Behind the pilot are the main ballast tank and fuel tank.

I said softly to Hansen, "Why doesn't he blow the main ballast?

'Blow seven, six, five main ballast,' Farge yelled above the din, as he tried to lift her stern.

Stop blowing main ballast,' Coombes called out above the racket.

Orders were given to blow main ballast, but the sea was faster.

I don't want to blow main ballast if I can help it.

Commander Morris, open all main ballast tank vents.

That metal represents the main ballast of their deadly missile.

Right now he's blowing all main ballast.

The U-boat's been driven down, deep down - and they'll still be blowing main ballast.