Injin waje wani tsarin motsa jiki ne da aka ɗora a wajen jirgin ruwa. Yawanci yana ƙunshi inji, akwatin gear da farfela, duk an shigar da su a cikin raka'a ɗaya. An ƙera waɗannan injinan don a cire su cikin sauƙi kuma a haɗa su zuwa mashigin kwale-kwalen, suna ba da damar shigarwa da kulawa kai tsaye. Injuna na waje suna zuwa da girma dabam dabam da ƙimar wutar lantarki don dacewa da nau'ikan girman jirgin ruwa da aikace-aikace.