Large, impressive medieval V-shaped wooden fishing structures located on the Fergus Estuary, Co. Clare, Ireland have been the subject of ongoing research funded by the Heritage Council (2008–2012) and a Marie Curie IEF fellowship (2011–2013). The weirs would have caught fish on an ebb tide and are collectively known as the Boarland Rock complex. Successive construction occurred from as early as the thirteenth century to the fifteenth century AD and possibly later. This short paper explores these structures and their relationship to channel change as expressed through historic mapping and nineteenth century commentary. Using this evidence, in combination with current dating evidence, the paper reflects upon the original siting of the Boarland Rock structures in the medieval period, the serendipity of discovery and the extent to what we see today it is under threat.