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Introduction
- The frame of a ship may be considered the skeleton of the vessel. Next to the keel, the
transverse frames are the most fundamental part of a ship’s structure; extending to
the top of the vessel in a transverse plane, they define the shape of the hull at the
point they are fitted and provide the place of attachment for all of the shell plating.
Frames could be formed from nearly any of the rolled bar shapes available, although the
shapes most commonly employed in framing ships of riveted construction were those of
channel, plain angle, bulb-angle, T-bar and T-bulb-bar section. Frames formed from any of
these bars alone were referred to as “solid frames.” Frames constructed by
riveting together any of these sections in combination with one another, and also in
combination with steel plates, were called “built frames.” The two most common
forms of built frames were the angle frame and reverse frame, and the . . . (continued) |
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Image above, Midship Section (Full) - The midship section of Olympic
and Titanic. Unlike the original midship section provided in Chapter 1, this plan
shows the fittings of the ships as completed, and is an actual midship section in that it
is the view as if the ship were cut in half midway along her length. All of the major
components are illustrated, including the joggled angle bars that attached the bottom
shell plating to the floors, the beam heights of the decks, pillars, web frames and other
structural members. Illustration, Bruce
Beveridge based on original H&W Midship Section.
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Vertical transverse frames - The two
uppermost decks forming Titanic’s superstructure were built to ensure a high
degree of rigidity. At the sides they were supported on built-up frames in line with the
hull frames, but at a much wider interval of every third frame. The deckhouses were
specially stiffened by channel section steel fitted to the framework, and where the public
rooms pierced the decks, as on the Boat Deck, heavy brackets were introduced to increase
the resistance to racking forces when the ship was steaming through a heavy seaway.
The frames were manufactured as straight bars cut to rough oversized length.
They were bent to the required shape and then trimmed to proper size in the shipyard by
the frame benders. The initial step in preparing the frame bars was to punch all the
necessary rivet holes before it was bent to its required shape. The rivets connecting the
frames to the reverse frames were spaced at a pitch of 6 diameters apart; those connecting
the frame bars to the shell were spaced from as little as 4 diameters to as great as 7
diameters apart, depending on the size and location of these rivets and the thickness of
the materials being connected. . . (continued) |
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Fabrication
of frame bars - Beveling of frame bars could be done by hand or machine. The
amount of bevel was determined by the loftsman from a bevel board. In machine beveling,
the bar was beveled from the heel. The frame was drawn out of the furnace after it had
reached full heat. One end was pinned to the end of the set iron and the other was worked
round to its shape, pinned down, and kept in position on the blocks by the use of iron
dogs and pins. An important concern in bending angle bars was that during cooling more
contraction took place at the heel of the bar, where the material was thickest, than
anywhere else. This resulted in a bar which was bent from the heel (as was the frame bar)
somewhat straightening itself as it cooled, thereby reducing the curvature. The frame
benders, guided solely by experience, gave more curvature to the frame than the scrive
board indicated when the bar was heated so that it would achieve the desired shape as it
contracted during cooling . . . (continued) |
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Other topics in this chapter: Spacing and
identification of frames - Frames in way of the double bottom - Deep frames - Web frames -
Beams - Pillars - Columns and stanchions in way of engine and boiler rooms - Erecting of
the frames |
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