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Updated: Nov. 20th, 2007

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The Engineer / Author's Collection
Rudder Head of Olympic in the Lathe.
The Engineer /
Author’s collection
The Engineer / Author's Collection
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

Illustration by Bruce Beveridge based on original H&W Shelter Deck Iron plan.

   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 7 tons. A 3-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)

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.

   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)


   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)


Other topics in this chapter: Boss castings

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