Answer:
One of the most important advances was the development of cartography. Europeans created pretty accurate maps that allowed them to sail on the open sea. Of course, they created the maps of the Old World, as they didn't know about the existence of Americas. Another important invention was the astrolabe. This was a navigational instrument, that helped them navigate easier by measuring the altitude of the stars. With the compass, that was designed by the Chinese, the era of exploration was about to start.
Step-by-step explanation:
Europeans were attracted to the wealth of Asia since Crusades and established good trade links with China and India. Still, those links were cut off when Ottomans conquered the regions that were on that road. That is why Europeans decided to find a new sea route, of course with the help of this technological advances.