Originally Posted by zz4gta:815566
The keel works just like any other foil. It generates lift from differences in "pressure". Even though the keel is the same profile on bother sides the angle of attack is enough cause a change in pressure. There is lots of info online about this.
Angle of attack is how airplanes can fly upside down.
Okay, perfect - this is exactly the kind of statement I don't understand. Unlike the model airplanes I flew as a kid (which flew upsidedown nicely) my boat's keel as far as I can tell has zero angle of attack when I'm beating or any other course with the rudder straight.
Or do we look at the beam-on component of apparent wind as if the boat is moving laterally and say the keel is "generating lift" by resisting skid, even though of course relative to the water the boat's motion is only forward? But that seems counterintuitive as a description of what's going on...