Why headlands are the pressure points

Every headland on the UK coast interrupts the run of the tide. The sea has to squeeze around the point, so the stream accelerates, often to two or three times the rate shown offshore. Add a rising seabed, a wind blowing against the tide, and a swell from the Atlantic, and you have the ingredients for uncomfortable, sometimes dangerous, sea states. The result is a local pattern of fast water, eddies, overfalls and races that can be very different from the forecast two miles away. Learning to read that pattern is one of the most useful skills a coastal cruiser can develop.

How eddies and tidal races form

As the main stream passes a headland, it separates from the land. On the sheltered side, an eddy forms, often rotating back against the main flow. This can be a useful inshore conveyor belt, but it can also set you towards rocks if you misjudge it. A race is the turbulent boundary between the main stream and the eddy, or where the stream pours over a shallow bank. Overfalls are short, steep waves that break in the strongest flow. They are not always marked on the chart as a single spot; they can extend a mile or more downstream of the point.

The strength depends on spring or neap tides, wind, swell and the shape of the seabed. A one-and-a-half-knot stream at neaps may be three knots at springs in the same place. Wind against tide is the real multiplier. A fresh breeze over a fast stream turns a manageable race into a line of breaking crests. If the wind is force four or more and the stream is running at two knots or more against it, expect trouble.

Reading the signs on the water

• Colour and texture changes: a darker, ruffled line across otherwise smooth water often marks the edge of a race or the main stream.
• Standing waves and boils: steep, unbroken waves that stay in one place, or sudden upwellings of smooth water, show where the stream is being forced upwards.
• Smooth patches: a glassy area inside an eddy can mean calmer water, but it can also be the lull before the race. Check the chart before trusting it.
• Transits and bearings: if a landmark is opening or closing faster than your log suggests, the tide is carrying you. Use fixed objects ashore to judge set and drift.

At night or in fog, fall back on charted overfall symbols, the tidal stream atlas and careful plotting. Do not rely on seeing the race before it is close. A single bearing taken on a headland, repeated every few minutes, will tell you more than a casual glance.

Timing your passage with the tide

Plan headland by headland, not just passage by passage. Identify high water at a standard port, then adjust for local high water using your almanac. Use the tidal stream atlas hour by hour relative to high water. Aim to be at the headland at slack water before a favourable stream, or carry the stream past with time to spare. Avoid arriving at the end of a foul stream when the wind is building. Springs give more push but more turbulence. Neaps reduce the stream, but local acceleration can still be two knots or more. A few hours at anchor or in harbour beats a battering every time.

Tactical choices around UK headlands

There is rarely one right route. For Portland Bill, the classic inshore passage inside the race can work in settled weather near slack water, but it demands local knowledge and a reliable engine. In a fresh wind against tide, stand well offshore or wait. St Alban's Head and Start Point produce overfalls that extend a mile or more offshore. Off the Lizard, the stream runs hard and the sea can be confused, so give the point a wide berth if in doubt. Bardsey Sound, Ramsey Sound and the Gulf of Corryvreckan are not places to be caught at full flow, especially with wind against tide.

• Inshore eddy route: only with local knowledge, settled weather and a back eddy you can identify clearly.
• Offshore route: often smoother in wind against tide, but adds distance and exposure.
• Wait it out: anchor or enter harbour until slack. Patience is a passage-planning tool.
• Motor-sail: gives control and speed to cross a race at a favourable angle.

When conditions turn against you

If you are caught, reduce sail early, secure gear and make sure everyone is clipped on. Steer for the edge of the race, not straight through the worst of it. Use the boat's speed to punch through steep waves, but avoid slamming. If the sea is breaking, consider turning back or running for the nearest safe harbour, such as Weymouth, Dartmouth, Falmouth or Fishguard. Keep a listening watch on VHF and be ready to call for help. The sea state around a headland can change in minutes as the tide turns, so a passage that felt comfortable on the way out may be dangerous on the way back.

Above all, treat headlands with respect. They are among the most rewarding parts of UK cruising, but they reward patience, preparation and a willingness to wait for the right hour.