Water quality analyses in Grand Canyon examined Colorado River and tributary baseline water quality status in relation to recreational float trip use of the river corridor. Float trip use of Grand Canyon has increased over recent years (since 1966) to levels which have caused concern for water quality-river running associations. River runners have traditionally used the Colorado River and tributaries as sources of drinking and cooking water, for swimming and bathing, and, at times, as a disposal for some refuse, e.g., dishwater and leftover food. Associated with float trip use of the river corridor water resources has been potential water quality hazards. During the 1972 and 1979 float trip seasons (May through September) outbreaks of gastroenteritis occurred among river runners in Grand Canyon, prompting investigation by the Center for Disease Control, Atlanta, Georgia; an enteric pathogen Shigella sonnei was isolated from some river-trip participants. Potentially, the Colorado River or a tributary served as a source or carrier of the pathogen, though this has not been confirmed. Enteric disease organisms excreted in feces by humans, wildlife or domestic animals can become potential sources of infection; water contaminated with fecal organisms can distribute diseases. Water quality analyses of the Colorado River corridor occurred during the 1978 and 1979 river running seasons. Examination of the extensive river corridor necessitated analyses in the field. Travel through the Grand Canyon was via research rafts in a series of six float trips, April through September, in 1978, and two float trips, July and August, in 1979; 82 field days in 1978 and 22 field days in 1979. A total of 497 water quality samples were collected over two seasons from the Colorado River along the 225-mile stretch from Lees Ferry to Diamond Creek, the launch and take-out points of the research trips. The confluent reaches (within approximately 200 yards of the Colorado River) of 26 side creeks in the river corridor were also sampled in 1978; nine tributaries were sampled in 1979. Additional samples collected from upstream locations on some side creeks increased the tributary sample site total to 33 in 1978 and to 13 in 1979 for a two season total of 165 individual tributary samples. Selected microbial, physical, and chemical parameters were measured to determine baseline water quality status in the Colorado River corridor of Grand Canyon. Research emphasis was on microbial water quality; physical and chemical parameters were measured to facilitate evaluation of the microbial profiles. Microbial parameters included fecal coliform bacteria and fecal streptococcus bacteria densities; physical parameters included turbidity and water and air temperature; chemical determinations included alkalinity, hardness, phosphate, nitrate, chloride, total dissolved solids, and pH. Data from 1978 and 1979 show that the Colorado River and tributaries have similar bacterial water quality profiles. Surface waters show predominantly low FC densities, indicating high quality waters for recreational activities, based on established federal and state water quality standards. Treatment of river and tributary surface water is necessary to assure drinking water quality standards. Bottom sediment analyses modify considerably the water quality status represented by surface water analyses alone. Significant densities of enteric organisms are present in the river and tributary environments, representing an important water quality hazard. Associated with resuspension of bottom sediments is the probability of surface water contamination by enteric organisms. Recreational activities, particularly water play in confined tributary pools, can bring river runners in direct contact with concentrated sediment suspension in surface waters.

The Deployable Navigation System (DeNS) is a prototype system designed to facilitate Command and Control during over the horizon small boat operations. It is designed to allow small boats to deploy from their host ships with a Bluetooth GPS (Global Positioning System) receiver and PDA (Personal Digital Assistant) running the appropriate software which provides a real time navigational picture in terms of position and relation to a predetermined track. This same data is shipped immediately back to the control ship via a wireless network and displayed on a laptop computer to allow the mission commander to monitor the small boatâ s progress and position, also in real time. The small boatâ s relation to the track is compared on every received fix and appropriate indicators are displayed to inform both users if a predetermined distance from track (track tolerance) has been exceeded. It utilizes jpg formatted maps that are derived directly from the Digital Nautical Chart (DNC) library overlaid with track information. Positions received from the GPS are converted to pixel coordinates that correspond to their original positions on the jpg chart and plotted, providing an electronic display that is very similar in appearance to the traditional plot maintained on paper charts.

In this thesis multiple controllers are developed which command a small boat with twin tied outboard motors to hold a desired position. In the process of developing a controller to hold a position, controllers were first developed which follow a desired heading or path over ground with the motors outputting constant thrust. These heading and path following controllers were tuned and tested in a numerical simulation, then validated on the R/V Lee and Ocean Power vessels through sea trials in the Atlantic Ocean. After successful path following trials were performed, station keeping algorithms were developed and tuned in the numerical simulation, now with heading and thrust of the vessel both being variables to be controlled. After tuning in the numerical simulation, the Ocean power vessel was outfitted with systems for controlling throttle and steering with sea trials conducted in the Atlantic Ocean for station keeping. / by Aaron D. Fisher. / Thesis (M.S.C.S.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

The conceptualization of leisure constraints is dependent on negotiating a hierarchy of intrapersonal, interpersonal, and structural leisure constraints. It has become a recognizable and distinct subfield within leisure studies. Research has shown that the leisure constraints should not be necessarily viewed as insurmountable obstacles. Individuals can negotiate constraints by applying an array of coping mechanisms. Recently, Iwasaki and Schneider (2003) and Schneider and Stanis (2007) proposed that constraints negotiation and coping with stress share much in common. Leisure constraints are considered elements of stress, whereas constraint negotiation appears to share commonalities with ways of coping with stress. The distinction between negotiation and coping is that negotiation is something people have engaged in prior to participating in the activity, whereas coping involves strategies people more typically engage in during active participation (in response to unwanted or unanticipated situations). Based on past literature, I constructed a constraints-coping model to extend our understanding of constraints negotiation by integrating an understanding of coping mechanisms into leisure constraints-negotiation models. In order to broaden the scope of a constraints-coping framework, I integrated additional social indicators (e.g., commitment, motivation, place attachment, and frequency of participation) into my hypothesized model. First, my testing of the constraints-coping model provided empirical support for Iwasaki and his colleagues' suggestion that coping strategies can be potentially integrated into models of constraints-negotiation processes. Second, I confirmed that the three types of onsite constraints continue to have relevance for active participants. The three types of constraining factors directly influence subsequent aspects of leisure engagement for recreationists already participating. Third, I confirmed that recreationists are more likely to cope with constraints by employing an array of problem-focused coping strategies, rather than to simply adjust cognitively. However, my findings illustrate that recreationists' coping responses vary in response to different types of constraints encountered (e.g., intrapersonal, interpersonal, and structural). The experience of constraints did not universally result in the increased use of coping. Fourth, my results confirm that motivation is an immediate antecedent of constraints as well as a potential trigger for encouraging more problem-focused coping strategies. Last, four selected key variables (e.g., place attachment, commitment motivation, and frequency of participation) demonstrated different effects on influencing active participants' perceived constraints and subsequent coping strategies. Future investigations of coping strategies should continue to explore how active participants cope with onsite constraints based on a constraints-coping model in different settings.

Loggerhead sea turtles (Caretta caretta) can be found worldwide, inhabiting tropical and subtropical coastal waters. The loggerhead was classified as an endangered species and placed on the International Union for Conservation of Nature and Natural Resources (IUCN) Red List in 1996 (IUCN 2006).The problem of sea turtle mortality as a result of collisions with vessels is of increasing concern, especially in the southeastern United States, where increased development along the coasts results in increased recreational boat traffic. In the United States, the percentage of strandings that were attributed to vessel strikes has increased from approximately 10% in the 1980's to a record high of 20.5% in 2004 (NMFS 2007). This report presents results from field experiments designed to investigate the ways in which loggerhead sea turtles are injured in boat collisions, and the effectiveness of several mitigation options for reducing the risk of fatal interactions. In order to conduct these field experiments, a synthetic sea turtle carapace was designed and built that approximated the structural behavior of a biological sea turtle carapace. Hodges (2008) quantified the material strength properties of loggerhead sea turtle carapaces. From these results, it was determined that the target parameter for simulating tensile strength in a synthetic carapace should be force per unit width of sample. Hodges designed and constructed an artificial carapace made of composite material for use in controlled experiments. Modifications were made to the design proposed by Hodges (2008) to facilitate rapid construction. Several designs were tested using the force per unit width as the target strength parameter and compared to the strength of the biological carapace. Tests on the design ultimately adopted showed a force per unit width 17.6% stronger than the biological carapace. The composite material being stronger than the biological carapace means the testing will result in conservative reports of damage. Once the design and construction methods were finalized, approximately 60 artificial carapaces were fabricated for field testing. A frame, weighting scheme and buoyancy unit were designed and fabricated so that each test carapace floated at proper draft and had realistic specific gravity and weight. Field testing procedures were designed to investigate the influence of a) boat speed, b) animal position in the water column, and c) vessel propulsion system on the severity of vessel collisions on turtles. All experiments were done with small (<6 m in length) vessels. Boat/sea turtle collisions were simulated by placing a test specimen (a synthetic carapace attached to a test frame) in the water column and striking it with the vessel. The speeds considered were idle (7 km/h), sub-planing (14 km/h), and planing (40 km/hr). The two animal positions in the water column were 1) at the water surface and 2) at "prop depth" (depth to the center of the propeller hub on the standard outboard motor). Five propulsion options were tested: 1) a standard outboard motor, 2) a standard outboard motor with Hydroshield® propeller guard 3) a standard outboard motor with Prop Buddy® propeller guard, 4) a jet outboard motor and 5) a jet-propelled personal watercraft, often referred to generically as a "jet ski". The experiments typically included five trials per test configuration. Catastrophic (presumably fatal) damage was defined to occur when any damage penetrated the carapace. Small wounds (< 4 cm in length) along the sides or rear of the artificial carapace, where the shell and bone extend beyond the edge of the body cavity, were not classified as catastrophic This definition was used to classify the effectiveness of the various mitigation options. Results indicate that reducing the speed of the vessel reduces the odds of severe damage to the animals. Of all of the tests performed with the standard outboard motor (including tests with propeller guards installed), 25% of those performed at idle speed resulted in catastrophic damage, compared to 100% for planing speed tests. The two tested propeller guards both modified the type of damage to the animal when compared to similar tests with the standard motor configuration, but they only slightly reduced the risk of catastrophic damage. At idle speed, with propeller guard installed, 10% of the tests resulted in catastrophic damage. The corresponding number for the standard motor was 40%. At planing speed, 100% of the tests resulted in catastrophic damage, with or without the propeller guard. No catastrophic injuries were observed during testing of both jet propulsion systems (jet outboard and jet ski) at any speed or depth in the water column. Both feature a much smaller draft than the standard outboard, which results in little chance of striking an animal below the surface. And both the jet outboard and the jet-powered watercraft feature water intakes that are relatively smooth and appeared to slide across the animal with minimal damage to the carapace when the model animal was floating on the surface. The experiments described here involved a limited range of hull configurations; results may be different for hulls or propulsion systems drastically different than those tested here. But the results obtained indicate that equipment, in the form of the boat's propulsion system, and the mode in which it is used both play a role in defining the risk of boats to turtles in the field.

A simultaneous demand and supply model for the U.S. ski/wakeboard boat market is estimated by three-stage least squares and iterated three-stage least squares methods using publicly available data. The model is used to test if, and to what extent, certain factors impact the annual quantity of new ski/wakeboard boats demanded and supplied. Statistical analysis suggests that the model does a good job of explaining the annual quantity of new ski/wakeboard boats demanded and supplied. The findings are most immediately beneficial to manufacturers and dealers. Dealers can use the results to better forecast demand which in turn will lead to more efficient production planning for manufacturers.

Thesis (M.S.Env.E.)--University of Central Florida, 2009. / Adviser: C. David Cooper. Includes bibliographical references (p. 184-186).

Thesis (M. S.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Scott, David; Committee Member: Kurtis, Kimberly; Committee Member: Work, Paul. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (M.S.)--Oregon State University, 2011. / Printout. Includes bibliographical references (leaves 88-95). Also available on the World Wide Web.

Thesis (doctoral)--Uppsala universitet, 1982. / Extra t.p. with thesis statement inserted. Summary in English. Includes bibliographical references (p. 220-239).