In all designs adequate stability, both when on the surface and submerged, can usually be achieved only by the provision of special ballast low down in the ship, usually packed in a strongly constructed ballast keel which facilitates docking and bottoming on the sea bed .
Zonke iintlobo zokuyilwa kozinzo, xa inqanawa ingaphezulu naxa ingaphantsi, zingaphunyelelwa kuphela kunokhuphungulwa umthwalo onzima enqanaweni, odla ngokupakishwa uzizinto ezinzima zokuzinzisa inqanawa ezomeleleyo ezincedisa ukwenza idoksi nokwenza umphantsi kumgangatho wolwandle.