Hi, jep142. It's good to see you back. That book sounds interesting. I have an interest in the Norse voyages to North America, but didn't know about St. Brendan. It's not too surprising that Europeans got there before the Norsemen, maybe more surprising that they managed to get back to tell the tale.
It would be fun to read the practical details of sailing that primitive boat. I hope he used modern navigation methods. Back then you had no way of measuring longitude, and latitude was somewhat crude. You filled in with a keen appreciation of weather and ocean fauna, so your directions could boil down to something like "go straight to where the whales are and turn left".