1. Artificial Reef Design for Surfing
By: Spicer Bak, M.S.
Stevens Institute of Technology
This material is based upon work supported by the National Science Foundation under Grant No.. NSF DGE

2. Why do this? Rising Sea Levels/Wave heights
Growing Conflict with Surfer
Groups and local
Government
Long Branch, NJ - October 2006
ASBPA National Conference

3. Beach Protection Waves are a type of energy 2 basic causes of erosion
Waves = energy
Energy moves sand
Beach gets narrower
2 basic causes of erosion
Longshore Sediment transport
Cross-shore erosion
Current popular protection
Groynes - Long-shore
Breakwaters/seawalls
Cross-shore

4. Groynes - Long-shore sediment transport protection
Advantage:
Keeps sand
Encourages sea life
Disadvantage
Eyesore - not pretty
Need a field to adequately protect

5. Sand moves collects on the updrift side

6. Break waters & sea walls
Wall at edge of water
Stops wave energy
Breakwater
Parallel to shore
Dissipates waves
Don’t work well, ugly
Galveston, Texas

7. Science Of Surfing Peel Angle Velocity Wave Classification
Vortex Ratio
Surf Similarity Parameter

8. Peel Angle Used to classify the wave Surfer Velocity
Ways to classify a wave

9. Peel Angle
Classify waves for beginner intermediate and expert using the peel angle and expert, this is why some waves are preferred by beginners and others by more advanced surfers

10. Classification of Waves
BEGINNER
INTERMEDIATE
ADVANCED/EXPERT
First set of numbers are difficulty level, 2nd set are peel angles, 3rd’: Numbers on the right are surf similarity parameteer (explained later)
Hutt, Black and Mead (2001)

11. Vortex ratio (Y) = Vortex length to width ratio
Vortex ratio, a way to classify the barrel
Wave parameters used for curve fitting; vortex length (l), vortex width (w), angle (θ), and wave height (H), orthogonal seabed gradient (X’)
Mead and Black (2001)

12. Surf Similarity Parameter
ξb > 2.0
0.4 < ξb < 2.0
ξb < 0.4
Breaker Type
Surging or collapsing
Plunging
Spilling
Surfing
Terminology
‘Unsurfable’ wave
‘Tubing’ or ‘hollow’ wave
‘Full’, ‘fat’, or ‘mushy’ wave
Surf Similarity paramter ‘dictates’ type of wave from spilling surging or plunging… plunging is the best type for surfing
Surging/Collapsing
Plunging
Spilling

13. Example Classifications
Different types of waves with corresponding classifications
Mead and Black (2001)

14. Reefs Disadvantages Advantages Construction difficult Time consuming
Out of sight
Design to protect against long- shore/cross-shore
Provides:
Capability for design for surf
Adds marine life habitat
Sheltered swimming
Diving
Comparable Cost
Disadvantages
Construction difficult
Time consuming
Still an emerging technology
Mostly proprietary (as of right now)
Proprietary – ASR ltd. from New Zealand has a patent that’s been pending for 10 years, they’re mainly the only company doing this sort of work in the world right now, have a base in orlando?

15. Refraction - Energy Wave straightens out Snell’s Law E=1/8  * g * H2
(q – measured w.r.t. shore normal)
E=1/8  * g * H2
As wave approaches shore want’s to approach parallel to shore line (depth contours) wave slows down on the shallow part and causes it to rotate

16. Unprotected
Unprotected waves create to make sand move

17. Coastal protection
With protection sand stays put creates, rotates the energy of the wave making it more parallel to the shore, less sand moving down shore, creates a little sand bar inside of the reef (salient or tombolo) (tombolo is connected to the structure)

18. Design Giant Sand bags V - Shaped pattern Placed then filled
General Design of a example reef bottom left is the design for boscome UK top right is the Mt. Reef design in new zealand

19. From Boscombe ( not considered a success) currently working to re-design and fix reef

20. Narrow Neck - Aus
Both Right and left
Beginners wave on inside

21. ASR design overview india goes off
Video’s from ASR they are more or less Company plugs but interesting none the less