novel feature of the analysis was that prediction of the extreme capsize roll motion was not attempted per se. Instead a reduced level of roll response termed "potentially dangerous" roll motion was selected (based on discussions with seagoing personnel) beyond which there was evidence that loss of the vessel is likely. Validation of the linear spectral analysis used in the simulations was performed using full scale trial results of a fisheries protection vessel. Provided that measured values of roll damping coefficient were used, the predicted values of extreme roll closely matched the maximum values experienced on sea trials up to the chosen value of critical roll angle of 30 degrees. Particular attention was paid to the realistic modelling of total system behaviour in rough seas. Families of wave spectra were used to represent the complete range of wave conditions encountered in nature. Avoidance and pacifying seamanship were incorporated based on the results of available trials data and discussions with serving masters. Independent (Bernoulli) trials procedures were used to calculate the cumulative probability of a critical roll motion being exceeded at least once during the vessel's passage through the test-track. The value of critical motion exceedance obtained was 5x10ˉ² for the fisheries protection vessel which has a large metacentic height and is reported to have good seakeeping characteristics.

This historical sociolinguistic study investigates the language of English seamen in the seventeenth century. Built on language data compiled from log books (Matthews 1935) and a survey of the maritime population from 1582, the author argues that the seafaring community had developed its own sociolect, which was based on the dialects of Southern England. Writers (e.g. Jonathan Swift, Daniel Defoe) and historians describe this “Ship English”: [S]ailors stood out from landsmen in a variety of ways. In the first place by their dress [...] Sailors were also recognisable by their speech, in which technical terms, slang and oaths had thickened to produce a private language. (Burke 1996:44-45) Following Ross and Bailey (1988), the author argues that this sociolect emerged from dialect contact (Trudgill 2004) aboard ship, with Southern dialects as the major input varieties: Several phonological features of Southern Early Modern English (e.g. diphthongization of Middle English /u:/ and /a:/, split of /u/ into /ʌ/ and /ʊ/, /w/-/v/ interchange) are pervasive in the data. Apart from being a interesting case study in itself, the results might be of importance for research on pidgins and creoles and colonial dialects: it has been argued (Hancock 1976) that nautical English has had a profound impact on the emergence of anglophone creoles because it – rather than some kind of Standard English – was the actual “superstrate” variety for most creoles. For the same reason, it might have influenced the emergence of the overseas varieties of English. / text

The Sea Peoples are generally assumed to be a loose confederation of clans that first appeared in the historical record in the 14th century B.C.E. Over a century of scholarship has puzzled over whether they were responsible for the collapse of several Late Bronze Age civilizations or simply one of several catalysts that put that collapse in motion. Many attempts have also been made to determine the origins of the various groups of Sea Peoples using textual and iconographic evidence, as well as the material culture of the Sea Peoples identified in Cyprus and the Levant. This material culture is characterized foremost by locally made Mycenaean-style pottery; as such, a considerable Aegean or Mycenaean presence has been argued in the multi-ethnic Sea Peoples coalition. The most important visual record that survives of the Sea People documents a land and sea battle against the forces of Ramesses III in the early 12th century B.C.E. and is recorded on the walls of the pharaoh's mortuary temple at Medinet Habu. In 1964 a connection was first proposed between the distinctive ships of the Sea Peoples in the Medinet Habu naval battle relief, with their high, angular stem- and stern- posts topped with outward-facing water-bird heads, and the vogelbarke, or bird-boat, of Late Bronze Age Central European religious iconography. Too little is still understood of both the vogelbarke tradition and the maritime abilities of Bronze Age Central European populations to conclusively state at this time that a vogelbarke-like vessel could have plied the waters of the eastern Mediterranean during the Late Bronze Age. However, additional archaeological evidence suggests a Central European mercenary presence in Mycenaean Greece during the period of Sea Peoples activity, as well as Central European participation in the multi-ethnic coalition reflected particularly in the material culture of the Sea Peoples identified in Cyprus. This evidence strengthens the possibility that the vogelbarke-like vessel some scholars claim to see at Medinet Habu is indeed not a "duck out of water."

Restoration of realistic animation is a critical part in the area of computer graphics. The goal of this sort of simulation is to imitate the behavior of the transformation in real life to the greatest extent. Physics-based simulation provides a solid background and proficient theories that can be applied in the simulation. In this dissertation, I will present real-time simulations which are physics-based in the area of terrain deformation and ship oscillations. When ground vehicles navigate on soft terrains such as sand, snow and mud, they often leave distinctive tracks. The realistic simulation of such vehicle-terrain interaction is important for ground based visual simulations and many video games. However, the existing research in terrain deformation has not addressed this issue effectively. In this dissertation, I present a new terrain deformation algorithm for simulating vehicle-terrain interaction in real time. The algorithm is based on the classic terramechanics theories, and calculates terrain deformation according to the vehicle load, velocity, tire size, and soil concentration. As a result, this algorithm can simulate different vehicle tracks on different types of terrains with different vehicle properties. I demonstrate my algorithm by vehicle tracks on soft terrain. In the field of ship oscillation simulation, I propose a new method for simulating ship motions in waves. Although there have been plenty of previous work on physics based fluid-solid simulation, most of these methods are not suitable for real-time applications. In particular, few methods are designed specifically for simulating ship motion in waves. My method is based on physics theories of ship motion, but with necessary simplifications to ensure real-time performance. My results show that this method is well suited to simulate sophisticated ship motions in real time applications.

Approved for public release; distribution is unlimited. / As an example of ships used as weapons (SAW), an oil tanker is hijacked and commandeered by terrorists to collide with a high-value maritime or shore target. If sunk or destroyed in a shipping lane as a result of a counter measure, the SAW’s collateral damage would severely disrupt the traffic flow in the shipping lane. To prevent such a disruptive catastrophe, non-destructive measures must be implemented to cause the SAW to deviate from its destructive path toward the target. One such a measure involves a strategic application of forces induced by water plume barriers (WPB) to the SAW. The goal of this thesis is to examine the feasibility of realizing such a measure. Toward this goal, a mission analysis, using the Singapore Strait as setting and petrochemical plants on Jurong Island as targets of a SAW attack, establishes the requirement on the deviation of the SAW path from its destructive course. The nominal WPB-induced force that satisfies the deviation requirement is estimated using ship hydrostatics. Solving the equations of motion governing the response of the SAW to a strategic application of a WPB-induced force yields the SAW’s motion, which is used to define a range of the WPB-induced forces and their application locations and durations that satisfy the SAW’s path deviation requirement. Parametric studies were conducted for a range of physically realizable WPB-induced forces and application times. The results demonstrate that, in principle, the objectives of this work are achievable. These results will be validated upon the completion of an on-going research by National University of Singapore. The range of the WPB-generated forces and their application durations serve as requirements to the generation of water plume barriers.

No description available.

Three interrelated topics in ship hydrodynamics - resistance, wave-making and wave decay - are investigated in an attempt to improve the accuracy of some simple methods used in the preliminary design of thin ships. Several published sets of data from classical and recent boundary layer experiments on flat plates are used to estimate boundary layer quantities such as thicknesses and eddy viscosities. These quantities are subsequently used to modify the hull shape and the free-surface boundary condition as a means of including viscous effects on wave-making and ship-wave decay. A recent technique is used to analyse 161 experimental flat-plate turbulent boundary layer velocity profiles, and a new skin-friction line is derived. Some practical methods are proposed for the numerical quadrature of integrals arising in thin-ship hydrodynamics. We demonstrate that for some integrals, rapid oscillation, rather than being a hindrance to accurate quadrature, can actually be beneficial if appropriate techniques are employed. We find that boundary layer displacement thickness effects on wave resistance are very small and can be safely ignored for full-size vessels. On the other hand, the idea of a detachment layer, an indication of where the boundary layer begins to thicken rapidly, is shown to have a significant effect on wave resistance. A modification to the Kelvin free-surface boundary condition is used as a means of including viscous effects on wave-making. Detailed comparisons of total resistance predictions and experiments are made for three model-size Wigley hulls. It is shown that inclusion of viscous effects smooths out the well-known humps and hollows in the wave resistance curves calculated using Michell's (inviscid) integral. Predictions of the total resistance of a model Wigley hull using Michell's integral and a simple skin-friction line are shown to be as good as those of a modern CFD computer code. Furthermore, the simple method does so in a very small time on an inexpensive computer. The effect of employing a form factor on the skin-friction is shown to improve correlations between resistance predictions and experiments. It has recently been proposed that a form factor should also be applied to the wave resistance. We show that good predictions are indeed possible, but that the use of a modified form of Michell's integral and an “appropriate" value of the eddy viscosity leads to even better agreement. Two existing wave-decay models are examined and a new formulation is suggested that combines the theoretical – 1/2 decay rate of transverse waves with the -1/3 decay rate of diverging waves. The effects of viscosity on ship-wave decay are considered. It is found that large values of the viscosity, of the order required to have a significant effect on wave resistance, lead to an over-damping of far-field waves at low Froude numbers. We show that it may be possible to get a rough estimate of the (ambient) eddy viscosity from an analysis of the decay of ship-waves with transverse distance from the sailing line, without resorting to computationally expensive Fourier transform methods. Three wave decay models are used to estimate the eddy viscosity from the behaviour of the wave decay. The model that uses the theoretical decay rates of transverse and of diverging waves is found to be slightly better at recapturing the original eddy viscosity than the other two models. / Thesis (Ph.D.) - University of Adelaide, School of Mathematical Sciences, 2009

There is at present great interest in large ships capable of carrying substantial cargo at speeds in excess of 40 knots. At the same time, there are large gaps in our understanding of the hydrodynamics, structural engineering, and economics of high-speed vessels. Monohulls, catamarans, trimarans, surface effect ships, and air cushion vehicles are considered in the present work. The total resistance of these vehicles is divided into separate components which are estimated using different methods. Skin-friction is estimated using Grigson's algorithm which gives much better predictions of flat plate skin-friction than the traditional ITTC method. Wave resistance of displacement hulls is estimated using Michell's thin-ship theory: a similar theory is used for the wave resistance of travelling pressure distributions. Several simple formulae are derived that can be used in the preliminary design stage of catamarans to estimate optimum demihull separation. Memetic algorithm techniques are used to find vessels with minimum (calm-water) total resistance. Optimal geometric parameters are found for vessels of 1200 tonnes under a variety of geometric limitations and constraints on upright stability, at design speeds of 50 knots and 75 knots. Estimates are made of the principal weight components of the optimal vessels. Empirical formulae for the efficiencies of powerplants and propulsors then enable estimates to be made of the maximum range, the cargo capacity, and the fuel consumption. / Thesis (M.Sc.)--School of Mathematical Sciences, 2005.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references (leaves 70-86). Also available via the Internet.