I get that the Seafaring ways of the Andals kind of got lost as they started to settle throughout the south, but what would it take for the peoples of Westeros to once again take to the seas (thinking here of what happened to Renaissance Era Europe)?

That’s not what happened:

The arrival of the Andals in the Seven Kingdoms only hastened the decline of the Iron Islands, for unlike the First Men who had gone before, the Andals were fearless seamen, with longships of their own as swift and seaworthy as any that the ironborn could build. As the Andals flooded into the riverlands, the westerlands, and the Reach, new villages sprang up along the coasts, walled towns and stout stone-and-timber castles rose over every cove and harbor, and great lords and petty kings alike began to build warships to defend their shores and shipping.

The World of Ice & Fire: The Iron Kings