Wind

Wind. I could write for hours about it. How it’s generated. Why it comes from where it does. Why it changes. What is meant by backing and veering. About its force. How it interacts with a sailboat. The differences between apparent and relative wind. Points of sail. How it interacts with and changes the surface of the water. These things and more are best very well understood by those who aim to harness wind to excitedly scoot across the surface of the water….at a breakneck speed of ….uhm……3 to 10 knots. Most of us average 6 knots. Circumnavigators (cruisers and not racers) average 3-4 knots over their entire journeys.

Recent winds in excess of 45 kn in the San Francisco Bay Area wreaked havoc in Sausalito. Boats were blown around in the anchorage. One or two were grounded. A few sank. Sails were shredded. Docks were damaged. So far, this year, unlike past years, no lives have been lost on the water as a result of these storms.

Someone posted this image of a shredded headsail on Facebook.
Someone posted this image of a grounded sailboat in Sausalito on Facebook.

I’ve been to the docks in similar wind and winter storm conditions. It’s surprising how many boat owners do not have their boats properly secured given the forecasts. Often, docked vessels are rocking back and forth like hobby horses and sideways as if they are searching for their points of vanishing stability. It’s essential to keep ones vessel secured with both fore and aft spring lines as the wind shifts with the passing low pressures are going to come from all directions sooner or later. Winds from the south and north are not uncommon and represent a distinct change from our usual northwest winds backed to the west. Best to spring the boat all directions unless one is willing to look at wind predictions and alter lines on a daily basis.

Skiron is fairly secure and ready for wind conditions from any direction. Here you see the aft dock line to the cleat, a spring line from the dock cleat to midship, and a spring line from midship headed to a forward cleat on the dock. Fenders are in place. The vessel is situated in the slip such that fenders will not come in contact with the dock when wind and waves exert their influence on the unit.
The spring line is traveling fore from the midship to a dock cleat. I usually double my bow line from dock to deck cleat as shown. I dislike coiling lines on the deck and appreciate the added security of this arrangement.

It has been said that one can definitely distinguish wind of 5 knots by the feel of it on the face. Apparent wind may confuse the interpretation of true wind strength and direction. As one gains experience and hones observational skills direction and strength become much easier to predict while underway.

A number of different apps allow you to predict wind that may affect your sailing adventure. I have tried several of these and find that Predict Wind offers reliable predictions but the wind is oft greater than anticipated.

Predict Wind estimates at the moment I created this blog.
Learn to read these corresponding images!

One may gain clues regarding wind strength from both the vessel and from outside the boat.

Here are a few thoughts or questions regarding wind assessment that can be gleaned from your sailing vessel. What are your sails doing? What do they want to do? Is the vessel turning into the wind? What is the point of sail? Is the boat heeling? Is the vessel over canvassed? Are you making progress? What is the leeway? How about the position of your flag? Burgees? Where is the masthead fly? Asking these and more questions related to what the vessel is experiencing and doing can assist in making inferences about wind. Remember that most of these observations will give you apparent wind which is always forward of true wind.

Stern flag indicating apparent wind on a slight port broad reach in 20 kn wind in the Golden Gate.
Sail trim and direction of travel always provide an approximation of apparent and true wind. Old sails and 22 kn wind led to excessive heeling that was subsequently corrected by increasing backstay tension and tightening the outhaul and furling line.
The masthead fly provides apparent wind direction underway and true wind direction when stationary.
When in doubt….and only if you trust your instruments…..

There are a lot of other indicators, both on land and at sea, that provide clues to wind direction and strength. Many of these provide a source of true wind direction and speed.

A flag on land can indicate true wind direction. Strength can be estimated by the position of the flag. This flag indicates a wind speed of approximately 15to 20 kn from the direction opposite where the flag is pointing. Dad’s Luncheonette in Half Moon Bay is a pretty cool place for burger sandwiches on the weekend!
The Burgee of a stationary boat indicates the wind direction by pointing to where the wind is blowing…. the reciprocal of the true wind direction.
Trees near a harbor can provide an estimate of true wind speed and direction.
You can gain information about true wind direction and speed by observing other sailing vessels in your vicinity. This approach may also allow you to recognize when you’re about to enter a windy area such as the “slot” in the San Francisco Bay.
Wind across the surface of the water creates waves. The true wind is usually perpendicular to the longitudinal axis of the waves. You can estimate the direction of the waves, and thus deduce the true wind direction by making a few simple calculations based on your heading and the relative angle of the waves to the axis of your vessel and correcting for magnetic variation, and, if necessary, compass deviation. Learn the Beaufort scale to be able to predict wind strength based on wave height and behavior.
Swells are different. They usually arise from a distant source. One can easily determine their direction as mentioned above. They may be complicated by a secondary swell and also by wind waves. You must use your powers of observation and remain alert when out in the ocean in order to navigate the potential dangers of an unsettled sea. This photo was taken 10 nm out from the Golden Gate Bridge in the midst of 12 ft swells from the west, 2 ft swells from the south west west and wind waves of 4-6 ft from the northwest in 28 kn of wind. Some of these wave forces combined and were quite “entertaining” so to speak. Scopolamine patches work. Try it….you’ll like it!

There are plenty of other way as you can deduce true wind speed and direction. Watch the clouds. While they oft show winds aloft, anything illustrating movement under 2000 feet is fairly close to what you are an example of wind direction that you are experiencing on the water. If the clouds are higher than 2000 feet just remember that the wind on the surface is backed, rotated counterclockwise, relative to what you are seeing in the sky. If you can see smokestacks billowing smoke on land they will indicate the reciprocal of the true wind direction.

True wind from the south.

Use these methods to estimate wind….and those methods familiar to you. But, mostly, learn to feel it. To sense it. To predict it from an awareness of what is going on around you with a minimum of assessments. Importantly, learn to use what you deduce about the wind to your advantage to make progress, predict trouble, stay safe, and enjoy sailing.

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