Parallax says :

At the risk of starting a flame war:

Uh-huh?

Most keels do NOT act as vertical wings but only provide a lateral
force to resist windage and to keep the boat going straight. To be a
good wing, they would have to have an assymetrical cross section.

No-one claimed they were a "good" wing, just a wing. Mostl planes would fly
pretty nicely with a symmetrical section if there is enough alpha applied ;-)

Steve "dons flame-proof undies just in case..."