Stern-Frame, Boss-Arms and Rudder
The Titanic's stern was unique in that at the top was a hawser pipe, through
which a steel wire could connect to a central bower anchor, additional to
the usual anchors at port and starboard. The advantage of this was that
the weight of these side anchors could be reduced. The Centre bower anchor
weighed 15.5 tons while Side anchors weighed just 8 tons.
The stern frame, made from mild cast steel, was connected to the frame by
iron rivets- 2" in diameter. Overall, the weight of the rivets was
estimated as over a ton. Extra care was taken when fitting these so that
the joints were extremely strong.
The boss arms were also mild cast steel and particular attention had to
be paid when angling these boss arms so that the flow of the turbine propeller
would be smooth through water. The boss arms were made of two pieces, connected
along the centre line of the ship by deep flanges, which formed a web criss-crossing
the vessel.
Any 2 of the 16 watertight compartments on the ship could have flooded without
having any effect on the safety of the vessel. In any event of water penetrating
the ship, floats beneath the watertight doors (between each section of steel
bulkheads) would close the door automatically. Today, this wouldn't justify
claiming a ship as "unsinkable," but for the White Star owners,
in 1912, it did.
The Rudder
The rudder, like the stern-frame, made by Darlington Forge Company Ltd.,
was of high quality solid cast steel. It was built in five sections, elliptical
in shape.
A special feature was that the screw jackets on the bottom of the rudder
could be used for lifting it into a dry dock. The weight of the rudder was
105.25 tons; its length- 58'8" with an overall width of 15'3".