[Squawk 8888]

The challenge isn’t building boats, it’s navigation. Without a compass and a reliable timepiece, you can’t safely venture very far from the sight of land.

[presidio9]

Um, I'm pretty sure Christopher Columbus did not have a reliable timepiece.

I know for a fact that Leif Errikson sailed to Nova Scotia before the compass was introduced to Scandinavia.

[muawiyah]

There are ways ~ the Polynesians did it. Of course they had vessels capable of sailing the Pacific. The Chinese (related to the Polynesians, et al) built enormous catamarans that could have sailed everywhere on Earth if they wanted ~ but they didn't want.

You can use natural feldspar stone to find the Sun ~ that's been around for thousands of years (polarized light always gives it away).

For purposes of navigating the Mediterranean, Black Sea and waterways in Asia early man concocted a sort of celestial map ~ principal stars in constellations were related to points on the ground that might be notable landmarks or even oracle sites. That way if you got lost, you'd stop on the shore and ask the locals where such and so was and they'd tell you, then you could relate that to the celestial map and be on your way.

No clock ~ no compass ~ just a map!

Modern navigation aids enable you to travel the most efficient route ~ but without them you can still get to where you are going.