Rusty SUP's are designed to surf.
All feature similar bottom contours: Slight release in nose, Flat entry, Light concave in center, A slight double barrel vee coming into the fins, Flat off the back. All boards feature a tight bottom radius on the rails. This contributes to stability and helps to get the board up and planning more efficiently.
This is a proven, go-to, bottom design for surfboards that has stood the test of time for decades. It generates a lot of speed yet enables the rider to make smooth, controlled, rail-to-rail transitions with minimal effort.