The Teifi coracle , for instance , is flat-bottomed , as it is designed to negotiate shallow rapids , common on the river in the summer , while the Carmarthen coracle is rounder and deeper , because it is used in tidal waters on the Tywi , where there are no rapids .
The Teifi coracle is flat-bottomed , because it is designed for use in the shallow rapids which common on the river in the summer . The Carmarthen coracle is rounder and deeper , because it is used in tidal waters on the Tywi , where there are no rapids .