Impact Of Boat Research Articles

Summer recreational boating impacts on erosion, turbidity, and phosphorus levels in Canadian freshwater lakes

Increases in boat traffic over time can present a risk to the integrity of aquatic ecosystems. In addition to severe environmental degradation or boat-related disturbances, boat wave’s kinetic energy can induce a cumulative impact on freshwater ecosystems. However, seldom data report the impacts of boat waves on shoreline erosion and physico-chemical properties on freshwater lakes. In this study, we monitored shoreline erosion, turbidity, and total phosphorus levels. Wave-induced shoreline erosion was measured through shoreline rebar pin excavation across five lakes in southern Quebec. Sediment resuspension was measured through turbidity sampling in Lake Massawippi over three years. Total phosphorus was also monitored for potential impacts of sediment resuspension. Our study did not detect significant shoreline erosion. However, water turbidity was positively correlated with boat traffic and wind speed and negatively with the littoral slope angle. Moreover, water total phosphorus levels were positively correlated with turbidity. Thus, despite a lack of detectible impact on the shoreline, our results suggest that boat waves can have an impact on freshwater lakes with an increase in sediment resuspension and phosphorus availability. Management agencies could therefore benefit in the long-term from implementing or reinforcing policies aiming to minimize the impact of boats on sediment resuspension.

An Approaching Motor Boat Induces Stress-Related Behaviors in Proboscis Monkeys (Nasalis larvatus) Living in a Riparian Area

Primate ecotourism is a fast-growing tourism sector that may have a negative effect on wildlife. In riparian areas, tourists can conveniently reach primates via motor boats, but no study has directly examined whether such boats cause stress in primates. Our goal was to test whether the approach of a motor boat induces stress-related and other behaviors in proboscis monkeys (Nasalis larvatus), an Endangered species. We studied six one-male, multifemale groups living in a remote riparian area in Sabah, Malaysia, and conducted an experiment by approaching the monkeys in a motor boat by using three conditions with different speeds and travel distances (fast-close, slow-close, and slow-far conditions; 7-8 subjects per condition). For each condition, we compared stress-related behaviors before the boat approach with after the boat started approaching. Feeding, allogrooming and aggression were similarly examined, respectively. We also observed the monkeys’ behaviors at other times to examine age-sex classes differences in vigilance, social proximity, allogrooming, aggression and play (87 subjects). In the experiment, subjects displayed stress-related behaviors for longer in the fast-close and slow-close conditions once the boat started approaching than before the boat approach. The subjects also reduced feeding in the fast-close condition after the boat started approaching. In our observational study, males were more vigilant than females—a behavior that is likely to relate to male-male competition and group protection. This study provides evidence that even a single motor boat moving slowly, with humans behaving calmly, may negatively affect primate behavior and induce stress—an impact that is likely to be larger with tourist boats. Our study also shows that using conditions comparable to the slow-far condition (speed of 3.6 km/hr; no closer than 60 m), where no impact was observed, may help with to develop guidelines for primate tourism in riparian areas. Future research that examines the impact of boats on other primates is needed.

On the Problem of Modeling the Boat Wake Climate: The Florida Intracoastal Waterway

AbstractQuantifying and forecasting the impact of boat traffic on the health of coastal ecosystems must account for the multiscale nature of the process: from minutes (individual wakes), to days (tidal phase), weeks, and longer (tide modulation, seasonal traffic). Direct numerical simulations covering all these scales are difficult, not in the least because specifying the vessel type and navigation characteristics for every wake is practically impossible. To overcome this problem, we propose a statistical‐mechanics description of the wake field that focuses on classes of wakes, defined by a set of characteristic parameters, and their joint probability density in the characteristic‐parameter space. Here, we demonstrate the first steps of the approach using existing numerical tools and parametrizations. Because vessel type and navigation characteristics are not available, an investigation of wake parameter space is not possible at this time. Instead, we use the leading‐order Froude‐number parametrization defined by a linear model to classify the wake population observed during the field experiment. Numerical tests applying the FUNWAVE‐TVD model across all wake‐classes identified show excellent skills for weakly dispersive wakes. The model is challenged by the short waves generated by small, slow boats. However, simulations suggest that the problem is confined to the deeper water domain and linear evolution. Nonlinear wake shoaling, essential for modeling wake‐induced sediment transport and wake impact on the environment, is described well.

A Novel Boat Shock Vibration Control using Momentum Exchange Principle with Pre-Straining Spring Mechanism

This research proposes a new method for boat impact vibration attenuation using the exchange of momentum principle with a pre-straining spring mechanism. The boat dynamic is modeled using a hinged-supported beam structure. The wave excitation on the boat hull is expressed using one degree of freedom spring-mass system. The simulation study is performed to evaluate the impact damper performance in reducing the boat shock response. Two kinds of momentum exchange impact damper i.e., without and with pre-straining spring mechanism, are evaluated. The simulation results show that the impact damper with pre-straining spring mechanism (PSMEID) is better than the passive momentum exchange impact damper (PMEID) in reducing the boat shock vibration response

Missing the Boat–Impact of Just Missing Identification as a High-Performing School

ABSTRACTThis study capitalizes on the performance identification system under the No Child Left Behind waivers to estimate the school-level impact of just missing formal state recognition as a high-performing school. Using a fuzzy regression-discontinuity design and data from the early years of waiver implementation in Rhode Island, we find that, when schools that just missed achieving status as a high-performing school (i.e., leading) were located in districts with a large proportion of schools achieving this status, they performed better in subsequent years. Alternatively, when similar schools were in districts with few leading schools, we find no effects.

Identification of support structure damping of a full scale offshore wind turbine in normal operation

The support structure damping of a 3.6 MW pitch controlled variable speed offshore wind turbine on a monopile foundation is estimated both in standstill conditions and in normal operation. The net substructure damping is identified from the parameters of an exponential curve fitted to the relative maxima of an impulse response caused by a boat impact. The result is used in the verification of the non aerodynamic damping in normal operation for low wind speeds. The auto-correlation function technique for damping estimation of a structure under ambient excitation was validated against the identified damping from the decaying time series. The Enhanced Frequency Domain Decomposition (EFDD) method was applied to the wind turbine response under ambient excitation, for estimation of the damping in normal operation. The aero-servo-hydro-elastic tool HAWC2 is validated with offshore foundation load measurements. The model was tuned to the damping values obtained from the boat impact to match the measured loads. Wind turbulence intensity and wave characteristics used in the simulations are based on site measurements. A flexible soil model is included in the analysis. The importance of the correctly simulated damping in the model is stressed for accurate load prediction. Differences in the identified damping between the model and the wind turbine are detailed and explained. Discrepancies between simulated and measured loads are discussed.

Disturbance to a foraging seabird by sea-based tourism: Implications for reserve management in marine protected areas

The provision of recreational opportunities is one of the important human goals of marine protected areas. However, as levels of recreational use increase, human disturbance is likely to cause significant detrimental effects upon wildlife. Here we evaluate the best managing options to mitigate the impact of sea-based tourism on the foraging activity of an endangered population of European shags, Phalacrocorax aristotelis, in a coastal marine protected area (Cíes islands, north-western Iberia). Boat disturbance elicited a characteristic avoidance behavior that resulted in a substantial reduction in foraging activity as levels of boat use increased. Moreover, boats excluded shags from the best feeding areas, resulting in higher densities of foragers in areas of little boat traffic. We used a behavioral model to explore the effects of managing strategies aimed at reducing the impact of boats on the foraging activity of shags. Our model suggested that in low boat disturbance scenarios limiting the number of boats using the reserve would be a better management option than habitat protection (i.e. the establishment of set-aside areas free of boat traffic). On the contrary, when boat disturbance levels are high the protection of habitat is recommendable, even if spatial variation in habitat quality is unknown or poorly assessed. Our study stresses the point that management strategies to minimize disturbance to foraging seabirds may depend on the spatial overlap between sea-based recreational activities and foraging seabirds and the spatial variation in marine habitat quality for seabirds.

Safety factor requirements for the offshore industry

The maintenance of structural integrity is a significant consideration in the safety management of offshore installations. Installations operating in the North Sea are primarily of welded construction and are subjected to severe environmental conditions, which induce significant fatigue loads. Thus, offshore installations are designed to resist structural failure from fatigue and extreme loading as well as other failure mechanisms, e.g., corrosion. Additionally, design to resist failure from accidental loading, such as fire and explosion and boat impact, is recognised as being particularly important. The need to maintain safety standards is of particular relevance on the United Kingdom continental shelf (UKCS) where there is an increasing ageing population of installations which have exceeded their original design lives and which subsequently require reassessment to ensure that structural integrity is maintained through the life cycle. The emphasis on safety highlights the need for appropriate structural integrity assessment procedures and the use of appropriate safety factors. A particularly important development has been the major international effort since 1993 to produce an ISO standard for offshore structures. This has entailed the harmonisation of relevant national codes and standards and the development of new procedures where appropriate, resulting in the derivation of revised safety factors for offshore structures. The subject of safety factors within the ISO arena and in terms of the general requirements for offshore structures is addressed in this paper.

Response of dugongs to boat traffic: The risk of disturbance and displacement

Disturbance from boats has been documented for many species of marine mammals, especially cetaceans, but has never been quantified for dugongs. Dugongs depend on seagrass for food. This food mostly occurs in shallow coastal areas where boat traffic is high. Thus there is potential for boats to alienate dugongs from critical habitat areas. Using an overhead video observation system (‘blimp-cam’), we observed the behaviour of focal dugongs during controlled boat pass experiments and while no boats were present. The percentage of time focal dugongs spent feeding and travelling was unaffected by boat presence, the number of boat passes and whether a pass included a stop and restart (pass continuity). The duration, distance and direction of a focal dugong's subsurface behaviour were unaffected by number, continuity or distance of boat passes. However, focal dugongs were less likely to continue feeding if the boat passed within 50 m, than if the boat passed at a greater distance. Mass movements of dugong feeding herds in response to experimental and opportunistically observed boats were timed on 42 occasions but only lasted an average of 122 s. These movements occurred in response to boats passing at a range of speeds, and at distances of less than 50 m to over 500 m. The levels of boat traffic we observed may reduce dugongs' feeding time budget by a maximum of 0.8–6%. Thus at present boats appear unlikely to be having a substantive effect on the energy intake of dugong populations at our study site on the Moreton Banks near Brisbane, Australia. However, boat traffic is likely to increase in this fast growing region, raising concern about the future impact of boats on this and other dugong populations.

Impact of boats on the vocal behavior of humpback whales off Brazil

Experiments were performed to evaluate the impact of boat approaches on the vocal behavior of humpback whales that breed around the Abrolhos archipelago off the Brazilian coast. Vocalizing whales were located by monitoring the amplitude of each individual’s sounds. Silent approaches to focal singers were performed using a small zodiac with an improvised sail. Songs were recorded with one hydrophone connected to a portable DAT recorder before and during the approach of a vessel. Spectrograms were correlated to each whale’s activity and position with respect to the vessel. Differences in song variables of two individuals were tested when the motor was ON and OFF. Both whales sang shorter versions of their songs when exposed to engine noise. No alteration in mean phrase duration was detected, but the number of phrases in each theme decreased. Three individuals interrupted their songs after a motor boat switched gears within 300 m, and resumed singing when the engine was returned to neutral. The limited number of observables calls for further investigation to evaluate the consequences of boat impact. More reliable information will allow regulation to achieve sustainable tourism activity in the area. [Work supported by FBPN, MacArthur Foundation, Society for Marine Mammalogy, Instituto Baleia Jubarte.]

Assessment of jack-up boat impact analysis methodology

In 1991 the Health and Safety Executive (HSE) commissioned a study to review the resistance of jack-ups to boat impact. A resulting conclusion was that jack-ups offer only limited resistance to severe damage in such events. Subsequent safety case assessment in the period 1993–1995 highlighted a significant range in the predicted impact resistance of jack-ups, which assessors believe to be more dependent on the approach followed rather than on the basic design. As a result further work was considered necessary to identify key factors that duty holders should be considering as part of the analysis undertaken to demonstrate the case for safety. This paper has been produced in order to disseminate the findings of such a study carried out on behalf of the HSE. The study carried out by Det Norske Veritas (DNV) presents the results of the appropriateness and applicability of a range of typical methodologies used by the offshore industry to analyse the response and impact resistance of jack-up designs to boat impact. The collision between offshore platforms and boats is generally a very complex problem and it is often not practical to perform rigorous finite element analyses to include all effects and sequences during the collision. A significant part of the collision energy is dissipated as strain energy and except for global deformation modes, the contribution from elastic straining can normally be neglected. Hence, many times it is necessary to apply simplified techniques. However, key aspects such as dynamic effects are often ignored, sometimes to the detriment of the final calculated energy absorption capacity of the jack-up. A number of approaches were received and identified by the HSE as typical approaches for design justification of Jack-Ups in the North Sea within safety case submissions. In order to assess and compare the approaches a case study based on a typical jack-up design with three legs was used, each leg consisting of triangular sections and K-bracing. Impact resistance calculations were performed, ranging from simple elastic hand calculations to non-linear dynamic FE analyses. In one approach where an assessment by calculation would have proved too time consuming, a qualitative assessment has been carried out instead. The results of the assessments based on the different approaches are presented, compared and discussed in this paper.

PENANG BRIDGE PROJECT: SUPERSTRUCTURE - DESIGN AND CONSTRUCTION.

Keywords HOWARD NEEDLES TAMMEN & BERGENDOFF., JURUTERA KONSULTANT HYUNDAI BRIDGES, PENANG BRIDGE, DESIGN, SPANS, LOADS, DECKS, RUBBER, AERODYNAMICS, TESTS, ANCHORAGES, COUNTRIES, PROJECTS, CONSTRUCTION, NAVIGATION, SEISMIC, PIERS, BEARINGS, STAYS, STATIC, TENDERS, DEVELOPING, SUPERSTRUCTURES, CABLE STAYED, CHANNELS, SEISMICITY, NATURAL, LAYOUT, CABLES, DYNAMICS, TROPICS PENANG MALAYSIA, ASIA... Show All