CORRECTION: SEE CORRECTION APPENDED; Surfboard production -- An article in Thursday's Business section about the effects of the closure of Clark Foam, a maker of surfboard materials, misstated the size of the retail surfboard market. Retail sales were $200 million nationwide in 2003, not $22 million, according to the Surf Industry Manufacturers Assn.

In a letter to customers Monday, industry pioneer Gordon "Grubby" Clark said he would close his factory after 44 years in business. Clark Foam churns out the polyurethane foam blanks for two-thirds of the surfboards made in the United States.

SUPPLY FEARS: The closure of Clark Foam, a major producer of surfboard blanks, has led to a surge in sales at some Southland board shops. Above, a surfer at Huntington Beach this year.; PHOTOGRAPHER: Allen J. Schaben Los Angeles Times