Treatise on Armament Technology: Logistics for River Crossings

Page 8

The Wood Jar Raft

muying original: 木罌; literally "wood-jar," referring to a raft built around wooden-framed ceramic buoyancy units

The Wood Jar Raft is constructed by lashing together ceramic urns and pots original: 甕缶 (wengfou); wide-mouthed earthenware vessels to serve as a floating foundation.

• Buoyancy and Capacity: Each individual urn or pot is capable of supporting a weight of two dan a traditional unit of weight; two dan is roughly equivalent to 120 kilograms or 265 pounds, which provides sufficient strength to carry one person.
• Assembly: To form the raft, fifty or fewer of these jars are arranged in a group. They are hooked and linked together using stout ropes.
• Structure: Spears or long poles original: 槍 (qiang) are lashed across the top of the jars to create a stable framework.
• Dimensions: The resulting shape of the vessel is long and rectangular.

Navigation and Control:

• The front of the vessel is fitted with a prow or sometimes constructed with a flat wooden headboard.
• A steering oar original: 稍 (shao); a large sweep oar at the stern used for directional control is placed at the rear.
• Rowing oars original: 棹 (zhao) are positioned on both the left and right sides to provide propulsion.

This entry highlights the modular nature of Song Dynasty engineering. By calculating the buoyancy of a single jar relative to the weight of a soldier, military engineers could scale the size of the raft (up to fifty jars) to suit the specific needs of the crossing party.