there is also a set of "fins" made by specialty jet that bolt onto the outside of the shoe. You fill the tiny gap between the fin and shoe with silicone. These fins are angled away from the shoe so they do a couple of things, 1) reduce caitation by forcing more water into the shoe, 2) help the boat turn more sharply by reducing slide, 3) help the boat get on plane quicker. I recently purchased a set for my flat bottom alumaweld and they worked wonders.