Clinker and Carvel build hulls
Already around 190 AD a construction began to develop. This was preferred by Nordic shipbuilders. Especially the vikings built their long ships in the "clinker" construction method. Planks, or strakes were laid on top of each other and fixed with iron nails. The overlapping timbers were then strengthend with light cross frames. This means that the planking was built first and the frame was later adapted. This construction was the preferred method in northern europe until the middle ages.
Clinker construction on the Gokstad ship, 9th century
Around the 7th century AD, Mediterranean shipbuilders began to simplify the system of hull construction. They reduced the size and importance of the pegs, which connected one plank to another, and instead placed much greater emphasis on the frame. This created a strong bow in the hull, which was labour-intensive to build. In the year 1000 they had begun to abandon the pegs altogether. This type of construction, known as "carvel", was relatively cheap, but required the frame or ribs of the ship to be at least partially attached before the planking was done.
Carvel construction on the Mary Rose, 1545
The practice of frame construction initially required more planning but allowed greater flexibility in shipbuilding and eventually led to the use of plans, initially in galleys. There is clear evidence that this happened in Venice in the 15th century, although it may have started two centuries earlier. The process spread slowly, but it was the beginning of the shipbuilder's transition from craftsman to naval architect, and the use of plans also opened up the possibility of much larger ships.