Flood or ebb: which is kinder on the moorings?
The ebb is gentler on the buoys, but less settled. On the flood, the passage empties south as a jet, and the mooring line sits on its eastern edge. On the ebb the same water is drawn in from a wide area south of the islands, so it arrives slowly and from several directions.
| At the buoys | Flood ↓ | Ebb ↑ |
|---|
| Peak current, 4.5 m range | 0.7–0.85 kn | 0.6–0.7 kn |
| Peak current, 6 m range | 0.8–1.05 kn | 0.5–0.65 kn |
| Typical while running | 0.35–0.75 kn | 0.2–0.4 kn |
| Direction while running | steady S, ±15–25° | NE–NNW, wanders ±35–65° |
| Difference buoy to buoy | up to 0.7 kn | up to 0.4 kn |
| Just off the south mouth | 2.3–2.8 kn | about 0.9 kn |
On the flood, 989 (southernmost) and 987 take the most current. 986 sits more over the bay and lies further round to the SW, so boats on neighbouring buoys can point different ways. On the ebb the current is about half as strong, but it wanders, so expect boats to sheer about and to lie to the wind more than to the tide.
Figures are from the 4.5 m and 6 m runs. Mackay springs are typically 5–6 m and neaps 2–3 m.