 In
Search of the Perfect Wave
by Vic Davies
© 2008 Pools and Spa Marketing
Moving water is an essential ingredient of any
successful commercial aquatic facility.
Man has always had a fascination with moving water. Over the past
four decades, many varied and successful attempts have been made
to recreate the natural ocean phenomenon and utilize it both outdoors
and indoors in a controlled environment, which has resulted in great
strides in marine and ship design.
 It
has also become a central competent of outdoor water parks and,
over the past two decades, the indoor aquatic facility.
While no human-made creation can fully replicate the wild organic
surf created by nature, this popular feature found in modern recreation
centres is a guaranteed draw for bathers. There is no end to the
excitement when a wave machine is generating a series of waves that
can be varied in pattern and height, making a sea of heads bob up
and down in unison in the water.
DESIGN HAS TAKEN ON MANY FORMS
Pioneered in Europe, primarily Germany, Holland, and the United
Kingdom, the design of wave machines has taken on many forms. Earliest
reports of its use in the UK date back to 1936 at the Portebello
open-air baths in Edinburgh. This was the only known pool with operational
wave-making equipment in the UK until the "surge" of new
wave pool construction began in the early 1970s.
Wave pools eventually made their emergence in Canada in the early
1980s. At that time there were primarily three established methods
of successfully producing artificial waves.
 Swing
Arm
This type of equipment involved submerged movable parts. This method
has been somewhat abandoned over the years in favour of compressed
air since it involves less maintenance, is more economical, and
has no submerged moving parts.
Column of Water
This was first used in Arizona in the early 1970s in a large lagoon
in the city of Tempe. The lagoon was about 122 x 92m (400 x 300
ft) in size with a maximum depth of 2.7m (9ft) and was provided
with water treatment equipment. The waves were 1.5m (5ft) high,
so surf riding could be enjoyed. The water was pumped to a prearranged
height at one end of the pool. It was then released through underwater
gates and flowed over the weir (reef), forming the waves, which
swept across the lagoon. This method has since been modified and
further advanced. Affectionately know in Britain as "the dump",
it can now create tidal waves up to 3m (10ft) in height for boogie
boarding and surfing. This method is somewhat limited indoors by
the space required to achieve such large waves and the waves' sporadic
nature.
Compressed Air
This has become the most widely used and extensively developed
wave making method over recent years, and has resulted in many patented
systems to create an infinite variety of wave patterns and sizes.
Utilizing compressed air, the waves are initiated in a subdivided
concrete chamber, which usually extends along the shorter width
at the deep end or "throat" of the pool. Compressed air
is introduced onto the surface of the water in the chambers, creating
oscillation of the water, which results in wave generation in the
pool. Utilizing computer control, many different wave patterns can
be introduced by varying the oscillation times and alternating the
use of the chambers.
More Innovative Solutions Available
Today, many more innovative and grandiose solutions are available
to create large waves in a pool. However, the most popular and economical
method of wave creation remains the compressed air method.
So, what is involved in the design and construction of a commercial
wave pool?
Wave pool designers must clearly understand the basic physics of
wave movement and the pool containment tank. To create a successful
wave in a pool, a crest, a trough, and a wavelength must be produced.
 The
crest is the highest point of the wave and the trough is the lowest
point and the wavelength is the distance between any two crests.
The midpoint between the crest and the trough represents the static
water level.
Designers must also understand the importance and significance
of correct freeboard in a wave pool (the distance between static
water level and the level of the pool surround), since this is the
most important function of water retention in the pool. If poorly
designed or misunderstood, this would result in significant water
loss or an overflowing pool.
The ideal physical shape of the wave pool is a fan shape often
seen at outdoor facilities, where size is perhaps less of a restriction.
The wave is generated in the throat of the pool (the narrow end)
and forced along the surface until it breaks at the wider section
of the pool, when the trough of the wave meets the sloping floor
of the pool. The pool floor must have a maximum slope of 2.5 in
30.5 cm (1 in 12 inches) to a depth of 1.5m (5ft), usually starting
from a beach entry.
In the 70's and early 80's, wave machines were used extensively
throughout the United States in outdoor water parks. Larger areas,
which were required to accommodate large pools, to accommodate big
waves, had become the norm. The minimum area for a wave pool recommended
by North American manufactures was 557 square metres (6,000 sf)
and the wave needed to be a minimum of 0.9-1.2m (3-4 ft) in height.
To be successful indoors, the outdoor wave pool had to be scaled
down to a size both conductive to indoor use and to suite municipal
budgets. Pool designers were forced to become more adventurous and
creative with their designs.
As a result, the layout and design of an indoor wave pool now takes
into consideration many things including:
- Reflection - Wave changing direction from hitting reflective
surfaces.
- Diffraction - Bending of waves as they interact with
obstacles in their path.
- Interference - Two waves coming into contact (colliding
with each other).
 Smaller
waves, 0.6-1m (2-3.2ft) in height, become the accepted and recommended
size to suit smaller 278-371 square metre (3,000-4,000 SF) indoor
wave pools to minimize freeboard around the pool and reduce the
"cavern like" effect of perimeter walls.
Waves Now Turn Corners
Waves can now be designed to turn corners and serve up turbulence,
creating big splashes or gently lapping on the beach entry.
Other elements introduced to indoor wave pools to make them more
exciting include:
- Rapid channels, which catch a piece of the wave and regenerate
it back onto itself to create more interesting areas of "splash"
within the pool. Swimmers play in the currents and catch rides
along the river's flow, or walk against the current. This gentle
form of physical there is ideal for those who cannot tolerate
the warmer temperatures of spas or hot tubs.
- Underwater ledges, weirs, islands, boats, decorative features
and interactive waterplay devices create interest and exciting
places and areas of respite within the waves - all to provide
the "entertainment factor" and simulate more closely
the natural phenomenon of ocean shores.
- Extensive deck level access nullifies the freeboard at specific
points of entry. Toddlers can paddle along the beach entry with
waves lapping at their toes while older children can surf the
waves in the deeper waters of the leisure pool.
- The utilization of a wave equipment air compressor for the other
uses within the pool such as bubble machines, etc. The play value
and therapeutic benefits of bubbles, currents, and sprays are
endless.
- Theming was introduced to give character and identity to public
spaces by adding artifacts and particular design features that
are true to a period, place or story.
The message is loud and clear, "If we can't take the people
to the ocean... let's bring the ocean to the people".
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