<human>:  Why did the Vikings use a clinker-built ship?
<bot>: A clinker-built ship is one in which the planks are joined together with wooden pegs. The Vikings used clinker-built ships because they were cheap to build and could be repaired easily if damaged. The Vikings were very good at shipbuilding, and built the world’s first ocean-going longships. These were clinker-built ships that were used for raiding and trading.