An artificial surfing reef for Scarborough?
Over the last five years, wave pools have been the last word in artificial waves. The number of companies working in the field has increased, each with their own patented spin on wave propagation, though only two have a working proof of concept, Wave Garden and the Kelly Slater Wave Company. No doubt the number of players will increase, and so will the number of ways to create a wave.
Curiously overlooked in all this has been the humble artificial reef. Twenty years ago the idea of forming a structure in the wave zone captured our imagination, it occupied the lofty space that wave pools now reside. Surfers, however, went cold on the concept after a string of artificial reefs failed to deliver.
But you can’t kill an idea and engineers by nature are persistent bastards. So as the wave pool pioneers scouted inland for cheap real estate, a few operators learnt from past mistakes, sharpened their calculations, and kept a keen eye on the wave zone.
Among those operators are Simon Mortensen and his team of surfers/engineers at DHI. Recently DHI have been commissioned to research the viability of an artificial reef at Scarborough Beach, Perth, and the team have modelled and designed a rock reef to work in Perth's low swell environment.
Scarborough Beach with ideal conditions but lamentable shape - a product of uniform bottom topography
Three possible sites along Scarborough Beach were identified as potential locations. A final site was chosen, the decision based on access to local infrastructure, existing wave climate, and proximity to natural underwater features that focus swell energy. The final two points underscore the lessons that have been learnt from past artificial reefs. The new creed is natural augmentation - adopting a ‘working with nature’ approach.
The reef, if it gets built, will be located 200 metres north of the Scarborough Ampitheatre and it’ll assume a classic A-frame shape with a few critical improvements over past designs. For one, engineers now recognise that good waves take shape well beyond the takeoff spot. Wave heights are increased when swell focusses on a shallow point beyond the surf zone - think of an offshore bombora or seamount.
To that end, the Scarborough proposal starts with a conical ‘wave focussing toe’ designed to refract the incoming waves toward the centre of the reef. From there the reef has a left-hand arm running at 40° designed for intermediate-level surfers, and a right-hand arm running at 45° for advanced surfers. Each arm is 90 metres long and will offer rides from 40 metres to 120 metres depending on conditions.
Aerial view outlining the alignment of Scarborough Reef within a natural focusing zone and the proximity of the reef to Scarborough Ampitheatre
The ability to work in a range of conditions, particularly low energy conditions, is paramount, though the report states that during Perth’s infrequent big swells the reef “is expected to produce excellent surfing conditions of very high quality.” Reassuringly, at least for those who want some grunt, the design comes with a “potential increased risk of injury.” Who says we live in a nanny state?
No doubt legalities will be drawn up but at least the ambition is laid bare.
If it gets to construction stage, the reef will be made from granite placed into position by a barge-mounted excavator. It’s also been designed so that the cost of the reef is proportional with the volume of rock required. A smaller budget will fund a smaller version: the same reef, positioned in the same location, in the same water depth, but shorter arms and hence shorter rides.
With all the research now done the agencies involved are canvassing the surfing community. If you’ve read this far please take a moment to answer the questions below.
Want to read more about the reef? Click for DHI's Feasibility Study