Concave or Contours: While you’re riding a wave, water is being funneled across the bottom of your board from nose to tail. When you channel this water in different ways you will get different responses. A concave board should surf faster because the concave increases surface area on the water which increases flotation and speed. The only down side is with the increased surface area there is a greater force at work against turning.

Flat:(no or little concave) Good all around bottom better for heavier surfers that may plow (push) water with the concave.

Single Concave: Best for clean surf and lighter surfers.

Double Concave: This is really a single concave towards the center of the board faded into a double concave into the tail. It is looser than the single concave and therefore is used in about 85% of the short boards on the market.

Vee: Looser than the other concaves especially if you have a heavy back foot. It is used mostly on semi-guns and guns to help control speed on big waves.