Combustion engines and fossil fuels have traditionally driven motor-powered leisure boats. Electrification is quickly transforming the transportation sector, but electric boats are rare. The primary drawback of the electric boat is the high production cost. This study explores the existing leisure boat manufacturers’ efforts and attitudes toward leisure boat electrification. The study is primarily qualitative and uses semi-structured interviews as the dominant data-gathering method. A theoretical framework that covers industrial transformation and innovation was used to analyse the data. This analysis was divided into socio-oriented and firm-oriented features. Enablers and barriers were identified, and a cycle of electric boat development was developed. Enablers identified are the altered nature experience, lower running costs, legislative incentives, less need for maintenance, upcoming scientific progressions and new business opportunities. Barriers identified are cultural concerns, knowledge gaps, infrastructure hesitations, demand awaiting, and disbelief of regulations significance. Manufacturers mostly perceive the socio-cultural experience as the essence of leisure boating. Traditionally manufacturers map the market demand by user surveys and put small efforts into influencing the market. Manufacturers generally believe that environmental concerns are the primary motive for the sales of electric boats. The electric boat development cycle is a model that explains the society-firm dynamics of the leisure boat market. The characteristics of the electric boat are distinct yet subjective, much like the leisure boat culture. If the socio-culture of leisure boats could be redefined, the electric transition could be accelerated. / Motordrivna fritidsbåtar har traditionellt drivits av förbränningsmotorer och fossila bränslen. Elektrifiering förändrar snabbt transportsektorn, dock är elektriska båtar fortfarande sällsynt. Elbåtens främsta nackdel är den höga produktionskostnaden. Denna studie utforskar befintliga båttillverkares arbete samt inställning till elektriska fritidsbåtar. Studien är primärt kvalitativ med semi-strukturerade intervjuer som datainsamlingsmetod. Ett teoretiskt ramverk täckande innovation och socio-teknisk transformation användes för att analysera insamlad data. Analysen är uppdelad i socio-orienterade och tillverkar-orienterade faktorer. Drivkrafter samt hinder till elektriska fritidsbåtar identifierades och en cykel för utveckling av elektriska båtar togs fram. Drivkrafter som identifierats är den förändrade naturupplevelsen, lägre driftskostnader, mindre underhållningsbehov, lagstiftningsincitament, vetenskapliga framsteg samt affärsmöjligheter. Hinder som identifierats är kulturella frågetecken, kunskapsbrist, väntan på efterfrågan, infrastruktur och skepticism kring lagstiftnings significans. Bland båttillverkare uppfattas den socio-kulturella upplevelsen som det viktigaste för fritidsbåtar. Traditionella båttillverkare tenderar att kartlägga efterfrågan genom användarundersökningar och lägger inte resurser på att påverka marknaden. Båttillverkare antar vanligtvis att miljöhänsyn i sig är den främsta drivkraften för köp av elbåtar. Utvecklingscykeln för elbåtar är en modell som förklarar dynamiken mellan samhället och tillverkare av fritidsbåtar. Elektriska fritidsbåtars egenskaper är distinkta men samtidigt subjektiva vilket liknar båtkulturs karaktärsdrag. Ifall båtkultur kan omdefineras skulle det möjligen kunna påskynda det elektriska skiftet.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2006. / The main objective of this thesis was to design a hydrofoil system without a trim and ride height control system and investigate the change in resistance of a representative hull across a typical speed range as a result of the addition of the hydrofoil system, while retaining adequate stability. The secondary objectives were as follows: Find a representative hull of sailing catamarans produced in South Africa, and to establish an appropriate speed range for that hull across which it is to be tested. Test and explain the drag characteristics of this hull. Find a suitable configuration of lifting foils for this hull that would not require any form of trim or ride height control to maintain stability throughout the speed range. Test and compare the resistance characteristics with and without the assistance of lifting foils. Test and explain the effects of leeway and heel on the total hydrodynamic resistance both with and without lifting foils. A representative hull (RH1), based on a statistical analysis of sailing catamarans produced in South Africa and an existing hull design of suitable size, was designed. A speed range was then established (0 – 25 knots) based on the statistics of the original (existing) design. A scaled model (of RH1) of practical and suitable dimensions was designed and manufactured, and its characteristics determined through towing tank testing. A hydrofoil system was then designed and during testing, was adjusted until a stable configuration was found. This resulted in a canard type configuration, with the front foil at the bow and the main foil between the daggerboards. Although a stable configuration was achieved, it was noted that any significant perturbation in the trim of the boat would result in instability and some form of trim control is recommended. The main objective was achieved. The experimental results concluded that a canard configuration was found to be stable for the RH1 (foil positioning already mentioned) and the addition of the hydrofoils provided a significant improvement only above a displacement Froude number of 2, which for our full scale prototype, is equivalent to approximately 14.2 knots. This is in agreement with the results of several other research projects that investigated hydrofoil supported catamarans with semi‐displacement type demi‐hulls. Below displacement Froude number of 2, a significant increase in total hydrodynamic resistance was observed. Since the speed of sailing craft is dependent on wind speed, there will often be conditions of relatively low boat speed (below displacement Froude number of 2). So it was recommended that a prototype design would have a retractable hydrofoil system which could be engaged in suitable conditions (sufficient boat speed). The effects of leeway and heel on the total hydrodynamic resistance were determined experimentally, but it was found that these trends were affected by the resulting changes in wave interference resistance. Since wave interference depended strongly on the hull shape, it was therefore concluded that no universal trends can be determined regarding the effects of heel and leeway on the total hydrodynamic resistance. These effects were determined for RH1 and it was shown that these effects are drastically altered by the addition of the lifting foils.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2005. / This work is concerned with the design and hydrodynamic aspects of a hydrofoil-assisted trimaran. A design and configuration of a trimaran is evaluated and the performance of a hydrofoil-assisted trimaran is effectively compared to the performance of a hydrofoil-assisted catamaran with similar overall displacement and same speed. The performance of the trimaran with different outrigger clearances are also evaluated and compared. The hydrodynamic aspects focuses mainly on the performance and to a lesser extend on the sea-keeping and stability of a hydrofoil-assisted trimaran. The results were determined by means of experimental testing, theoretical analysis and numerical analysis. The project was initiated as a result of the success of the hydrofoil-assisted catamarans and due to the fact that there does not exist a hydrofoil-assisted trimaran (to the author’s knowledge) where the main focus of the foils is to significantly reduce the resistance. A brief history, recent developments and associated advantages regarding trimarans are discussed. A complete theoretical model is presented to evaluate the lift and drag of the hydrofoils, as well as, the resistance of the trimaran. The data so obtained is then used to compare the reliability and feasibility of the numerical and experimental predicted values. The design of the trimaran and hydrofoil system is explained, together with the problems associated with the final design of the trimaran. The design of a trimaran is much more complicated than a catamaran due to more design variables being associated with trimarans. The selection of the trimaran configuration is done in a logical manner considering stability and hydrodynamics. However, the hydrofoil-assisted trimaran is closely adapted to the main dimensions of the comparable hydrofoil-assisted catamaran. An in-depth discussion of the testing technique used and the problems that are associated with towing tank testing will facilitate similar tests in the future. The scaling method of Froude was modified to account for the different sized hulls. The numerical methods are explained, with emphasis on accuracy, limitations, feasibility and the time required to complete a calculation. The results are presented in an order suggested by the experimental and numerical work carried out. The resistance, trim and rise/sinkage results are presented with speed for both the trimaran and catamaran with and without the addition of foils. The addition of the foils supplies results based on the amount of lift the foils carry and therefore can easily clarify the significant resistance advantage the foils offer the trimaran and the catamaran evaluated in this project. The final design and results of the evaluated trimaran are discussed. It is concluded that the catamaran with similar displacement and speed is still superior to the trimaran, with and without foils in both cases. The addition of foils to the trimaran does decrease the resistance significantly. The conclusions regarding these results are presented, together with recommendations for future work.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2007. / The successful use of hydrofoil systems on catamarans, such as the Hysucat, led to the development of a similar foil system for a high speed trimaran. Firstly a mathematical model was developed to calculate the equilibrium planing conditions of a planing trimaran. This was then used in the hydrodynamic design of a fully planing trimaran with a design speed of 65 kn. The mathematical model was then modified to include the effects of added hydrofoils. This model was then used to design a hydrofoil support system for the planing trimaran. Towing tank tests were then performed on a scale model of the boat, with and without the supporting hydrofoil system. This was done to verify the theoretical design and to gather resistance data, which could then be compared to other boats. The results showed a notable improvement in efficiency of the boat with the addition of foils. The conclusion was made that with the addition of a well-designed foil system, hull efficiencies similar to that expected for the Hysucat, can be attained when the foil system is added to the trimaran. As this work was focused mainly on the high-speed performance of the boat, it is not certain how the boat will perform through the speed-range. It is therefore recommended that further testing be done, to determine the performance of the boat at lower speeds.

Thesis (MBA)--Stellenbosch University, 1984. / BACKGROUND AND OBJECTIVE: The chief sector of the South African fishing industry, demersal trawling is in a state of uncertainty that brings its competitiveness and long term developnent into question. The Hake (Merluccius capensis and Merluccius paradoxus) resource, which accounts for 70% of the landed catch, has finally started on the expected road to recovery and it is anticipated that this will proceed shortly for a nunber of years. During 1983 comfort was derived from the resulting rise in catch per unit effort rates and a significant improvement in the average size of fish landed. This, together with lower fuel prices and increased operating efficiences, enable the industry to operate at lower expenditure. Unfortunately, a second successive reflection of the T.A.C. (Total Allowable Catch ) of 12% in 1983 meant that gains in productivity were not fully reflected in reduced landed costs. This year (1984) the T. A. C. was increased by 4,8% which only marginally improves the already poor situation. More serious difficulties can be traced to adverse market developments. The price of fish has fallen in real terms (see Table 1.1 below) over a number of years. However, in 1983, the industry experienced a startling fall in prices, the severity of which may be gauged from the fact that actual prices realised were roughly equal to those of 1981. (Bross, 8 May, 1984) This pattern is continuing through 1984 - as is seen in Table 1 .1, an extract from Irvin & Johnson financial results .

Uppsatsen undersöker orsaker till fenomenet girting, dvs olyckor där bogserbåtar dras ned och potentiellt kapsejsar vid bogsering av farkoster. Undersökningen utgår från 14 officiella haverirapporter om girtingsituationer världen över.  Med hjälp av modellen HFACS-MA kategoriseras olycksorsakerna i en orsakskedja för att utröna vilka kategorier som är mest frekvent förekommande i samtliga undersökta olyckor. Resultatet visar att dåligt förberedda bogseroperationer (med otillräcklig eller utebliven planering och riskbedömning), brister i organisationernas dokumentation (manualer, instruktioner och procedurer), samt bristande kommunikation mellan de inblandade parterna var de största faktorerna för girting. För att minska risken för girting har rekommendationer framtagits, som bl a innefattar vikten av att hålla dokumentation uppdaterad, hålla tydlig kommunikation mellan inblandade parter under bogseringsoperationer samt planera varje operation noggrant och ge alla inblandade möjlighet till återkoppling. / This essay studies the causes of girting, i.e. accidents where tugboats get pulled down and capsizes by the vessel it is towing. The study uses 14 official accident reports about girting accidents all over the world. The HFACS-MA model is used to categorize the causes of the accident into a causal chain, in order to find out which categories are most frequently present in the accident reports.  The result shows that poorly planned tow operations (with inadequate planning and/or risk assessment), deficiencies in the organization’s documentation (i.e. manuals, instructions and procedures), and poor communication between the involved parties were the most frequently found factors for girting. In order to reduce the risk of girting, recommendations have been made that includes the importance of keeping documents up to date, maintain clear communication between the parties involved during towing operations and to plan each operation thoroughly, giving everyone involved the opportunity for feedback regarding the plan.

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.

The first image depicted of sail are in Egypt and dated to the late fourth millennium BC. Around the third millennium BC the introduction of sail began in the eastern Mediterranean.Some researchers do not believe that sail have existed in Scandinavia until about 8th century AD. The reason for this is because of the lack of archaeological evidence. The question that may be asked is whether it is reasonable that it took about 3000-3500 years for the sail to getto Scandinavia from the eastern Mediterranean? The purpose of this essay is to examine and describe which indications that are available to support the occurrence of the sail in Scandinavia during the Bronze Age. Indications will be studied in trade contacts, rock art boats, and boat constructions.The study is relevant to gain a greater understanding of the Scandinavia´s movements on the open water, trade contacts and boat construction during the Bronze Age.The result reveals that Scandinavia probably had an indirect contact with areas that used sails. Indications for contact with areas in Europe are shown by imports and exports of amber,metals, artefacts and similarities between rock carvings depicting ships. Some of Scandinavia´s rock art boats seem to show attributes such as mast and sails, but it is difficult to get an understanding by looking at the pictures only. One idea is that a change is required in the keel of the boats for sailing. The result reveals that an alternative to keel may have been double steering oars. From an experimental archaeological survey of Bengtsson & Bengtsson (2011), it seems that Scandinavian Bronze Age boats have managed to get sailed. / Den första avbilden av segel finns i Egypten och dateras till ca år 4000 f.Kr. Runt ca år 3000f.Kr. uppkommer segel i östra Medelhavsområdet, Persiska viken och möjligen Indien. I Skandinavien anser en del forskare att segel inte har existerat förrän ca 700 år e.Kr., då inga arkeologiska bevis för mast eller segel förekommer. Frågan som kan ställas är om det är rimligt att seglet har tagit omkring 3000-3500 år att nå Skandinavien från östra Medelhavsområdet? Syftet med studien är att undersöka och redogöra för vilka indikationer som finns för att seglet kan ha förekommit i Skandinavien under bronsåldern. Frågeställningarna har varit: Var Skandinavien i kontakt med områden som nyttjade segel eller hade kunskap om dem under bronsåldern? Vilka belägg finns för att kontakter med områden i Europa harförekommit? Kan hällbilderna från bronsåldern i Skandinavien tolkas ha mast och segel? Vad krävs i en båtkonstruktion för att den skall kunna segla? Har skandinaviska bronsåldersbåtar haft en båtkonstruktion som klarat av segling? Teorin som antagits i föreliggande uppsats har varit Bengtsson & Bengtssons (2011) som antar att segel kan ha uppkommit tidigare i Skandinavien, möjligtvis redan under bronsåldern. Studien utfördes genom en litteraturöversikt och metoden var empirisk och komperativ då forskares åsikter, antaganden och resultat från deras undersökningar jämfördes och presenterades utifrån frågeställningarnai analysen. En avgränsning har funnits genom att undersökningen främst berört områden därmast och segel kan tolkas ha förekommit samt på platser där tidigare forskning behandlat Skandinaviens hällristningar. Ytterligare avgränsning har funnits genom att en ingåendebeskrivning av hur båtkonstruktionen hos bronsåldersbåtarna såg ut, ej har angivits i detalj, utan i stället har de funktioner som ansetts viktiga för en möjlig introduktion av segel i Skandinavien främst undersökts. Resultatet visar utifrån analysen och diskussionen kring frågeställningarna att indikationerframkommer för att möjligheten finns för att segel förekom i Skandinavien under bronsåldern.

Biocide-based antifouling (AF) paints are the most common method for preventing biofouling, i.e. the growth of algae, barnacles and other organisms on boat hulls. AF paints for leisure boats are predominantly based on copper (Cu) as the main biocide, with zinc (Zn) present as a pigment and stabilizer. Both metals are released from the paint matrix into the water column, leading to contamination of marinas which typically have only limited water exchange. Thus, the aim of this PhD thesis was to describe the use of AF paints in different regions in Sweden, as well as the associated environmental consequences with regard to contamination of the environment and toxicity to non-target aquatic snails. Using a recently developed X-ray fluorescence application, high levels of Cu were detected on boats moored in freshwaters, despite a more than 20-year-old ban, as well as high levels of tin (Sn) on 10 % of the boats, indicating the presence of (old) tributyltin paints (TBT), which might pose an environmental risk and a health hazard for people performing the paint scraping (paper 1). In addition, very high levels of Cu and Zn were measured in the biofouling material collected from the boat hulls, and this is problematic because the biofouling is commonly disposed of on the soil in boatyards at the end of each season. No difference was found in the amount of biofouling on boats coated with Cu or biocide-free paints, which implies that Cu might be currently overused in areas of low salinity and low barnacle density (paper 2). This work also introduces the use of a new species for ecotoxicological field experiments, the snail Theodoxus fluviatilis. Chronic field experiments (paper 3) revealed 6-fold increases in snail mortality, negative growth and up to 67-fold decreased reproduction in marinas, compared to areas not impacted by boating (‘reference areas’). Moreover, a higher prevalence of snails with histopathological alterations (e.g. necrosis of gills, gonads, midgut gland and parasite infestation, among others) was observed in the marinas, compared to the reference areas (paper 4). Statistical modelling indicated that the majority of the toxic effects were best predicted by the metals, most likely originating from AF paints. The results presented in this thesis depict some important aspects of AF paint use in brackish water and highlight the necessity of implementing a suitable management practice for the heavily contaminated biofouling waste in order to minimize the risk to soils. In addition, the evidence of toxicity to snails in marinas can be used as a basis to increase the public understanding of the impact of recreational boating and encourage people to choose less toxic alternatives to AF paints. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.</p>