How Does the Keel Keep Althea from Sliding Sideways?
One of the first things guests notice aboard Althea is that the boat leans gently as the wind fills the sails. Many assume that means the boat should slide sideways across the water—but it doesn’t.
The reason is the keel.
Hidden beneath the waterline, the keel is a large underwater fin that also acts like an airfoil. As water flows past it, the keel creates lift in the opposite direction of the sideways force from the sails. The sails use the wind to pull the boat forward and sideways while the keel resists the sideways motion by pushing against the water. Together, they channel most of the wind’s energy into forward motion.
This balance is what allows Althea to sail efficiently, even when traveling at an angle into the wind—a skill known as tacking. Without a keel, a sailboat would simply drift sideways, making it nearly impossible to sail upwind.
Try This While Sailing:
During your charter, watch the bow of Althea as she slices through Grand Traverse Bay. Even though the wind is pushing from the side, you’ll see the yacht steadily moving toward her destination. That’s the sails and keel working together—a beautiful demonstration of physics in action.