It is possible that most or all boats and rig-types used in prehistoric times in the South-East Asia-Pacific region have completely disappeared from the record, and that those recorded by Europeans in the 17th century may have been relatively recent innovations. The purpose of this paper is to introduce to the literature a new source of information on ancient boat and rig designs. This source is the information encoded in rock-art depictions of watercraft. This paper provides a technical appraisal of 18 images of watercraft from the Tutuala region of East Timor.