Caption: From Bangor University Menai tidal model. For mean spring tides with time from Liverpool(Alfred) HW in hours for one tidal cycle. Location at SW end of Swellies, near Britannia Bridge. Green circles are depth (compared to OD) in metres with magenta curve being a sinusoidal fit. Triangles show current (positive to NE) in knots. Vertical lines at HW-1:48 and HW+4:30 show slack at that location with depths OD+2.5m and OD-1.9m respectively.