Authorities will beef up security in Huntington Beach this week for the Ocean Pacific Pro surfing contest, which ended last year in a riot in which 40 people were injured, 35 arrested and six police vehicles set on fire. More than 200 surfers are to compete for $66,000 in prize money in the contest starting at 6:30 a.m. today and winding up Saturday afternoon. At the city's request, the contest was moved up from the Labor Day weekend to help slim down the crowd. Last year, 75,000 to 100,000 people jammed the one-eighth mile stretch of beach Aug. 31 and the crowd burst into a riot after authorities attempted to stop several youths from stripping bathing suits from young women. Lt. Charles Poe, head of the Police Department's Beach Division, said twice as many police and security officers, bolstered by new riot equipment and training, will be at the contest. Ocean Pacific will also pay for additional city police officers.