Tides can be of significant assistanceto sailors, whether simply out for a day sail or when trying to put the miles under the keel whilst on passage, as they can often provide a significant ‘lift’ if the timing is right. On the whole tidal ranges are less than most people expect, but there are some areas where the ability to read and use both a tidal stream atlas and tide tables is important. Many sailors are surprised to learn that the strength of the tidal flow is not related to the range (other than being greater during springs than neaps). For example, typical tidal flows of approximately 1 knot within the Firth of Clyde during ‘springs’ (3.1m range) are significantly less than that found in the Sound of Islay (0.6m range, up to 8 knot tides).
Rather than attempt to try and summarise the tidal patterns for the whole country in a few words it is perhaps more useful to try and focus on the important issues. There are several ‘tidal gates’ at which the strength of the tide is sufficient to prevent progress of even a large sailing yacht if the navigator gets their sums wrong. As the flood tide follows a clockwise direction around the Scottish coast the main tidal gates will also be listed in this pattern: Kyles of Bute, Mull of Kintyre, Sound of Islay, Dorus Mor, Gulf of Corryvreckan, Sound of Luing, Cuan Sound, Duart Point (entrance to Sound of Mull), Kyle of Loch Alsh and Kyle Rhea (Skye), Pentland Firth (Orkney) and the inner Firth of Forth.
Some of these tidal gates have an infamous reputation- most notably the Mull of Kintyre, Gulf of Corryvreckan, and Pentland Firth, not least because peak flows during a spring tide at all three locations can exceed ten knots. At all of the tidal gates, and especially these three, it is very important to ensure that the direction of both wind and tide is the same. It may sometimes be necessary to push against the tide for the last hour of the counter tide in order to achieve a comfortable passage through the gate, as once the tide turns standing waves, overfalls, eddies and whirlpools can quickly develop. At other times the distance that has to be covered (for example the Pentland Firth) may dictate that you simply have to sit back and enjoy the benefits of one of the many anchorages, marinas or harbours whilst you wait for a fair wind and tide!