Semi-Structured Boats in the Yayoi and Kofun Periods of Japan: Ethno-archaeological Perspectives from Papua New Guinea

MIYAHARA Chinami

Understanding the structure of boats used in prehistoric and early historic Maritime Asia and Oceania is essential for interpreting human adaptation in island environments. This paper examines the structure and technological significance of semi-structured boats used in the Japanese archipelago during the Yayoi and Kofun periods (ca. 5th century BCE–6th century CE). Archaeological evidence shows that these vessels consisted of a dugout canoe base with added side planks, while the bow and stern were closed with vertical splash boards or cross beams. The wooden components were fastened with wedges and bindings of cherry bark. This composite structure represents an intermediate technological stage between simple dugout canoes and fully structured boats in the development of wooden shipbuilding in East Asia. Such vessels likely played an important role in inland water transport within the Japanese archipelago and in crossings of the Korea Strait between Japan and the Korean Peninsula. A comparable bow and stern structure is also observed in the Masawa-type Kula canoe once used in the Trobriand Islands of Milne Bay Province, Papua New Guinea. Although this canoe type is now rarely built, a related wooden sailing canoe known as the Sailau continues to be constructed in the Louisiade Archipelago. I conducted approximately six months of ethno-archaeological fieldwork on Panaeati Island, a major production center of Sailau, between 2024 and 2026. By combining archaeological evidence from Japan with ethnographic observations from Papua New Guinea, this study explores the structure, technology, and paddling practices of these transitional boat forms.