The Triangle of Speed
Have you heard of the Triangle of Speed?
This is a concept used to describe the three sources of speed and energy available to a surfer on any given wave. Understanding these three sources, and how to access them is key to generating and maintaining speed.
1. Gravity
The first source is gravity.
A wave can be thought of as a hill. The higher you are positioned on that hill, the greater your potential to use gravity as a source of speed.
If you position yourself high on the wave, your “gravity fuel tank” is full. As you move down the wave, your speed increases while your remaining gravitational potential decreases. By the time you reach the bottom, there is no gravity left to access.
This makes gravity an intermittent source of speed. It depends entirely on your position on the wave and how often you can return to a higher position to access it again.
2. Rail Engagement
If you reach the bottom of the wave, gravity is no longer available, but that doesn’t mean you’ve run out of options. You simply need to access another source of energy.
The second source is rail engagement.
As a wave moves toward the beach, water flows up the face of the wave and over the back. When you trim down the line and engage your inside rail into this flow, your board begins to interact with that moving water.
As the water connects with the underside of your rail, it is redirected backwards.
According to Newton’s third law, every action has an equal and opposite reaction; redirecting water backwards generates forward thrust for your surfboard.
A useful comparison is a fire hose. When water is projected out of the hose, the force pushes the person holding it in the opposite direction. In surfing, the same principle applies: water is pushed backwards, and the board is propelled forwards.
Rail Length and Speed
Rail length plays a significant role in this process.
The longer the rail (i.e. the longer the surfboard), the more surface area is engaged in the water flow. This means more water is redirected, resulting in greater forward thrust.
This is why longboards are naturally faster down the line than shortboards.
Because of this, longboarders rarely need to pump for speed, the rail is doing most of the work. In contrast, shortboarders must actively pump to add energy and maintain speed, compensating for the reduced rail length.
Angle and Position on the Wave
The efficiency of rail engagement depends on the angle between your board and the wave face.
At the top of the wave, the face is steep, almost vertical, while your surfboard is relatively horizontal. This creates a strong, direct interaction between the water flow and the underside of the board, making it more likely water will be directed backwards and so the energy transfer highly efficient.
As you move lower on the wave, the face becomes more horizontal. If your board remains flat, the angle between the water flow and the board becomes shallower.
At a shallow angle, the water does not direct water backwards as effectively, and some is lost by being directed off the side, resulting in less speed.
This is why, the lower you are on the wave, the less speed you generate if you keep your board flat.
To maintain effective rail engagement lower on the wave, you must increase the lean of your surfboard. By leaning the board closer to vertical, towards 90 degrees, you recreate a more effective interaction angle with the water.
This is exactly how bottom turns generate speed. By leaning the board significantly, you allow the water flow to hit the underside, be redirected backwards, and produce forward thrust.
Why Rail Engagement Matters Most
Rail engagement is the most versatile source of speed.
Unlike gravity, which is only available when you are high on the wave, rail engagement can be used both high and low on the wave, provided you adjust your technique.
For this reason, it is the most important area to focus on when improving your surfing.
A useful approach is to consciously monitor how much you are leaning your board relative to your position on the wave:
- More lean at the bottom
- Less lean at the top
3. White Water
The third source of speed is white water.
This is the most straightforward (and most “crude”) source of energy. By positioning yourself near or within the white water, you can receive a direct transfer of energy, similar to how a Newton’s cradle transfers force from one object to another.
When the white water hits your board, it propels you forward.
Like gravity, white water is intermittent, you need to be in the right position to access it. However, it has one major advantage: it is almost always available.
If you find yourself out on the shoulder of the wave where it is soft and lacking energy, you can return toward the white water to regain speed.
In this sense, white water is intermittent, but highly reliable.
Bringing It All Together
There are three core sources of speed in surfing:
- Gravity powerful but position-dependent and intermittent
- Rail Engagement versatile and accessible across the wave with correct technique
- White Water reliable but requires positioning near the breaking section
Understanding how and when to use each of these allows you to generate speed more consistently and surf more efficiently.
Watch the full video here.
