(1) Bung – something that fits into a hole to bung or plug it up, such as the drain hole in the bottom of a dinghy.

(2) the full-scale model, or male mould from which a hollow female mould is taken for the building of glassfibre hulls. To make a plug is a costly business; it must be very fair and accurate, with a fine surface finish, for the mould will faithfully reproduce any imperfections, and they in turn will be transmitted to all the hulls which are laid up inside it.