The word galleon traces back to the Byzantine Greek galea, a kind of shark, and the ship earned the comparison. In the 1550s Spanish commanders such as Pedro Menendez de Aviles and Alvaro de Bazan reworked the bulky carrack, whose towering forecastle acted like a sail that could never be lowered. They cut the forecastle down, lengthened and narrowed the hull, and added a beakhead. Galleons were carvel built with flush planks, oak keels, and flexible pine masts, and they paired square sails on the fore and main masts with lateen sails aft for maneuverability. Five galleons could be built for the cost of three carracks, funded by syndicates dividing shares into eighths or sixteenths, and armed with long range demi-culverins firing nine pound balls.

The episode also looks at the grim math behind the rigging: block and tackle systems let a surviving fraction of a crew bring a ship home after scurvy and disease. Names were messy, and 26 documents call the Red Bay wreck San Juan a nao, never a galleon. In the Mediterranean, galleons first needed galleys to tow them, but at Cape Celidonia in 1616 a Spanish galleon fleet beat a larger Ottoman galley fleet with broadsides. Galleons gave way to specialized ships of the line during the Anglo-Dutch Wars.

• At Tunis in 1535 the Portuguese galleon Sao Joao Baptista, nicknamed Spitfire, carried over 360 bronze guns.
• Manila galleons crossing between the Philippines and Mexico reached 2,000 tons.
• Francis Drake captured the Nuestra Senora de la Concepcion, nicknamed Cacafuego, in 1578 with a year’s worth of American treasure.
• The English corsair Jack Ward defected to the Ottomans and taught them galleon construction.
• The Japanese built San Juan Bautista crossed the Pacific to Mexico in 1614 carrying a diplomatic mission.