Last week, we looked at the visible outer part of the ship’s hull, her plating, castings, forgings, and rivets. We also discussed the way in which the individual plates were assembled. The plates, which formed Titanic’s outer skin, would not, however, have anything to attach to if not for the frames.
The frames inside a ship’s hull are not visible in exterior photographs and are only somewhat evident in photographs of the interior. They are like the skeleton in a human body, giving a ship its overall shape and also providing strength and internal structure. Ships are divided by transverse frames spaced at intervals from the stem to the stern.
While various numbering schemes for frames can be used, Titanic’s frames were numbered from amidships, with the exact middle frame left unnumbered. Each frame radiating from that was numbered sequentially and denoted as either forward (“F”) or aft (“A”) of the midship frame. Thus, the frame directly forward of amidships was “1F” and the one directly aft was “1A.” At the forward perpendicular, the forward-most frame was 156F. At the front of the sternpost was the aftmost frame, number 148A.
The transverse frames were spaced differently in different areas, closer together at the bow (as close as 24 inches) and stern (as close as 27 inches) and further apart amidships (up to 36 inches). The closer spacing was due to the ship’s experiencing higher stresses on the hull at the ends.
The frames ran from the tank top above the cellular double bottom (which formed their floor) to B deck, including the forecastle and poop decks. This formed the “box girder” of the ship’s hull, a hull form that proved incredibly strong and resistant to the high stresses of the North Atlantic routes. Each frame was composed initially of a straight steel bar that was then bent to the needed shape. The frames, once attached to the ship’s bottom, were joined by beams at each deck level. These were supported vertically by pillars and longitudinally by girders. Stringer plates were also fitted in specific areas to increase strength, with these running horizontally along the frames where the vertical distance between beams was larger (as in the holds, boiler rooms, and engine spaces). Stringers were also fitted at B-deck level for added strength.
Framing of the ship would be completed before plating, as the plates would attach to the frames. Frames would subsequently be used to identify locations on the ship (you can often see a frame referenced in studies of the damage by the iceberg, for example). With the beams and pillars giving a ship the basics of its internal form, rooms and interior spaces could be constructed around them when the time came.
Next Week: Making Titanic Watertight
Written By: Nick DeWitt
Photo Credit: Titanic Connections Archive
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