In cruisers and some larger warships the double bottoms may extend up to the waterline and thus form part of the underwater protection of the ship against mine or torpedo .
Kwiinqanawa ezinesantya nakwinqanawa zemfazwe ezinkulu imiphantsi ephindaphindiweyo isenokwandela kumgca wamanzi nto leyo ibangela ukwenzeka kokhuseleko lwaphantsi kwamanzi kwizinto ezifana neebhombu okanye iimbhumbhulu ezinde ezinkulu.