I understand that they had the technology to cross somewhat long stretches of open water, but what were their motivations for doing so and how could they confidently embark without the fear that they would be lost in open ocean or sail endlessly before running out of food/water?
We do not mean in any way to discourage new answers for this question, but this very comprehensive answer by u/TheFairyGuineaPig addresses this question somewhat, as well as several others. In particular, this section deals with navigation and finding land in the open ocean.