Performing in Light Air - SailNet Community

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Old 01-15-2003
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Brian Hancock is on a distinguished road
Performing in Light Air


Light air, says the author, can be one of the most pleasurable conditions for sailing.

Perhaps it's because I have seen my fair share of rough weather, or maybe it's because I have sailed enough stormy seas to last a lifetime, but whatever it is, I really like sailing when the ocean is calm and peaceful and the wind comes in light zephyrs. The sailing might not be spectacular, but the water is beautiful to look at and I enjoy the challenge that comes from keeping a boat moving when there is seemingly no wind to propel it. Many sailors are too quick to turn on their engines and they miss out on some of the most serene and wonderful sailing conditions. It's probably because they do not know how to get a boat moving in light winds, or maybe they do not have the right sails on board, or even the patience to enjoy this kind of sailing. Whatever the case, I'd like to share some information regarding the sails you need for such conditions and how best to get a boat going when barely a ripple creases the surface of the water. The results are rewarding, so stick with me.

There is one important thing to understand about wind. Wind is energy and when it hits your sails some of that energy is used simply to fill the sails, or in the case of a spinnaker, to lift the spinnaker so that it can fill and then propel the boat forward. If you are trying to fly a spinnaker that is either too heavy or too large, what little energy the wind may have will be expended on just raising the sail, leaving none to move the boat. I know many sailors who wrongly believe that sail area is the key to getting a boat moving in light winds, and while this is true when there is a steady wind blowing, it does not hold true when the wind is light. For light-air sailing you need light sails and light means light fabric as well as smaller sails. Unfortunately, most of the small sails we all carry on board are designed for heavy air, unless we have some designed and built specifically for light-wind conditions. Many racing boats carry a sail that has long since been discarded from the cruisers' inventory. It's a sail that's perfect for getting a boat moving in light airóthe daisy staysailóand it can double as a windseeker. Let me explain.


The daisy staysail being used above is barely visible below the foot of the spinnaker, but it's likely what started the boat moving before the spinnaker filled.

A daisy staysail is a high-aspect, high-clewed, loose-luffed sail usually made from a light nylon material. These sails are intended to be set free-flying, often on a rollerfurling unit. A wire up the luff, or on more high-tech sails, a Spectra or Vectran line up the luff allows the sail to be snugged up tight so that the luff does not sag to leeward when the wind increases. This also allows the sail to be rolled away when it's not needed. In its staysail format, the sail sets under a spinnaker or light air reacher to break the slot between the headsail and mainsail, adding power to the foretriangle. It's a great sail in that application, but the daisy staysail really comes in handy when the wind is light and you need a small, light sail to get the boat moving. That's when it becomes a windseeker. You see getting a boat moving in these conditions is all about creating apparent wind. If the windseeker is able to get your boat moving, you will be creating your own wind to add to the small amount of wind that's already available, and soon you have enough apparent wind to move the boat even faster.

By having the windseeker set on a rollerfurling unit, it's a simple matter of pulling the furling line to get rid of it as soon as the boat is moving. Because once the boat gets going and you have created some apparent wind, you can utilize your larger headsail. The beauty of the roller-furling application is that you can leave the windseeker hoisted and furled until the wind has filled in to a steady breeze. At that point you can either drop the sail and stow it away, or if the wind drops again you can unroll the windseeker and catch what breeze there is.

"The second most important lesson to learn about light-air sailing is to keep the boat as steady as possible."

The second most important lesson to learn about light-air sailing is to keep the boat as steady as possible until you are able to create some apparent wind. Because the windseeker is small and light it does not add to the rolling and pitching of the boat. Often when there is no wind there will still be a persistent leftover slop in the sea state that will shake the wind from your sails. A large, heavy headsail bangs into the rigging and bounces around, hardly holding sufficient wind to fill the sail let alone move the boat forward. So sheeting your mainsail amidships and flattening it completely by either tightening the outhaul and flattening the foot, or by tucking in a flattening reef will help you to steady the boat in these conditions.

Some sailors will argue that flattening the sail removes the shape you need to develop the power needed for light air, but the shape does no good when the sail is flapping around. By flattening the sail you remove most of the loose fabric that shakes the boat around. If you can drop the sail, that's even better. Your goal is to use what wind there is to fill your lightest sail, and by dropping the main you take away an almost useless sail that only creates disturbed air at a time when you need the air to be as undisturbed as possible.


The author juices his own boat through the evening zephyrs by heading up when the kite sags and bearing away when it's drawing.

You need to understand apparent wind if you are going to get any light air performance from your boat. Apparent wind increases when you sail into the wind and decreases as the wind comes aft. If you are trying to sail dead downwind your boat speed negates what true wind there is and you end up going nowhere. Sometimes there is very little you can do if the wind is blowing toward your destination, but often it's not and you can make use of it. If you have a light-displacement boat it will accelerate quickly and in doing so drag the apparent wind forward. If that happens, bear away to keep a constant wind angle. Heavy displacement boats do not accelerate as quickly, but they do maintain their momentum (read apparent wind) longer and that's a good thing. If you are trying to fly a spinnaker you will need to head up, in other words head toward the direction of the wind to gain some apparent wind pressure to fill the sail. At first don't worry about your course; your initial goal is to get the boat moving. Head up, use what wind there is to fill the spinnaker, and as the boat picks up speed and drags the wind forward, bear away more toward your destination. As you bear away the apparent wind will decrease so hold the course as long as you can and then head back up again.

As you perfect the technique above, watch the fabric of the sail. When there is wind it will be stretched tight; as the wind decreases the fabric becomes soft with slight wrinkles and that's when it's time to steer back toward the wind again. This is a delicate tightrope to walk for the person on the helm, but if you can sail the narrow edge you will keep the boat moving. If you bear away too far and the spinnaker or the staysail collapses you will need to use some of that precious energy just to raise the sail again so watch the fabric for these critical signs.


Minimizing wetted surface as much as possible in light air is one of the keys to getting the boat moving.

The third important thing to remember is weight distribution. On some boats it's hard to affect the boats trim with crew weight alone, but on many boats just having people walk forward helps get the boat moving. By transferring the weight forward, preferably to leeward, you raise the wide aft sections of the boat out of the water thereby reducing the wetted surface. Surface friction between the hull and the water slows a boat down, so the more you can do to reduce the part of the boat that touches the water, the less friction you will experience and the more speed you will be able to generate. By moving the weight to leeward you tip the boat slightly, allowing the sails to fall more naturally, and allowing the wind to flow across them to produce power. Of course you also need to remember that your rudder can act as a big break. The more you move it around, the more it will slow the boat down. As you head up and bear away, make the changes as gently and with as little movement as possible.

There is a lot to think about to get a boat going when barely a trace of wind is available, but once you get all the small details working together you will be surprised at how quickly they add up to boat speed. Set your smallest, lightest sails and try and keep the boat as steady as possible by flattening or dropping your mainsail. Head up to create apparent wind and bear away gently once the boat picks up speed. Keep you spare weight and crew forward and to leeward, and turn the rudder as little and as gently as possible. It's a bit like dancing with a ballerina; watch that you don't step on any toes. You just need to feel the rhythm of the boat, the wind, and the sea, and let the boat guide you. It's designed to sail and if you step lightly, treat each maneuver with care, and have the right sails, you will soon be experiencing the pleasure of light air sailing.


Suggested Reading:

Using the Asymmetrical Spinnaker by Brian Hancock

Shifting Gears in Light and Variable Wind by Rich Bowen

Surviving in Light Air by Dan Neri


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