Thesis. 1978. M.Arch.A.S.--Massachusetts Institute of Technology. Dept. of Architecture. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH. / Includes bibliographical references. / by Peter Droege. / M.Arch.A.S.

My result address the problem that getting back up in the boat after one have fallen in can be very difficult. My research led me to focus on the very smallest boats, rowing boats and open motorboats under 6 meters in length. My solution to the problem is to provide an easily attached footstep that can be reached and pulled down from water level. The product can be adapted to different boats. For the smallest boats, manually activated flotation units can be integrated to prevent the boat from tipping.

Two-stroke outboard boat engines using total loss lubrication deposit a significant proportion of their lubricant and fuel directly into the water environment. Extensive atmospheric emission testing of outboard motors has taken place, however, emissions to the water are largely unaddressed in the literature and could be critical because the exhaust of most outboard engines is released below the water and mixed by the action of the propeller. The purpose of this work is to document the velocity and scalar field characteristics of a submerged swirling jet emanating from a propeller. The aim is to provide guidance on fundamental characteristics of such a jet, far enough downstream that it is relevant to the eventual modelling of this mixing problem (i.e. the mixing of engine emissions with water). Measurements of the velocity field (axial, tangential, and radial) and scalar field (concentration) were performed in a turbulent jet generated by a model boat propeller (0.02 m diameter) operating in a weak co-flow of 0.04 ms-1. The measurements were carried out up to 50 propeller diameters downstream of the source which was placed in a glass-walled flume, 0.4 m wide with a free surface depth of 0.15 m. The jet and scalar plume development were compared to that of a classical free round jet. Further, results with respect to velocity distribution, turbulence decay and integral flow properties plus scalar distribution, dilution and integral plume properties were all calculated and compared to existing literature. The velocity field results are the first published results to show the development of the flow fifty propeller diameters downstream. Up to ten propeller diameters downstream the results corroborate the earlier work of Petersson [1, 2]. Beyond ten propeller diameters downstream, the walls of the flume affected the flow. The concentration field results show that under these experimental conditions the propeller induced mixing exhibited a complete mixing length some 300 times shorter than for the wall-shear induced diffusion alone. Furthermore, a first principles relation was derived that illustrates the link between engine emission rate and propeller kinematics in generating the propeller-jet source concentration of pollutants. Using experimental results an estimate for benzene concentration fifty propeller diameters downstream of a 74 kW vessel was calculated to be around one third of the regulatory threshold for that chemical.

No description available.

Fully-electric powerboats are few and far between and have yet to capture any significant market share away from traditional gasoline powered boats. However, with advances over the last 5-10 years in battery technology, an electric boat is not just a possibility, but an attractive one. By combining Tesla’s innovative battery and motor technology with thorough analysis of every component of a boat’s design—hull form, interior and exterior aesthetics, performance, comfort, efficiency, materials, and function—a fully-electric, high-performance motor boat is clearly realistic. Depending on a variety of variables, this hydrofoiling catamaran with quad-motors and batteries can overcome hydrodynamic and aerodynamic resistance to reach max speeds over 50mph and a potential range of 200-300 miles all while maintaining a high, but luxuriously comparable cost of $100,000-$400,000.

In recent years, intertidal reefs of Crassostrea virginica (eastern oyster) along central Florida's east coast have suffered extensive losses due to wakes from recreational boats. These wakes have caused extensive shell movement and sediment resuspension which results in large piles of disarticulated shells along the seaward edges of reefs. Dead margins extend up to one meter above mean high water. The creation and enforcement of "no wake" zones in the area are unlikely. Thus, there is an urgent need for an alternative restoration strategy before these oyster reefs decline any further. The goal of this project was to develop a scientifically-based restoration technique that minimized wake damage from recreational vessels on intertidal reefs in Canaveral National Seashore. To accomplish this, I tested a range of restoration measures to identify a design that best increased: 1) oyster recruitment, 2) three-dimensional structure of the intertidal reefs, and 3) biodiversity and abundances of sessile and motile species associated with reefs. As a starting substrate in all treatments, I used restoration mats, which were created by affixing 36 drilled oyster shells to 0.4 x 0.4 m pieces of black mesh (Vexar). Five mats were deployed on the fore-reef, midreef, and backreef areas of each reef. In my experiment, I manipulated two habitat conditions: 1) leveling of existing dead margins to bring the top of the dead margin below mean high water to facilitate settling of larvae, and 2) deploying artificial seagrass seaward of the mats to act as a wake buffer. All combinations of these variables and all appropriate controls were replicated on six oyster reefs each, for a total of thirty reefs. Reefs that were leveled were significantly reduced in height and this difference was maintained throughout the 1 year study. Unleveled reefs actually increased in mean height over the 12 months. Tracking loose shells covering our restoration mats over time likewise documented that shell movement was minimal on control reefs lacking dead margins and significantly greater on reefs with dead margins. Midreef areas on reefs with dead margins were almost completely buried by loose shells. Quarterly monitoring of the number of spat settling on all restoration mats allowed for comparisons between treatments and locations on oyster reefs. After determining that overall water flow on the fore reef areas of all treatments was similar, I tested the null hypothesis that all treatments had similar recruitment of oyster larvae. My first alternative hypothesis was that artificial seagrass would increase oyster recruitment if the grass was a successful wake buffer and minimized sediment resuspension known to be lethal to newly settled oyster or prevented disarticulated oyster shell from moving and reforming mounds. My second alternative hypothesis was that the leveling of the dead margins would increase the total reef surface area available to larval oyster recruitment and thus lead to an increase in the number of recruits and eventually 3-dimensional reef structures (when oysters grow in close proximity and affix themselves together). Statistical analyses showed the artificial seagrass did not decrease the negative impacts caused by recreational boat wakes. Hence, it is not a recommended method for reef restoration. Recruitment of oysters significantly increased over time and significantly differed on various regions of the reefs. Recruitment was always highest on the fore-reef regions and lowest on back-reef regions. Although overall recruitment did not differ among treatments, it was significantly lower on midreef regions of the impacted reefs. This suggests that the leveling of the oyster reefs would increase the surface area available for future oyster recruitment. To look at biodiversity, I tested the hypothesis that all treatments would have similar biodiversity on a month by month basis. Alternatively, biodiversity should always be greatest on leveled reef with artificial seagrass due to increased 3-dimensional structure nearby and longer submersion times. To enumerate biodiversity, two lift nets were placed on each reef, one contained a restoration mat and the other contained only mesh (control). In most months, the four experimental treatments were similar according to the biodiversity measures analyzed. However, biodiversity was always higher in lift nets with restoration mats when compared to lift nets with mesh only. This result again suggests that the mats as designed are important restoration tools. Overall, my results show that placing seagrass in front of oyster reefs may not help to better restoration efforts. However, leveling dead margins on reefs and using the restoration mats is beneficial to oyster reef habitat restoration efforts. As a result of my research, restoration mats, in combination with leveling dead margins, are currently being used in a large-scale, community-based oyster reef restoration project within Canaveral National Seashore boundaries.

Det har uppmärksammat att det fortfarande förekommer tenn och koppar från båtbottenfärg på fritidsbåtars skrov trots förbud av båtbottenfärger med tennföreningen TBT sedan 1989 och reglering av kopparbaserade färger sedan 1999.Syftet med denna kandidatuppsats är att ge en dagslägesrapport vad gäller förekomst av tenn och koppar på fritidsbåtars skrov.Under våren 2011 har tester på 336 fritidsbåtar i tre vattenområden gjorts med hjälp av en handhållen XRF (X-Ray Fluorescence, röntgenfluorescens) som genom avläsning av en yta visar halter av olika grundämnen. Testerna utfördes på vinterförvarade fritidsbåtar <12 m hos båtklubbar vid Mälaren, Storsjön och Härnösandskusten. Undersökningen visar att 73 % av båtarna i denna undersökning har halter av tenn och/eller koppar överstigande >2500 ppm, vilket är det för rapporten satta riktvärdet. Det innebär att de skulle kunna tas vidare till kemisk testning med till exempel gaskromatografi kopplad till masspektrometri (GC-MS) för att avgöra exakt vilken substans färgen innehåller. Resultatet visar också att användningen av tennfärger antingen fortfarande förekommer i liten skala eller att gamla tennfärger är så pass starka att de ger utslag genom övermålade färglager. Kopparfärg verkar användas både vid ostkusten och i insjöar.Antifoulingsystem som kan ersätta bottenfärg blir allt vanligare och det dyker upp fler och fler mer miljövänliga alternativ på marknaden. Det vanligaste alternativa systemet, båttvättar, blir dock mindre miljövänligt i och med förekomst av gammal färg innehållande skadliga substanser som tvättas av i båtborsttvättar med starkt bristfällig uppsamling och rening av avfallet/slammet. / It has been noticed that tin and copper are still present in antifouling paints residing on the hulls of leisure boats, in spite of a ban of TBT-based paints since 1989 and strict regulations regarding copper-based paints since 1999.This bachelor thesis aims to give the reader a view of the current situation regarding the presence of tin and copper on the hull of leisure boats.During the spring of 2011, 336 leisure boats in three different waters were tested with a hand-held XRF analyzer (X-Ray Fluorescence). After scanning the surface of a hull the machine displays the paint’s proportions of basic elements. Testing was performed on leisure boats, winter-stored at yacht clubs connected to the lakes Mälaren, Storsjön and the coast of Härnösand. In this study 73 % of the tested boats show levels of tin and/or copper exceeding the (for this essay) set limits of 2500 parts per million, which means they could qualify for further testing, gas chromatography coupled to mass spectrometry (GC-MS) for example, to determine the exact substances in the paints. The results also show that tin-based paints are either still in use, albeit in small scale, or that they are strong enough to detect through another layer(s) of paint. Copper-based paints seem to be used both along the east coast and in fresh-water lakes.More and more alternative antifouling systems that are capable of replacing paints while being more environmentally friendly are reaching the market. The most common alternative, to wash the boat with brushes or with a high-pressure water jet, is somewhat less environmentally friendly when the boat is painted with harmful substances and the facilities lack proper collection and sanitation of the wastewater.

The Viking Age cemetery of Tuna in Alsike from the 9th - 11th century AD is located in the eastern part of middle Sweden and contains inhumation boat graves. Here analysis of Strontium isotopes, using laser ablation method on the tooth enamel of the canine and first molar of two individuals buried in boat-graves XI and XIII have been performed. Comparing Strontium isotope evidence with local strontium ratios and variations indicated that at least one individual, the one in boat-grave XIII, were non-local.

No description available.

To be an island, Taiwan owns an abundant ocean environment, therefore, it is good to develop varied marine activities. Keel-boat is one of the important activities just budding from the branch. Our study explored the development of keel-boat activity in Taiwan, following with an analysis framework of four-function development, i.e., leisure, sports, education, and industry. Methods of case study and qualitative skills, such as interviews, documentary analysis, and observation were used in this study, including applying on varied actors, i.e., governmental units, NGOs, business, and individuals. Data was analyzed under the four-function framework and some results had been produced as the following: 1. Leisure and sports are dominant functions of keel-boat activity in the post development. However, leisure should be the future developing direction. 2. The actors in private sector play an important role to promote keel-boat leisure. 3. Some regulations needed to be changed for the development of keel-boat activity.