Christopher Columbus sailed across the Atlantic in 1492, reaching various Caribbean islands about two months after leaving Europe.
Since this was completely unknown territory to Europeans at the time, with no idea of how long before they would reach land - how would they have managed provisions (food and water for the crew)? Would they have expected only a two month journey and prepared for it? Otherwise - if their provisions were half gone with nothing but ocean around them, would they have had to make a decision whether to continue (hoping to find land and provisions before the rest on board ran out), or turn back with the hope of making a future trip with more provisions? Of course - they could have relied on rainwater, birds and fish if supplies were running low.
After 1492, future Atlantic Ocean explorers would know that it would take two months to reach land and plan supplies accordingly. How about other early explorers who had to cross large expanses of unexplored ocean (maybe Magellan?)