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Rudder
Head of Olympic in the Lathe.
The Engineer /
Author’s collection |
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After
Shaft Brackets of Olympic Being Unshipped - The after shaft brackets of Olympic
being off-loaded onto the slip from the deck of the floating crane.
The Engineer /
Author’s collection |
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Stem - Titanic’s stem
formed the foremost end of the hull. The castings and bars which formed the stem and
forefoot were supplied by the Darlington Forge Co. The stem was straight in form above the
load waterline, with a slight rake forward to minimize the effect of a collision, and to
overcome the appearance of “falling aft” at the head, which was the usual look
of a completely vertical stem.
The stem was fabricated from rolled bar of rectangular section in five
segments totaling 7¼ tons. A 3½-ton, cast-steel forefoot of hollow section at the lower
end connected the stem to the keel plate. These sections were connected to one another
through 2'-6" long scarfs using flush rivets. Fabrication of the stem in segments
eliminated many handling and construction difficulties and reduced the costs of repairs in
the event of damage.
. . (continued) |
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| Image above, C Deck Rudder
Steadiment - The aft end of the Shelter Deck (C) showing the plating and framing
in way of the rudder steadiment. Illustration
by Bruce Beveridge based on original H&W Shelter Deck Iron plan. |
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Stern frame
- The function of the stern frame was to provide support to the rudder, center shaft boss
and tail end shaft, and to frame the aperture in which the center propeller revolved. The
principal parts of the stern frame were an after or rudder post (the “stern
post”) which held the gudgeons and bushings in which the rudder pintles rode, and a
propeller post which incorporated an enlarged or “bossed” area through which the
center tail shaft and stern tube passed to carry the center propeller. The castings
forming Titanic’s stern frame were of massive construction. The size and
strength of these castings were necessitated not only by the huge size of the vessel, but
by the enormous stresses to be borne by these castings. With the lower portion of the
rudder post standing free of the hull, it had to be strong enough to withstand both the
weight and the side forces generated by the rudder. . . (continued) |
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Rudder - The rudder is that part of
the vessel which controls the direction of her movements when afloat and in motion. In its
simplest form, a rudder consists of a wide, flat blade and a vertical shaft or stock by
which this blade is turned so as to steer the ship.
Rudders are either of the “semi-balanced” or “unbalanced”
type. A semi-balanced rudder has part of the blade extended forward of the rudder stock,
while an unbalanced rudder has all of its effective area aft of the stock. A semi-balanced
rudder requires a smaller steering engine than an unbalanced rudder, as the water pressure
on the forward edge tends to partially counterbalance the forces acting against the after
edge. About 25% of the total area of the rudder is placed in the forward balancing
section. Semi-balanced rudders were generally used on warships as they give maximum
maneuvering ability without requiring excessively powerful steering gear. Quite often the
term “balanced rudder” is used instead of “semi-balanced rudder.” The
term “semi-balanced” is used in this text as no rudder is truly balanced
throughout the entire turning angle. The unbalanced rudder was used in many ocean liners
of the time. In the case of the Olympic-class ships, the design of the stern and
the arrangement of the propellers necessitated the adoption of this type of rudder . . . (continued) |
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Other topics in this chapter: Boss castings |
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