"Vintage Japanese Junk-1871," ポスター

Traditionally, the hull has a horseshoe-shaped stern supporting a high poop deck. The bottom is flat with no keel (similar to a sampan), so that the boat relies on a daggerboard, leeboard or very large rudder to prevent the boat from slipping sideways in the water. The largest junks, the treasure ships commanded by Zheng He, were built for world exploration in the 15th century, and according to some interpretations may have been over 120 metres (390 ft) in length. "The rudder-post is made of elm, (for strength) or else of langmu or of zhumu."