Wednesday, December 18, 2013

Running with the Wind

Sea Dragon sails wing-on-wing: the mainsail is
on the left and the staysail is on the right. Photo by
Alice Alpert
Heave to. Raise the main. Ease the jib. Tack! Like our scientific vocabulary, sailing terms can seem like a foreign language, but on Sea Dragon we use them all the time.  

Sea Dragon is a cutter-rigged sloop--a bit of a tongue twister, but here's what it means. There are three sails: the mainsail extends back from the mast, the staysail is forward of the mast supported by a stay line, and in the very front is the jib. We adjust the size and angle of these three sails in order to catch the wind in just the right way.

Size is simple. We want to use as much sail area as possible without "overpowering" the boat, which makes it difficult to steer and increases our chances of ripping a sail. If the wind is strong we can reef the mainsail--roll up the bottom of the sail and lower the head to decrease the area we present to the wind. Changing the angle between the sails and the boat is called "trimming." Given the direction we are sailing, the air should flow past both sides of the sails smoothly. Small pieces of fabric called telltales show us how the air is moving across each face of our sails. We use ropes called "sheets" to trim the sails until the telltales are lying flat against the sails and not flapping.

In general there are two kinds of sailing: downwind and upwind. Sailing downwind is simple, we just present as much sail area as possible and allow the wind to push the boat forward through the water. Going straight downwind, we put the mainsail out to one side and the staysail or jib out to the other. This is called "wing-on-wing."

We use lines and winches to trim the sails. Wraps around the winch
create friction to hold the line in place. Photo by Alice Alpert

But it's going upwind the Sea Dragon really has wings. The idea of moving forward using wind that is coming towards us is a little bit counter intuitive. In this case, "close hauled," the sails become airfoils like the wings of a plane, except that the wings are turned vertically. The wind rushing past the curved sails generates lift that propels the boat forward. We can't sail directly into the wind, but this technique works if the wind is more than 45 degrees off the direction we want to travel. To go straight into the wind we must tack: sail 45 degrees off the wind in one direction, then turn and sail 45 degrees from the wind in the other direction.

Going upwind, the wind pushes the sail over and the boat will lean or "heel" in one direction. We heeled strongly to port (left) on our passages to Martinique and Barbados and experienced life at 30 degrees, which was so exciting that it sometimes knocked us out of bed!

Looking up Sea Dragon's mast you can see the stays holding
the mast up. The mainsail is on the far left, the staysail in the
middle, and the jib on the far right. Photo by Alice Alpert
I love how sailing weaves human engineering together with the natural world. The boat is an amazing system of sails and lines and aerodynamic shapes and hand operated winches and pulleys that uses air currents to move along.

But while we take advantage of the wind, we are also completely at its mercy. There is a constant give and take, and the sailor is at the center of it all.

Now on our passage to Curacao we are "running with the wind," traveling almost directly in the same direction as the wind. On night watch with a full moon, the constantly moving surface of the dark water reflects the moonlight like liquid obsidian. The sails stretch out like wings and Sea Dragon seems to glide along. Standing at the helm of this powerful boat driven by the far more powerful wind is amazing at any time, but tonight it feels magical.

-Alice Alpert

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