AMES — The president of Iowa State University’s student crew club said winds that had been forecast to remain low picked up suddenly, causing a boat to capsize before the crew could return to shore, killing two crew members last week.Yaakov Ben-David, 20, a sophomore from Washington, D.C., and Derek Nanni, 19, a freshman from Normal, Ill., drowned in the accident March 28 on Little Wall Lake in Hamilton County.