double bottom

Is there any information available on how much (in terms of percentage of total capacity) water ballast was there in the tanks of the Titanic's double bottom before it set off on the maiden voyage? The reason that I ask is that I read something about it in Tom McCluskie's book Anatomy Of The...

The heavy weight of the engines was causing a bend in Titanic's double bottom. Does this mean the double bottom was weakened and did the breakup start there? this would go perfectly with the V breakup theory, because the double bottom would of held on and water would seep through, causing the...