In some quadruple-screw merchant ships the outer propellers of each pair are used when manoeuvring and the two inner propellers cannot be driven astern.
Kwezinye inqanawa zorhwebo ezinezikrufu eziphindwe kane iziqhubi zangaphandle yengambini zisetyenziswa xa isixhobo senqwelo moya kunye nesiqhubi esinaphakathi azinakuqutyelwa ngemva.