Surfing Explained: Ep8 Surfboard Rocker for Speed & Maneuvers

In this weeks episode of Surf Simply's animated surf science series, 'Surfing Explained', we explore the effects nose/ entry and tail/ exit rocker has on the surfers speed and maneuvers.
This episode was written and animated by Surf Simply Coach Will Forster.
Transcript:
The rocker of a surfboard is the curve that runs from nose to tail when viewed from side-on which allows the board to roll nose to tail like a rocking chair. I would love to be able to give you a simple metric or equation to describe different rockers, but unfortunately, because they are compound curves, the only way to do it is by measuring up from the floor at intervals to get a rough idea.
Until recently, surfboard outlines and rocker templates were mostly compared by eye and experience, which made it challenging for us civilians to develop a confident opinion. Luckily many boards are now designed with computers, that can allow us to compare rocker profiles, helping to increase our understanding and refinement of their design.
Like much of surfboard design, we can understand the basic effects of increasing or decreasing the rocker on a board by looking at the same sliding scale we spoke about in previous episodes, with Speed at one end and Manoeuvrability at the other, as it’s these 2 attributes that will be most affected, with flatter boards generally being faster, and banana shaped boards having better manoeuvrability.
A Surfboard’s Rocker is generally described in terms of it’s Nose rocker and Tail rocker, sometimes called Entry and Exit rockers depending on who you talk to. In some designs, these 2 curves join in the middle in what’s called a Continuous Rocker, while in others they flatten out to create a straight region in the middle of the board, often referred to as a Staged Rocker.
With that in mind, and much like the last two videos, we are going to split the board in half and talk about the front and back halves of the board separately, though both will be contained within this one video.
So, let’s start with the entry rocker and the front half of the surfboard.
If we were to compare two surfboards with otherwise identical dimensions, though one with entry rocker, and one without, it might become somewhat easier to predict where and why entry rocker might improve the board's performance.
If taking off on steeper waves jumps to mind, then you’re right! But we’re going to start earlier in the surfing process, with paddling and catching a wave.
Entry Rocker - Paddling.
When at paddling speeds, a surfboard has to push the water aside like a ship, and this creates a bow wave. The steeper the curve of the entry rocker, the greater the bow wave as we paddle and push through the water, since the water is less able to escape over the nose or around the board following the nose outline.
To get the board up “on the plane” a vessel needs to ride up over it’s own bow wave, so boards with more rocker and greater bow waves require more energy to achieve this, and we will have to compensate for these disadvantages by paddling stronger or taking off on a steeper wave to find that extra needed energy.
Entry rocker - Steeper Waves.
When taking off on a steeper wave, however, we can see that the greater rocker template matches more so the curve of the wave, this becomes most important when reaching the bottom section of the face where the wave transitions into flat water. This means that less weight on the tail is required to maintain the nose above water whilst dropping down the wave face. So although we are at a paddle speed disadvantage, we now have a manoeuvrability advantage when dropping down the wave face on a steeper wave.
The final part of this pro/con equation for entry rocker is that when up and riding and making trimming or carving turns, the lifted nose from entry rocker reduces the chance the nose or forward rail will catch during a turn, as the material is simply lifted away from the water, so again increasing the maneuverability.
Exit Rocker
Exit rocker again fits onto our speed and maneuverability sliding scale. But as with the board’s outline it's whilst up and riding where the effects of the back half of the board become apparent.
If you are familiar with the stages of a carving turn, like shifting our weight back to lift the nose and disengage the rails, allowing us to pivot off the fins, then you might be able to imagine why exit rocker helps in this process.
Since our intention is to lift the nose and rail out of the water, by increasing the degree of the arc in the rocker, we will allow the nose and rail to lift either sooner, or with less energy and weight shift.
For the final part of this puzzle, I want you to imagine traveling in trim, parallel with the wave. It is our rail engaged in the wave face that helps us generate speed, for more on this, check out episodes 1 and 2 if you are curious about this process....(description word limit reached).

[@WEEBER13]

These are the EXACT videos I have been looking for! TY!!

[@mathewwhittle10]

Started watching you guys a decade ago... helped me transition to surfing along the wave rather than towards the beach. You are the one positive thing to have come from this pandemic... absolutely class advice!

[@SurfSimply]

Glad you’re enjoying it Mathew!

[@NotnaRed]

Perfectly explained. I never really understood how surfboards work. This series of videos cleared it up for me

[@SurfSimply]

Happy to help!

[@NadirOnTheGo]

Every time I hear a northern English accent talk about surfing, I am surprised that people actually surf up there

[@PhillHalloran]

These videos are great. I think about the dynamics of surfing a lot, and I find the variety of ideas that you and your team present challenging. There's an explanation for everything we feel when we surf and as surfers we all try to narrow down why things happen the way they do so that we can improve. I'd like to offer my own opinion on an interaction you mention for I'm not convinced that a low pressure region at the tail of the board is "sucking" water in an upward direction. You say that during trimming, with more rocker we should imagine that there is more weight at the back of the board. This is accurate and is a useful mental tool for surfing, although I think the cause is not a result of the board and water exchanging momentum at the tail, but a difference in the centre of lift. With more rocker, the centre of lift is further forward. To then counter this force so that the net torque of the surfer and board is zero, the surfer must shift their weight further forward than usual, as if "there is a weight on the back of the board". I'd love to hear what you think about this different perspective. Thanks for the great content and food for thought.

[@SurfSimply]

Hi Phill, thanks for writing and showing an interest. There’s nothing more we love than discussing the potential sciences especially considering there is so little real evidence so instead we have to deduce as a community! Its an interesting idea, I’m going to speak with our team and get some feedback on it. Thanks again, Will

[@lukehunter3902]

Keep up the great videos!!

[@4everfortalboy]

changed my life thank u so much

[@maubarbero]

Just amazing!!! thank you so much :)

[@SurfSimply]

Glad you enjoyed it Andres!

[@frewuill]

Awesome explanation. Thank you!

[@SurfSimply]

Thanks for coming back Frewuill!

[@user-rh3xf8fm4m]

Thanks for sharing

[@tonybeatbutcher]

Tnx for boosting a personal talk with yr shaper. I dig the videos so much. Are you gonna do a video about channels (mid/tail) and what they do rockerwise, someday?

[@SurfSimply]

Hi Tony, I’m glad you’re enjoying the videos. This Friday’s episode is about the bottom contours!

[@surfsenegal]

This was a sick video

[@SurfSimply]

Thank you Pierre!

[@danielforpilz]

That videos are amazing! May I ask what type of Video editing program you use for your graphics, drawings, ... I am a teacher and looking for a tool to create exactly that kind of videos, but haven't found anything convenient yet...

[@SurfSimply]

Hi Daniel, I use a mix of Photoshop to make the components, then After Effects to animate them.

[@rvrrb]

bigger boards require rocker or they don't turn. a small board under six feet require very little rocker.

[@vladzhibak678]

First one to watch it ))

[@NotnaRed]

Last one to get laid.

[@vladzhibak678]

Sorry for you. I'm sure you're going to find that special someone one day 🤙

[@NotnaRed]

@@vladzhibak678 thanks 🤗