Winds & the kayaker
Sea kayaks cope well with waves, tides, currents and extremes of temperature, but too much wind can be a real problem.
If the day of your trip is windy you can avoid problems by changing your plans. Shorten the trip. Move it to a small estuary with wooded sides, or the downwind side of a headland. On a windy day, paddle upwind to start with so if anybody gets tired, the group will have an easy ride back to where you parked your vehicles.
Light to moderate winds
Most sea kayaking is done in light winds, meaning wind speeds of less than 10 knots or Force 0-3 on the Beaufort Scale. A knot is one sea mile per hour.
A moderate wind won't create big waves on its own, but if it blows in the opposite direction to a strong current it can quickly create a rough sea of steep waves ('wind over tide' conditions).
Wind blowing out to sea will make surf waves steeper, which may be a good thing if you're a keen surfer.
Stronger winds
Force 4 winds (11-16 knots) can create quite large waves if they blow continuously for a day or so. Even without the waves, Force 4 is too much for most learner kayakers. Kayakers seldom set off to sea when the wind is blowing 15 knots. It is sometimes said that a 15 knot wind blowing directly against you (a headwind) will slow you down by 1 knot.
Force 5 winds (17-21 knots) are too much for many intermediate kayakers. It has been calculated that a Force 6 headwind will slow you down by 1.5 knots. In a Force 7 any kayaker still at sea is probably in real trouble, and even a top expert will be near the limit. See Beaufort Scale For Kayakers.
If you are opposed by a strong wind, keep up the pace until you get to shelter. If you go slowly you will be out there struggling for a lot longer. If you stop for a rest you will drift backwards faster than you expect. A 10 minute rest can easily cost you an extra 20 minutes paddling. See Leeway.
A strong wind can make kayaking on open water difficult or impossible, not so much because it pushes you to leeward as because it turns you off course. See Coping With Wind From The Side.
Also, wind creates waves. When a strong wind blows out to sea, the water may be smooth inshore but increasingly rough only fifty metres from the beach. And the further you go out to sea, the rougher the sea and the stronger the wind. An onshore wind blowing a long distance over water can create a heavy surf which makes things difficult or even dangerous. See Getting Back To The Beach.
A case history
When things go wrong for kayakers at sea, the main factor is usually a little too much wind. Global air circulation patterns and local weather mean that Britain, Norway, New Zealand and Chile have some of the windiest coasts in the world. The coast of British Columbia is also very windy, except where islands shield it from the ocean.
This is from the Sennen Cove lifeboat log for 27 December 2006: "The Norman Salvesen [Tyne class steel lifeboat] launched at 11:20 this morning following a mayday call from a group of kayakers in trouble between Land`s End and the Longships lighthouse.
Initially the lifeboat had problems locating the kayaks due to poor visibility in flying spray and rough conditions...the lifeboat found one group of 3 kayaks with three people in the kayaks and one in the water clinging on. All four were recovered onto the lifeboat. A further kayak was then located with another person clinging onto it. Both the occupant and the person in the water were recovered. The remaining people were upright and OK in a double and two single kayaks.
Weather:- Overcast; wind southerly force 5-6; moderate sea, but rough and confused in the tide race off Lands End where the incident took place."
The terrific image below shows the Norman Salvesen, all 14 metres and 26 tonnes of it, in big surf at Sennen Cove. It is courtesy of Tim Stevens, from the lifeboat pages of his site at www.sennen-cove.com
The waters off Lands End are some of the most attractive but hazardous in Europe. The tide race, reefs and frequent large swell provide plenty of challenge, which is why we use them elsewhere for an example of How Not To Do It.
Add a force 5-6 wind and even a strong team of kayakers may be better off going to the pub instead. The rescue was a success in the sense that only one person required hospital treatment for hypothermia, only one kayak was lost, and the casualties got a cup of tea and a hot shower in the lifeboat station.
The rescue required the time of 12 volunteer lifeboat crew, the launch of two big lifeboats from Sennen Cove and Penlee, the assistance of a commercial flight which diverted and circled the search area to help the emergency services find the casualties, the launch of an RAF Sea King helicopter from RNAS Culdrose, and "major incident" liaison by HM Coastguard's Maritime Rescue Co-Ordination Centre at Falmouth. Of course, everybody involved in this rescue would say "it's not about money, if you need help, call the emergency services straight away".
Northerly / southerly
A northerly wind comes from the north.
A northerly current goes towards the north.
Windward / leeward
Anything downwind of you is to leeward, usually pronounced "looard".
A lee shore is one towards which the wind blowing. If a lee shore has a wide expanse of open water to windward, it will be exposed to sizeable waves. If that open water is the ocean, there may at any time be oceanic groundswell surging over reefs and into caves. In windy conditions there will probably be a heavy surf on the beaches and waves exploding on the cliffs to send spray high into the air.
If you plan a trip along any exposed coastline of cliffs or steeply-sloping beaches, at a time of strong onshore winds there may be few places where you can safely land for a rest. An island or headland may create a shelter from wind and waves. See The Effect of Landscape, below.
A lee shore in a gale was a source of terror to the crews of old-time sailing ships. In the adventure novel Moonfleet, J Meade Faulkner describes Chesil Bank, which is a steep shingle beach 10 miles long on the south coast of England. During a southerly gale, a ship might go aground on the Bank only 20 metres from safety but none of the crew would ever reach it. The steep profile of the Bank causes waves to dump their energy violently and creates powerful undertow to drag a swimmer back out to sea.
The Atlantic coast of Europe is usually a lee shore because the prevailing wind is from the south-west.
The causes of wind
Wind is created by pressure differences in the atmosphere. See The Origin Of Wind. You have only to look to windward to get a good idea what weather is coming. Dark clouds and rain usually mean strong winds. See Predicting The Weather.
The effect of landscape
Friction
Wind speed is reduced by friction with land. It is also reduced to a lesser extent by friction with the surface of the sea. In Sailing: Wind & Current (Adlard Coles, 1953) the naval architect and dinghy racer Ian Proctor says "the speed of the wind over the sea - or any large open stretch of water - is usually roughly double that over the land". One metre up, the wind is typically about half as strong as it is twenty metres higher.
Relief
Wind speed and direction are both affected by the shape of the land, otherwise known as relief or topography. This may create either problems or shelter for a sea kayaker.
Where wind encounters a trough in the landscape or a channel between island and mainland it is likely to change course and blow along it. The wind in a river valley always seems to be blowing either up or down the valley, and the effect is more powerful in a steep-sided valley like a fjord. This happens on a large scale in the St Lawrence River valley in Canada; in the Strait of Juan de Fuca between Vancouver Island and the USA; in the Columbia Gorge through the Cascade range which is a major location for American windsurfing; in the Cook Straits between the north and south islands of New Zealand, which is why they call it Windy Wellington; and in the straits of Gibraltar between Europe and Africa, especially at Tarifa which draws windsurfers and kite-surfers from all over Europe.
An onshore wind which encounters a line of cliffs or mountain range may well change course to follow the line of the obstruction, and become more powerful and gusty.
Mountains also affect the sea downwind of them in other ways. See The Origin Of Wind.
Wind shadows and & turbulence
Where wind blows offshore, from the land to the sea, you will always find a wind shadow at water level. You can see this on the photo at the top of the page. The silver areas are smooth water. Even a low foreshore such as a beach backed by marsh will typically create a wind shadow extending ten metres out to sea. This means a continuous band along the beach with less wind and no waves, which makes a convenient avenue for kayakers on a windy day.
Where waters are sheltered by woodland there is a deeper wind shadow which may extend right across a lake. A cliff, building or even a single tree will create a wind shadow extending far downwind. In the lee of a large island, kayaking or sailing may be possible over a large area when winds generally are Force 6 or above. But if you venture past the final headland you may suddenly wish you hadn't. You may also get a surprise if you set off on flat water on a Force 4 or 5 day and paddle downwind across a channel a few kilometres wide, because that's wide enough on a windy day to create quite big waves crashing onto the downwind shore (lee shore).
On a day of strong offshore winds, you may be able to enjoy a relaxed sea kayak trip by staying in the wind shadow close to the base of a cliff. Note that there is turbulence round the edges of a wind shadow which may sometimes reach inside, so you may encounter strong gusts where river valleys reach the sea, and strong downdrafts where turbulence at the top edge of the cliff reaches down and touches the sea. You can see a gust coming, as a dark ruffled patch moving across the surface of the water, as in the photo at the top of the page.
It seldom requires any unusual attention, but on a windy day some cliffs generate powerful short-lived downdrafts called williwaws or rotors. Jim W, a highly experienced kayaker from Scotland, comments "I have never been knocked flat by downdraft as some older sea kayak texts and BCU syllabi say you will be, but that might be on account of my tenacity for staying upright. I have kayaked close in to cliffs on windy days and in my experience sometimes a downdraft can slow you to a crawl for a while. One memorable example was on the west of Skye where I went exploring close to some cliffs in the lee, and my friends stayed further out. I would estimate that although generally much calmer where I was, the downdrafts were possibly up to 2 Beaufort more than the gusts away from the cliffs, although estimating the wind speed of gusts is tricky."
Landscape features such as headlands and islands also affect waves and may create a useful wave shadow.
