Sailing Theory, Sailing Terms and Weather
Sailing Theory
The sum of all wind pressure on the sail is called wind force.
The center of that force, which is above the water, is called the
center of effort (CE). The center of the force below the surface
of the water is called the center of lateral resistance (CLR).
This is the point where all the boat's resistance to sideways
pressure is concentrated. A boat performs best when the two
forces are in balance. This is when they are positioned one over
the other in a vertical line through the boat's sail and hull.
Your job as a sailor is to keep these two forces in proper
balance so that your boat will sail correctly. You keep the boat
balanced by shifting your weight and adjusting your sail.
Your boat has weather helm when you have to constantly pull the
tiller towards you to keep the boat straight on course. Lee helm
is when you do the opposite; pushing the tiller towards the sail.
Most boats are designed to have a little weather helm. However,
too much of it can make sailing difficult in anything other than
light breezes. If your boat has a lot of weather helm, it means
the CE and the CLR are not in alignment. There is more sail
pressure aft of the CLR than forward of it.
To correct the balance, 1. Shift your weight aft (back towards
the stern).
2. Pull up the centerboard.
3. If your boat has a jib, ease (let out) the mainsail.
4. Try any combination of these.
Sailing Terms
Amidships- the middle of the boat.
Backwind- the wind flowing off the sail.
Close Hauled- one of the points of sail; sailing as close to the
wind as possible.
Dead Astern- straight behind
Flaking- Folding the sail.
Glide Zone- the distance it take a boat to stop after turning
head to wind.
Heave To- to head the boat into the wind in order to slow it down
or stop it.
Sailing Weather
The Sea Breeze As a sailor you should know about local
winds. The cause of these winds is difference in temperature;
cold air is heavier than warm air. The most popular of these
local winds is the sea breeze. Warm air over the land rises...And
is replaced by cooler air sinking over the ocean. At night the
opposite happens. The land quickly loses its heat at night and
often falls to a lower temperature than the water. This results in
a light offshore evening wind. On a lake or river, the warm air
can rise at the edges to be replaced by the cool air over the
water. This can result in a nice breeze for sailing.
Forcast for a Typical Sea Breeze Day: Morning Very Light Winds
-No Weather Systems Near -Clear Sky -High Temperatures But Cooler
Near the Shore
Afternoon: Wind coming from water starting Midday -Cumulus Clouds
over land -Clear over water- Winds Speeds 8 - 12 knots
Evening: Winds Decreasing as sun slips over horizon
Linda Cullum is from Cape Cod, MA, with a second home in Vermont.
She is the author of Learn to Sail! with Multimedia! an
Interactive Sailing training CDROM which teaches all aspects of
Sailing incliding Knots, Piloting, Rules of the Road, Weather
with digital video from Sail Magazine, narration, animation and
quizzes. Visit her site at
http://learntosail.net Wishing you the
best in your sailing endeavors!
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