This week, keen sailor Sian Pari Huws stands in for regular presenter Adam Walton, for a particularly nautical Science Café. Sian sets out from Holyhead on a voyage of scientific discovery aboard Bangor University's research ship, the Prince Madog. With her are a team of ocean scientists who are investigating the impact on the environment of a planned tidal energy scheme.

Sian talks to Mike Roberts, from Bangor's Centre for Applied Marine Sciences, about how the team build a detailed picture of the sea bed. Marine biologist Dr Hilmar Hinz tell Sian about the creatures they might encounter and how they might be affected by the currents. And Sian meets a fellow passenger she didn't expect to find on board a research vessel - the Welsh Assembly Member for Arfon, Alun Ffred Jones. He's been paired with Dr Simon Neil from Bangor's School of Ocean Scientists in an exchange scheme to learn more about each other's work.