Hullmaking is an advance in Civilization: Call to Power.
Summary[]
The third Sea Advance, Hullmaking allows for the safe exploration of the open seas. With the Longship, Civilizations can cross the oceans and raid the shore.
Great Library entry[]
With the development of clinker construction and with an understanding of celestial navigation, the Viking longships traveled as far as North America and dominated the open seas between 1000 AD and 1450 AD. However in the calmer waters of the Mediterranean, the galley remained the premiere vessel until after the 15th century.