In larger ships there may be two or more of each to guard against complete immobilisation of the main machinery by one hit from a torpedo or mine.
Kwiinqanawe ezinkulu kunokubakho ezimbini ekanye ezininzi kwigumbi ngalinye ukujonga ukungasebengi ekupheleleyo komatshini oyintloko ngenx yekubethwa yimbumbulu enkulu (torpedo) ekanye ibhombhu.