A ship must be designed for efficiency and economy, thus there is an everlasting desire for the design of better and better ships. One of the important factors which directly influence the worthiness of a design is its resistance. Throughout decades of ship design, the resistance is given top most importance as a design objective. With the increase in computational speeds of both software and hardware, there has been an opportunity for optimizing ship hulls using iterative methods of design and modification. A method for calculating resistance for a given hull geometry and to optimize it using optimization algorithms are required for achieving better hulls. The resistance is calculated using a panel method for a given hull and the hull geometry is later changed by applying Lackenby's method of longitudinal shift of stations. An optimization algorithm extracts the best possible design out of the numerous design alternatives possible.

Secondhand ship is an option to improve marine business competitiveness. It provides a way for ship owners to integrate customer market rapidly without spending many resources on producing new ships. However, secondhand ships that perfectly suit owner's requirements becomes unavoidable challenge. Ship owners may decide to modify their ships to completely fulfill their requirements. A modification method that is often implemented is cargo replacement as observed from customer and global trends. It impacts ship stability due to different cargo properties which leads to different ship physical properties, such as position of center of gravity and buoyancy. Due to this impact, some ships may have excessive or reduced stability which causes potential damages. To ensure that cargo replacement does not negatively impact ship stability, it is evaluated according to the stability regulation of International Maritime Organization and classification society. A cement carrier vessel named MV Cemfjord is used as an example ship. The cargo is replaced from cement (ρ=1.35 tons/m3) to iron ore (ρ=3.03 tons/m3) and fly ash (ρ=0.794 ton/m3). Some modifications such as cargo position and total payload weight will be adjusted to some requirements. After implementing those modifications, some stability issues due to ship center of gravity shifting are considered. Therefore, the possibility of excessive and reduced stability may follow because of this effect. This study will investigate those stability issues and define the solution to overcome them. In this study, two solutions are offered. Firstly, the ship center of gravity is adjusted bymodifying the general arrangement. Other solution is conducted through adjusting the ship center of buoyancy by adding sponsons that affects buoyancy force on the ship hull. After defining the solution, it will be visualized into physical manners, in form of the new general arrangement or the sponsons dimension. Advantages and disadvantages of the chosen solution will also be discussed. / Andrahandsmarknaden för skepp är ett alternativ för sjöfartsindustrin att öka sin konkurrenskraft. Det ger möjligheten att etablera verksamheten på nya marknader utan att behöva bygga nya skepp. Utmaningen med detta är att hitta andrahandsskepp som kan möta kravspecifikationen som den nya ägaren ställer. En modifikation som ofta implementeras är byte av frakt gods för att tillgodose kunder och globala trender. Däremot påverkar lastens olika egenskaper stabiliteten i fartyget genom att masscentrum och flytkraftscentrum förskjuts. Detta är något som kan skada fartygen. För att undvika negativa konsekvenser från lastersättningen utreds den utifrån regler som är bestämda utav International Maritime Organization och klassificeringssällskap. Fartyget MV Cemfjord används som exempelskepp under den här studien. Ursprungligen är det ett fartyg som fraktar cement (ρ=1.35 ton/m3). I den här studien byts lasten ut till järnmalm (ρ= 3.03 ton/m3) och flyg aska (ρ=0.794 ton/m3). Modifikationer rörande lastpositionen och maximal lastkapacitet kommer göras för att möta vissa krav. Efter implementeringen kommer hänsyn tas till förskjutningen av fartygets masscentrum utifrån ett stabilitetshänseende. Studien kommer utreda och presentera lösningar för att komma till rätta med dessa problem. Två lösningar presenteras. Den första lösningen går ut på att flytta fartygets masscentrum genom att ändra fartygets generella layout. Den andra lösningen går ut på att förändra fartygets flytkraftscentrum. Detta görs genom att montera volymer på sidan av fartyget (eng. sponsons) som förändrar fartygets flytkraft. När lösningarna definierats kommer de visualiseras för att jämföra skillnader i fartygets yttre dimensioner. Fördelar och nackdelar med de två alternativen diskuteras också.

[pt] No âmbito das cervejarias artesanais, foi recentemente inventado um medidor de densidade de líquidos que opera por um princípio incomum: o do deslocamento do centro de carena. Esse medidor obtém suas medições a partir da sua própria inclinação enquanto está flutuando, mas sua implementação original converte as medidas do acelerômetro em medidas de massa específica por uma regressão polinomial. Contudo, ele não faz correções de temperatura, de forma que a influência dessa grandeza é desconsiderada na regressão. Adicionalmente, o medidor não indica qual a sua incerteza de medição. Esta dissertação teve como objetivos criar um modelo matemático do fenômeno, que não foi localizado na bibliografia existente; utilizar o modelo para a obtenção de uma estimativa da incerteza de medição, comparando as metodologias de incerteza do GUM e a que utiliza o método de Monte Carlo do Suplemento 1 e utilizando a segunda abordagem para validar a primeira; executar experimentos com um protótipo de um medidor desse tipo, comparando os resultados com um densímetro de laboratório; e realizar a caracterização metrológica do medidor. Todos esses objetivos foram cumpridos, sendo que a caracterização incluiu: sugestões de procedimentos de calibração e de medição; os resultados do experimento, incluindo a distribuição esperada na saída, com média Peso de um objeto – para um sólido rígido = 1,0500 g/cm(3) e incerteza expandida máxima de U95 por cento(p) = U95 por cento(1,0000) = 0,0028 g/cm(3) (fator de abrangência k = 1,96) no intervalo de medição entre 1,0000 g/cm(3) e 1,1000 g/cm(3); equações para a estimativa da incerteza de medidores desse tipo; a estimação de uma curva de incerteza para a faixa de calibração, segundo as medições de calibração; as contribuições de cada grandeza de entrada sobre a incerteza estimada de saída e algumas sugestões de como o medidor poderia ser modificado para melhorar o resultado. / [en] In the context of craft breweries, a recently invented liquid density meter works by leveraging an unusual principle: the displacement of the center of buoyancy. This meter obtains its measurements from its own tilt while it is floating, but its original implementation converts the accelerometer measurements into density measurements with a polynomial regression. However, it doesn t make temperature corrections, so that the influence of this quantity is disregarded in the regression. Additionally, the meter does not indicate its measurement uncertainty. The objective of this dissertation was to create a mathematical model of the phenomenon, which was not found in the existing bibliography; use the model to obtain an estimate of the measurement uncertainty, comparing the uncertainty methodologies of the GUM and the one that uses the Monte Carlo method of its Supplement 1 and using the second approach to validate the first; perform experiments with a prototype of such a meter, comparing the results with a laboratory densimeter; and perform the metrological characterization of the meter. All these objectives were met, and the characterization included: a suggestion of calibration and measurement procedures; the results of the experiment, including the expected output distribution, with mean of Weight of an object – for a rigid solid= 1.0500 g/cm(3) and maximum expanded uncertainty U95 percent(p) = U95 percent(1.0000) = 0.0028 g/cm(3) (k = 1.96 coverage factor) in the measurement range between 1.0000 g/cm(3) and 1.1000 g/cm(3); equations for estimating the uncertainty of this type of meter; the estimation of an uncertainty curve for the calibration range, according to the calibration measurements; the contributions of each input quantity to the estimated output uncertainty and some suggestions on how the meter could be modified to improve the result.