With a prevailing Easterly against them, somebody must have tacked over at some time and spotted the islands. Either that or they stayed on the port tack all they way from the Phillippines to Mexico!
Wasn’t it the Spanish practice to treat geographical knowledge of the Pacific as a state secret, so as to maintain their competitive advantage against the other European maritime powers?
It seems hard to believe that they wouldn’t have stumbled on the Hawaiian Islands at some point.
It’s almost silly to think the Spaniards at least stumble across the Hawaiian Islands. A Manila galleon would pick up a mid latitude westerly and keep going until it hit the North American coast, perhaps as far north as Oregon; as big and spread out as Hawaii is, well... A sailor doesn’t even need to be within site of the islands, the cloud formations that form above them would be instantly recognized by the greenest hand and can be seen for well over a hundred miles. And surely the Spaniards encountered more than a handful of Polynesian seamen who would have at least been aware of Hawaii. Finally, the fact that map information is ambiguous; a right thinking treasure ship captain would carry two sets of charts - one for navigating, and one to be captured with.