Loading and stability of a late 16th century Portuguese Indiaman

The stability characteristics of 16th century ships are not known with certainty, but safety issues related to floatability, stability and overloading were a cause of concern at the time. The aim of the paper is to advance knowledge in this field by developing a set of loading conditions for a typical Portuguese ship of this epoch, for both the voyage from Lisbon to India and the return voyage. This allows testing the reconstruction of the presumable Nossa Senhora dos Mártires as well as to use this reconstruction to bring a better understanding of safety and loading issues on the Portuguese East India route. Given the uncertainties about the loading conditions, several hypotheses are tested, varying the amount of ballast, the degree of overloading and the distribution of weights on board, and allowing the development of a range of plausible loading arrangements. The stability of the ship is then assessed using modern tools to develop the limit KG curve for compliance with a modern stability criterion applicable to large sailing vessels. The case study ship is a plausible reconstruction based on the analysis of nautical archaeological remains, contemporary documents and the use of modern naval architecture methods.     

A cross-staff from the wreck of the Kronan (1676)

The article deals with a cross-staff discovered inside a wooden chest on the wreck site of the man-of-war Kronan (1676), located off the east coast of the island of Öland in the Baltic Sea. It is dated 166[1], and besides now being the earliest known complete cross-staff, it is in several respects unique. A theory that the cross-staff from Kronan , due to its rough graduation and somewhat antiquated design, was used mainly for symbolic reasons, widens the fields of research and interpretation of the material culture.