The change in the material used in boat-making _______.

In the 19th century each boat was made by hand, and ownership of a sailing yacht or another pleasure boat was restricted to the rich. The advent of aluminum and fiberglass as construction materials, however,
introduced the advantages of mass production, and for the first time boat owning became a possibility for large numbers of people. As a result, the numbers of available boat styles. sizes. and types multiplied. Some can even fold to be carried overland and thus complete with a whole range of inflatable rubber boats, once used as emergency life rafts now popular for rowing, out-boarding, and even sailing.