TechSurf 2013 Abstracts

Short Papers
Paper Nr: 2

Systematization of the Knowledge of Relevant Signals in Evaluating the Surf Zone - Proficiency in Positioning in the Surf Zone Lineup and in Wave Catching


João Miguel Antunes Brogueira and César José Duarte Peixoto

Abstract: Contributing to the beach safety of surf zone users (bathers, swimmers, surfers), this study aims to systematize the “wave knowledge” of the most efficient lifeguards, the experienced surfers, studying their knowledge of visual cues relevant to the assessment of the risk factors of the ocean in the wave breaking zone (evidenced in their proficiency on positioning in the surf zone and wave catching), classifying indicators to assess the conditions of practice and patterns recognition in the sea and in the surf. In sport systematization, we look for means to quantify and reduce the complexity by relations between different systems, creating strategies to simplify everything that looked cluttered/ complex. We started from studies of surf science (coastal oceanography, meteorology) and surfing technical manuals. Using the categorized characteristics of existing scales for quantifying the strength of the winds and sea conditions, researching the prospective procedures of experts in adventure in extreme surf conditions, observing proficient surfers in competition, we built a classification of the signs for evaluating conditions of the sea, wind, tide, configuration and bottom depth, currents, and details of breaking waves forms. Then used it as a technical questionnaire to survey champions practitioners (male and female) and trainers who surf for over 15 years, studying the relative importance of each variable specifier in the waves-currents system, either to classify the "Wave knowledge” (Problem under study) or "Wave judgement" (Sub-associated problem), both needed to “catch waves”. As a result it was found that very experienced surfers evaluate all elements of the system-current waves, to assess the degree of risk and positioning themselves in the lineup. They consider of greater importance the factors related to identifying the location, type and intensity of maritime currents (except under conditions of small waves), as well as the swell characteristics (mainly the direction and angle of arrival to coast, height, period). They vary the importance of the characteristics of each element observed according to the wave height and for “multiple peaks”/ “lined-up peaks” wave breaks types (corresponding to ocean bottom types: sedimentary/ stable). They attend the configuration of oceanic bottom, depth and coast profile. As for the quality of the surf, they meet the general characteristics of the coastal wind and temporal characteristics of the tides. As for evaluation of wave profiles, surfers appreciate critical points focusing on the characteristics of the different sections. In assessing the strength of the surf and perception the starting point of descent, they check the height crest-bottom and the wave face characteristics, details on the wave bottom zone (ramp, slope) and upper zone (edge thickness, the lip which collapses and projects).