Vikings sailed to war in drekar, warships with a dragon carving on the bow. These sturdy, lightweight ships sailed swiftly and allowed crews to row into shore to mount raids. Parts from older ships would often be recycled into new vessels, which also included the knarr, a cargo vessel.
Viking shipwrights split tree trunks into thin planks with axes and wedges. The shipwrights gained stronger planks and beams by splitting the wood along its grain. The Vikings used ash, larch, pine and elm wood in hull and deck construction, using oak exclusively for the ship's keel.
The oaken keel stretched from bow to stern and was the ship's backbone. The hull was constructed by overlapping large, flexible planks, which were fastened to the keel with iron nails. A blend of animal hair and pitch was pasted between these planks to prevent leaks. Decks consisted of removable planks laid on a lattice of crossbeams and shipwrights used a single, massive beam along the keel to support the mast.
A typical warship held 16 rowers on each side of the vessel and the ship's 20-inch draft allowed crews to row into shallow waters. The shallow drafts also made it easy to quickly disembark into water that wouldn't rise above a warriors knees, facilitating the Vikings' surprise, hit-and-run raid tactics against coastal towns.