What forces cause a surfboard to turn?

  • Thread starter fpjeepy
  • Start date
In summary, the term "carving" in surfing refers to turning on a surfboard, which is a combination of roll and pitch or yaw. The forces that cause a surfboard to carve are not fully understood, but it is believed that the board acts like a plane, diverting water downwards to provide an upwards force. When the board is leaned, it also diverts water outwardly, creating a centripetal force that turns the board. The shape of the board, including the rocker and chine, affects its ability to carve. Further research and understanding of these forces can improve surfing techniques.
  • #1
fpjeepy
8
4
TL;DR Summary
Leaning on an edge of a surfboard will cause it to "carve" in that direction. But why?
Summary: Leaning on an edge of a surfboard will cause it to "carve" in that direction. But why?

I was a little bummed there is not a Marine Engineering section, but there is an Aeronautical Engineering section. :frown:

The term carving describes turning on a surfboard. It is a roll + pitch or yaw or a combination of the two.

My question is what forces cause it? It is different from a boat because there is no rudder. There are fins, but these resist turning don't create it. A finless surfboard (Alaia Paipo) turns easier than one with fins. Searching for an answer on google was somewhere between comical and frustrating.

My intuition tells me that when CG shifts off centerline the board heels and the rocker of the hull bottom causes the board to turn with it, but a flat board will act the same way.

I assume the chine generates more drag on the heel side and maybe this plays a part. I know from experience that a board with soft chines doesn't turn well.

Thanks for anyone's input.
 
Engineering news on Phys.org
  • #2
My guess is that the board acts like a plane, diverting water downwards, in order to provide an upwards force. If the board is leaned, it also diverts water "outwardly", which coexists with a centripetal force exerted by the water onto the board. The board would also need to yaw in order to maintain a "forward" orientation with respect to the path it is traveling. I assume water skis operate on the same principle.
 
  • #3
I like it. So if the center of the lift force is forward of the center of mass the "outwardly" component will create a torque rotating it.

The harder the rail/chine the move lift at the edge of the board... the further the board can lean... the larger the turning torque.
 
  • #6
Even if the board is fairly flat, the front tip curves upward. In your mind, imagine turning the board all the way on its side and imagine water rushing at the front of the board. The tip of the board will be either a bit left or a bit right of the rest of the board and water hitting it is creating an off-center force which will create torque, turning the board. It would be like having a front rudder on a boat.
 
  • #7
Probably the same as turning a bicycle.

Difference would be the bike has a front wheel, whereas the 'board has a rider, pushing the back of the board outwards, centrifugally.
 

What forces cause a surfboard to turn?

There are several forces that contribute to a surfboard's ability to turn, including:

1. How does the shape of the surfboard affect its turning ability?

The shape of a surfboard, particularly the fins and rocker, play a crucial role in its turning ability. The fins provide stability and control, while the rocker (the curve of the board) determines how easily the board can turn.

2. What role does the wave play in the surfboard's turning?

The wave itself creates a force that pushes against the surfboard, allowing it to turn. The shape and size of the wave also impact how much force is exerted on the board and how it responds.

3. How does the surfer's body movement affect the surfboard's turning?

The surfer's body movements, such as shifting their weight or using their arms to paddle, can influence the direction and speed of the surfboard's turn. This is known as "weight distribution" and is a key skill in surfing.

4. Are there other external factors that can impact a surfboard's turning ability?

Yes, factors like wind, currents, and the shape of the ocean floor can also affect how a surfboard turns. These external forces can make it more challenging for surfers to control their board and navigate the waves.

5. Can different types of surfboards have varying turning abilities?

Yes, the shape, size, and materials of a surfboard can greatly impact its turning ability. For example, a shorter and wider board may be more maneuverable and easier to turn, while a longer and narrower board may be more stable but less responsive in turns.

Similar threads

Hydrodynamic forces on a foil, Reynolds number, viscosity
    • Mechanical Engineering
Replies
17
Views
3K

Hot Threads

Recent Insights

Back
Top