A vertical passage open at top and bottom, such as the housing in which a dagger board slides up and down, or the broader passage which allows an outboard motor to do the same . An air duct to or from an engine compartment is likewise called a trunk, but only if it is relatively short and uncomplicated. Where it is long and tortuous the idiom will be to talk of ‘trunking’.

2) The fabric or plastic tubular drain that can be raised or lowered from the transom of a RIB to let any water out of the rigid hull is often known as the elephant’s truck because the fabric is often grey in colour