Many onboard ship operations demand full radio coverage over the entire ship, not only indoor, but also from the interior spaces to the other decks. Onboard a ship, specifically in the upper decks, radio wave propagation is subjected to fading that would impede the quality and reliability of data links and communication. One example is the performance of unmanned aerial vehicle (UAV) data and communications links. The purpose of this thesis is to analyze, model, and simulate some communication scenarios that occur on naval ships using Urbana. Starting from known inputs (frequency, ship compartment geometry, material properties, propagation computation model, and antenna type), analytical results reflecting the propagation mechanisms and coverage area are presented. Variable inputs can then be optimized to achieve a desired signal distribution for a specific shipboard environment. The ship models were created by Rhino, a well-known Windows-based computer drawing software. The values of the signals received on the different points in the main deck are computed for different frequencies and powers. The results are used to draw conclusions of the deployment of antennas on the ship as well as operational aspects such as UAV flight paths.

Sea piracy has infested the seven seas throughout history. In modern times, the United States has paid little attention to piracy because the nation's isolated vastness has protected the shipping industry from maritime crime. But the events of 9/11 have changed the lens through which America views security. This thesis investigates modern day piracy and links between piracy and terrorism in order to determine implications for U.S. maritime security strategy. Specifically, the maritime environment in Southeast Asia and associated maritime security policies are researched because a sizable proportion of the world's sea piracy occurs in that region. U.S. maritime security policy is also evaluated. / US Navy (USN) author.

MBA Professional Report / Approved for public release; distribution is unlimited. / The purpose of this MBA project was to complete a cost-benefit analysis of refueling via pipeline versus refueling via barge at Pearl Harbor, Hawaii. The alternatives are (1) refueling via a combination of pipeline and barge (status quo), (2) refueling via a single pipeline, and (3) refueling via barge only. The objective was to compare the three alternatives, choosing that alternative that provides the greater net benefit and most efficient use of resources. The analysis involved data collection of labor costs, pipeline operations (flow rates data, costs of repairs, and operational costs), barge operational costs, and environmental protection costs. This Cost Benefit Analysis (CBA) will be valuable to personnel with approval authority who make decisions on the merits of future pipeline projects. This CBA can be used to evaluate other Navy bases' refueling operations worldwide. / Lieutenant Commander, United States Navy

Approved for public release; distribution is unlimited / The purpose of the Littoral Combat Ship is to provide the Navy with an affordable, small, multi-mission ship capable of independent, interdependent and integrated operations inside the littorals. The Littoral Combat Ship will be designed to replace high-value Naval assets when conducting high-end missions such as littoral Anti-Submarine Warfare (ASW), Mine Warfare (MIW) and Anti-Surface Warfare (ASuW) as well as perform low-end missions such as Humanitarian Assistance (HA), Non-combatant Evacuation Operations (NEO) and Maritime Intercept Operations (MIO). In order to accomplish these missions and successfully counter the enemy's littoral denial strategy, the Navy has stated the Littoral Combat Ship must incorporate endurance, speed, payload capacity, sea-keeping, shallow-draft and mission reconfigurability into a small ship design. However, constraints in current ship design technology make this desired combination of design characteristics in small ships difficult to realize at any cost. This thesis (1) analyzes the relationship between speed, endurance, and payload to determine the expected displacement of the Littoral Combat Ship, (2) determines the impact of speed, displacement and significant wave height on Littoral Combat Ship fuel consumption and endurance, and (3) analyzes the implication of findings on Littoral Combat Ship logistics. / Lieutenant Commander, Supply Corps, United States Naval Reserve

In developing designs for high speed vessels, the engineer must account for the response of the ship in the environment while operating at mission essential speeds. This thesis presents a seakeeping analysis of David Taylor Model Basin's Series 64 models scaled to a 2500-ton displacement using the SHIPMO and MATLAB software. It also discusses the current technology associated with high speed vessels (HSV's) and the relation to the US Navy. Series 64 models provided the benchmark for resistance data. To expand upon this well known series, this research develops seakeeping data trends for scaled-up models. SHIPMO allows the user to specify the ship's characteristics and the environmental conditions such as wave specifications and spectrum. Using the output files from SHIPMO, the MATLAB program designed during this thesis, produced contour plots for the models' response in pitch and heave. Seakeeping trends were observed based on the plots and further compared to calculations of the seakeeping rank, R, a formula originally developed by Nathan Bales. The results of the research can be used by engineers in application to the design of small displacement, high speed ships, both monohulls and multi-hulls. / http://hdl.handle.net/10945/1070 / US Navy (USN) author.

In the present study, 3 wake parameters are semi-automatically measured in 63 composite-labeled images of a surface piercing propeller tested at yaw angles 0-30 degrees, pitch angles 0-15 degrees, propeller immersion ratios of 0.33 and 0.50 and scaled advance ratios 0.656-1.927. A fourth wake parameter is measured in four composite labeled images of yaw angles 0-30 degrees, pitch angle 0 degrees, immersion ratios of 0.33 and 0.50 and scaled advance ratios 1.363-1.927. Measurements are plotted against propeller's angular position. Major findings include the behavior of wake parameters as the values of scaled advance ratio, yaw angle, pitch angle, and immersion ratio vary. / by Luis Altamirano. / Thesis (M.S.C.S.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

Thesis. 1976. M.S.--Massachusetts Institute of Technology. Dept. of Ocean Engineering. / Microfiche copy available in Archives and Engineering. / Includes bibliographical references. / M.S.

In maritime vessels, it is desirable to minimise the structural and acoustic responses for several reasons, including passenger comfort, minimisation of crew fatigue, and in the case of military vessels, to avoid detection. The propeller-shafting system represents one of the most critical areas which must be addressed in order to reduce the low frequency acoustic signature. The propeller-shafting system is primarily excited by axial oscillations at the propeller. The force transmitted along the propeller-shafting system from these disturbances results in axial excitation of the hull and subsequent sound radiation. The aim of this thesis is to apply a combination of passive and active control techniques, in order to minimise the low frequency radiated noise signature of a pressure hull submerged in a fluid. Dynamic models of the propeller-shafting system, foundation and cylindrical hull including complicating factors such as fluid loading, bulkheads and onboard equipment are developed and described using the transmission matrix approach. This modular description enables greater flexibility for dynamic modelling of the propeller shafting system, and can be easily manipulated for future design modifications. The far-field radiated sound pressure from the submarine hull is evaluated and related to the force delivered to the hull by the propeller-shafting system. A passive optimisation scheme involving a genetic and general non-linear constrained algorithm is used to minimise fitness functions associated with the vibration of the propeller, vibration transmission to the hull and far-field radiated sound pressure over a low frequency range. This results in optimal resonance changer parameters for single and multiple resonance changers in a variety of configurations. A new quasi-adaptive resonance changer system is proposed and optimised to minimise the radiated sound pressure or propeller velocity. The optimal use of an adaptive resonance changer is investigated in both the frequency and time domains to reduce the hull velocity and subsequently the far-field radiated sound pressure. Fully active control is also evaluated by introducing a control force to the resonance changer with the aim of minimising either the propeller velocity or the radiated noise level. Finally, the concept of hybrid control is investigated by coupling passive, active and semi-active control techniques together to improve the overall performance.

The nonlinear response of an ocean system subjected to random excitations can exhibit very complex dynamic behaviors including jump phenomena and coexistence of attractors. In this study, the stochastic system response behavior of a simple (Duffing) oscillator under narrow-band random excitations is first examined in the subharmonic resonance region. A semi-analytical procedure based on the nonlinear response characteristics of the corresponding deterministic system is developed to derive the response transition probabilities within individual attraction domains and among finite attraction domains under the assumptions of stationarity and Markov process. Overall response amplitude probability distributions are obtained by applying the Bayes formula to the two different types of response transition probability distributions. To validate the prediction capability of the semi-analytical method, numerical simulation of the responses of the Duffing system are generated and statistical characteristics of the response behavior are compared with prediction results. It is shown that the semi-analytical procedure provides more accurate predictions than other approximate methods available in the literature. A parametric study on the effects of variations in excitation intensity and degree of narrow-bandedness is conducted. Results confirmed that the nonlinear response characteristics including jump phenomenon and co-existence of attraction domains are preserved under narrow-band random excitations. The semi-analytical prediction method developed above is then applied to analyze the stochastic response behavior of a nonlinear mooring system subjected to random ocean waves. For modeling of the structural system, a nonlinear�� structure, nonlinearly-damped (NSND) model is employed and a reverse multiple�� input/single-output technique is applied to identify the system coefficients. To verify the accuracy and capability of the semi-analytical method in predicting the complex behaviors of the nonlinear mooring system, analytical predictions are compared with experimental results and numerical simulations. System response amplitude probability distributions predicted by the semi-analytical procedure are shown to be in good agreement with experimental and simulation results. / Graduation date: 2001

Ancient ships of Japan, which are little known outside of Japan, are presented based on the studies of past researchers, as well as a comprehensive analysis of archaeological remains. The process of development from logboats to extended logboats or semibuilt-up ships, and finally to built-up ships is traced. This study covers evidence from the Early Jomon period (4000 - 3000 B.C.E.) through the Kofun period (300 - 700 C.E.). A large number of logboat remains date to the Jomon period, and it is these logboats which become the foundation of later Japanese ships. The number of ship remains from the Yayoi period diminishes. Therefore, iconographic evidence, mainly clay ship figures and drawings, are used in order to reconstruct the ships from that time. This thesis is an account of what is presently known about the ancient watercraft of Japan, based on the existing ethnographic literature, the archaeological record, and iconographic sources.