David 1939, p. 666, suspects these were vessels that had overwintered in Portugal. David, Charles Wendell (1939). "Narratio de Itinere Navali Peregrinorum Hierosolymam Tendentium et Silviam Capientium, A.D. 1189". Proceedings of the American Philosophical Society. 81 (5): 591–676. JSTOR985010.
Cushing 2017, p. 52. Cushing, Dana (2017). "The Siege of Silves in 1189". Medieval Warfare. 7 (5): 48–53. JSTOR48578126.
medievalists.net
Makki 1994, pp. 73–74, says this took place five months after the fall of Silves, which would put it in February 1190, but Lay 2009, pp. 157–159, places it in April. Slaughter 1968, p. 43, says specifically that he had landed in al-Andalus by 23 April. Makki, Mahmoud (1994). "The Political History of al-Andalus (92/711–897/1492)". In Salma Khadra Jayyusi (ed.). The Legacy of Muslim Spain. Brill. pp. 3–87. Lay, Stephen (2009). The Reconquest Kings of Portugal: Political and Cultural Reorientation on the Medieval Frontier. Palgrave Macmillan. Slaughter, John E. (1968). "The Conquest of Silves: A Contemporary Narrative"(PDF). The Journal of the American Portuguese Cultural Society. 2: 25–44.
Lay 2009, pp. 157–159. Slaughter 1968, p. 43, says the siege began by 5 July. Lay, Stephen (2009). The Reconquest Kings of Portugal: Political and Cultural Reorientation on the Medieval Frontier. Palgrave Macmillan. Slaughter, John E. (1968). "The Conquest of Silves: A Contemporary Narrative"(PDF). The Journal of the American Portuguese Cultural Society. 2: 25–44.