The Germans developed the commercial production of Polyester Resins. A British Spy stole the secret plans from the Germans at the beginning of WWII, but they only got the plans for large scale production of white resin. The British gave the information to the Americans who distributed it to Amercian Industry.
Ray Greene, in Toledo Ohio, got his hands on some of the white polyester resin and used it to make the first fiberglass boat in 1942. As pointed out by others in recent threads, the boating industry is notoriously lacking in innovation so fiberglass boats have stayed pretty much white to this day.
Ed