A surfboard rail is basically the edge of a surfboard, and since it spans the length of the board, it's a very important feature.
The shape of the rails determines how easily water flows over the board, which in turn impacts the maneuverability and the ease with which it cuts through the water.
Types of Rails
The main consideration when choosing a rail is whether to opt for hard rails or soft rails.
Despite what the name suggests, it refers to the shape of the rails and not the material or hardness.
Hard Rails vs Soft Rails
Soft rails are rounded, smooth, and have no straight or defined edges.
They are often found on longboards and are great for buoyancy and stability while providing a lot of drive.
They don't turn as sharply or as easily as hard rails, but they are fine for paddling and for smaller surf.
A hard rail, on the other hand, has a defined edge and may form a corner at the bottom of the board.
The hard edge allows for sharper turning and while it sacrifices some stability, it gives experienced surfers more maneuverability and greater control.
Other Rail Types
You'll often see surfboard rails being described simply as "hard" or "soft", but the rail foil, which denotes its proportion, also needs to be considered.
50/50: A balanced foil whereby the widest point is the mid-point. Often seen in small wave boards.
60/40: A slightly disproportionate foil whereby the widest point is pushed away from the center of the board.
80/20: The apex is much closer to the bottom of the board. These rail shapes are more common in high-performance boards.
You may also see terms like "Round Rail", "Down Rail", "Rolled Rail", and "Down-Turned Rail".
Other Things to Consider
The shape of the rails is not the only consideration when choosing your surfboard.
The tail shape is also key, with a wider tail providing more stability and a swallow tail or round tail being more suitable for beginners.
Unless you're an experienced surfer, you really don't need to concern yourself with these things.
Your first surfboard should be a basic longboard that suits your weight and your budget and looks the way you want it to look.
If you're opting for a custom board, ask your shaper about rail types, tail types, fin placement, and other such factors, but it's best not to overcomplicate things to begin with.