Light casings are built around the capstan gear, battery ventilation pipes and other such excrescences outside the hull to provide a streamlined form and so reduce the frictional drag of the hull .
Izingxobo zezikhanyisi zakhiwa ngakwigiyeri yekhapsteni, ngakwimibhobho yokungenisa nokukhupha umoya kunye nezinye izinto ezingafunekiyo ezikhula ngaphandle kwisiqu senqanawa ukunikezela ngendlela ethe tse nto leyo enciphisa ukukhuhleka xa kurhuqwa isiqu senqanawa.