Funnily enough, that would probably make the aerodynamics worse for the same reason round parachutes have a hole in the top. Without a hole, the air has nowhere to go, so it just fills the cavity with stagnant air and the drag is roughly equivalent to just a flat shape. With a hole in the bottom, now the air has an escape route to take, but it takes a lot of effort to push that much air through the smaller hole, meaning the drag is incresed significantly

This is the only issue with drilling holes in the boat