Spader Business Management, Sioux Falls, S.D., a training and consulting firm, reports that new boat sales dropped 34.2 percent and average total dealership sales declined by 23 percent during the first nine months of 2009. Revenue for pre-owned boats also dropped, but only by 5.2 percent. With boat sales down, a greater percent of the dealers’ revenue comes from parts and assessories (including fabric and textile products), service, insurance and marinas.