How Sailboats Float
Floating depends on two things: displacement and density. Archimedes' principle, which
explains the concept of buoyancy, states that in order for an object to float, it must displace an
amount of water equal to its weight. As a sailboat's weight pushes downward and displaces
water beneath it, an upward force equal to that weight holds the boat up.
Here's where density comes into play. To displace enough water to remain afloat without
becoming submerged, a boat must have an average density less than water. For that reason,
the hull of the boat is hollow. Whether the boat is made of concrete or fiberglass, its average
density is less than water. Think about it: If you put a basketball and a bowling ball in a
swimming pool, the air-filled basketball has an average density much less than that of water, so
it will float. The solid bowling ball, however, will sink immediately. This is how anything from a
small sailboat to an aircraft carrier can manage to stay on top of the water.
Surface area also helps to keep the boat afloat. More surface area gives an object a better
chance to displace enough water to offset its own weight. For instance, a small ball of clay likely
will sink before it can displace the amount of water equal to its weight. But if you flatten the
ball into a thin pancake, there is more surface area to distribute the weight across and displace
the water, so it will float.
Talking the Talk: Common Sailing Lingo
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Starboard - the right side
Port - the left side
Stern - back of the boat
Bow - front of the boat
In irons - when the boat is going
directly into the wind and can't catch
wind in the sails
Luff up - turn the sailboat into the wind
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True wind direction- where the wind is
coming from when you are standing still
Apparent wind - what you feel while
the ship's moving; the result of a
combination of the true wind and the
wind that the boat's motion forward
creates.
Trim sails - setting sails for maximum
efficiency
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