### p77 Portugal deliberately sponsored imperialist objectives > the Avis research and development programme — for that's what it was — was systematic and effective. By the last quarter of the fifteenth century, the Protugeuse had developd a coherent system of deep-sea navigation aimed at commercial profit and underwritten by armed violence. It was based on experimentally derived knowledge of solar and stellar navigation; superior nautical charts; ships that could reliably traverse the broad reachs of the Atlantic sand serve as effective gun platforms; and steadily expanding geographical knowledge not least the wind patterns and currents of the southern Atlantic. At the core of the system, from about 1440, was the caravel. - [[Galleons and Galleys - John Francis Guilmartin#p77 Portugal deliberately sponsored imperialist objectives|View in Vault]]