a peel angle less than 25° is too fast to surf. Fast: 30° Medium: 45° Slow: 60° Wave intensity The type of break depends on shoaling rate. Breaking waves can be classified as four basic types: spilling (ξb<0.4), plunging (0.4<ξb<2), collapsing (ξb>2) and surging (ξb>2), and which type occurs depends on the slope of the bottom. Waves suitable for surfing break as spilling or plunging types, and when they also have a suitable peel angle, their value for surfing is enhanced. Other factors such as wave height and period, and wind strength and direction can also influence steepness and intensity of the break, but the major influence on the type and shape of breaking waves is determined by the slope of the seabed before the break. The breaker type index and Iribarren number allow classification of breaker type as a function of wave steepness and seabed slope. Artificial reefs The value of good surf in attracting surf tourism has prompted the construction of artificial reefs and sand bars. Artificial surfing reefs can be built with durable sandbags or concrete, and resemble a submerged breakwater. These artificial reefs not only provide a surfing location, but also dissipate wave energy and shelter the coastline from erosion. Ships such as Seli 1 that have accidentally stranded on sandy bottoms, can create sandbanks that give rise to good waves. An artificial reef known as Chevron Reef was constructed in El Segundo, California in hopes of creating a new surfing area. However, the reef failed to produce any quality waves and was removed in 2008. In Kovalam, South West India, an artificial reef has successfully provided the local community with a quality lefthander, stabilized coastal soil erosion, and provided good habitat for marine life. ASR Ltd., a New Zealand-based company, constructed the Kovalam reef and is working on another reef in Boscombe, England. Artificial waves Even with artificial reefs in place, a tourist's vacation time may coincide with a "flat spell", when no waves are available. Completely artificial wave pools aim to solve that problem by controlling all the elements that go into creating perfect surf, however there are only a handful of wave pools that can simulate good surfing waves, owing primarily to construction and operation costs and potential liability. Most wave pools generate waves that are too small and lack the power necessary to surf. The Seagaia Ocean Dome, located in Miyazaki, Japan,