The increase in diving depth necessitated by improved anti-submarine detection required that the pressure hull should be circular throughout its length, having specially-shaped domed ends, and be constructed of special quality steel .
Ukwanda kobunzulu obufunekayo bokutywilela obuphuculwe sisixhobo sokulandela umkhondo esichasenen nenkwili esifunekayo esinoxinzelelo lomoya ekumele ukuba ujikeleze bonke ubude besiqu senqanawa, obumile okwenqebesha kwiziphelo zabo, kwaye bakhiwe ngentsimbi enobulunga.