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Abstract(s)
A navegação astronómica ao longo dos séculos apresentou sempre desafios no que toca à determinação precisa da posição de um navio em alto-mar. Em 1837, Thomas Sumner, um capitão de um navio americano, desenvolveu um método inovador para determinar a posição de um navio através de técnicas no âmbito da navegação astronómica nunca antes utilizadas. O seu método ficou conhecido como método de Sumner.
Este método revolucionou a navegação na época ao introduzir novos conceitos astronómicos que futuramente viriam a ser úteis para a descoberta de novos métodos. Um desses conceitos foi a descoberta de uma nova linha de posição, a reta altura, que irá ser abordada com detalhe neste estudo.
Esta dissertação explora processos históricos e teóricos que conduziram ao desenvolvimento do método e posteriormente analisa-se a componente prática do método. Esta componente é composta pela aplicação prática do método de Sumner com valores retirados de observações reais através do sextante, aquando de duas navegações efetuadas. Este estudo tem como objetivo aferir a viabilidade do método comparando os valores calculados com as posições GPS (Global Positioning System) obtidas no momento das observações.
Astronomical navigation over the centuries has always presented challenges when it comes to accurately determining a ship's position on the high seas. In 1837, Thomas Sumner, an American ship captain, developed an innovative method for determining a ship's position using previously unused astronomical navigation techniques. His method became known as Sumner's method. This method revolutionized navigation at the time by introducing new astronomical concepts that would later be useful for discovering new methods. One of these concepts was the discovery of a new position line, the straight height, and will be covered in detail in this study. This dissertation explores historical and theoretical processes that led to the development of the method and subsequently analyzes the practical component of the method. This component is composed of the practical application of the Sumner method with values taken from real observations using the sextant, during two navigations carried out. The aim of this study is to assess the viability of the method by comparing the calculated values with the GPS (Global Positioning System) positions obtained at the time of the observations.
Astronomical navigation over the centuries has always presented challenges when it comes to accurately determining a ship's position on the high seas. In 1837, Thomas Sumner, an American ship captain, developed an innovative method for determining a ship's position using previously unused astronomical navigation techniques. His method became known as Sumner's method. This method revolutionized navigation at the time by introducing new astronomical concepts that would later be useful for discovering new methods. One of these concepts was the discovery of a new position line, the straight height, and will be covered in detail in this study. This dissertation explores historical and theoretical processes that led to the development of the method and subsequently analyzes the practical component of the method. This component is composed of the practical application of the Sumner method with values taken from real observations using the sextant, during two navigations carried out. The aim of this study is to assess the viability of the method by comparing the calculated values with the GPS (Global Positioning System) positions obtained at the time of the observations.
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Keywords
Método de Sumner Reta altura latitude pela passagem meridiana longitude pelo cronómetro