Titanic's double-hull was a safety feature to stay afloat even if suffering a blow to out it's outside hull.
Whatever colour it has been painted. There is no single colour a hull has to be.
hull city
titan
The iceberg ruptured how many of the Titanics watertight compartments
Thomas Andrews
The Carpathia
charles proctor
Smith
Carpathia
edward john smith
The Britannic and the Olympic