Torpedo Running Depth Fit for USS Liberty, not El Quseir
K. J. Halliwell  (November 14, 2004 -- Revised March 5, 2013)

The torpedo blast-hole, on the starboard side of USS Liberty, was about two-thirds distance back from the bow-point to the front edge of the superstructure, and extended from the bottom of the second deck to the bottom of the forth (i.e., bottom) deck.   It was a significant attack damage feature and well-documented via many photographs taken from different viewpoints.

Upon close inspection of the photographic images, you can see the hull's horizontal weld-lines.  These weld-lines are placed identically on all Victory Ship hulls (USS Liberty was a converted Victory Ship).  Thus, they provide critical points of reference for analytically purposes.
By treating the photographic images as perspective drawings and applying basic graphic analysis techniques, the blast-hole's dimensions and center (i.e., the approximate point where the torpedo hit) were determined.  To validate and enhance the photographic analysis work, actual blueprints of a Victory Ship hull were used to obtain dimensional and structural data.
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The analysis revealed (as shown below) that the blast-hole appeared somewhat oval-shaped with a short "smoke stack" sitting on top.  The "smoke stack" or vertical tear was about 8 feet high.  The main hole was at least 33 feet wide and 16 feet high (24 feet high when including the vertical tear hole).
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In photographic images, it is clear that the bottom edge of the blast-hole appears flattened.  This was likely due to the strength of the double-bottomed hull resisting and limiting blast force damage.  The vertical tear, at the top of blast-hole, was likely due to a combination of the blast-force's propagation or expansion upward, and the collapse of major frame number 58.  (The "path of least resistance" expansion of the blast force would have resulted in a large portion of the blast's intense force rapidly projecting upward, along the side of the ship, likely contributing to production of the vertical tear, and finally resulting in a large, vertical water spray in the air.)

In the images above, the blast-force is idealistically depicted as a perfect circular zone, with a diameter determined by the horizontal edges and curvature of the blast-hole.  The center of this circular blast-force zone is the approximate focus or center of the torpedo blast -- marking where the torpedo hit and its running level.  As you can see, the vertical centerline appears very near one of the ship's major vertical frames or ribs.  (There are claims that the torpedo hit exactly on major frame number 58, but upon further analysis of the strike point, it appears that it hit slightly forward of major frame number 58.)  The horizontal centerline appears about 12 feet below USS Liberty's estimated operating draft level (21 feet, 6 inches) during the attack. In other words, the torpedo's running depth was about 12 feet (about 4 meters) below the water's surface.

Using a blueprint of one of USS Liberty's major frames, with operating draft level and torpedo running depth added, a comparison was made with an outline of El Quseir's hull sitting at various draft levels.  As you can see below, the comparison revealed the torpedo's running depth was too low to reliably strike El Quseir's hull.  If she carried a full load of fuel and cargo (i.e., riding at her maximum 14 feet draft level), then the torpedo would have likely hit near the bottom of her hull side, but if she carried less than a full load of fuel and cargo (i.e., riding a few feet less than her maximum draft), then the torpedo would have likely missed.

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Thus, to ensure striking the side of El Quseir's hull one would expect the torpedo's running depth to be no greater than about 7 feet (about 2 meters) or half El Quseir's maximum draft.[1]  With the torpedo's running depth at about 12 feet, it was slightly more than half of USS Liberty's maximum draft (22 feet, 6 inches) and slightly less than El Quseir's maximum draft.[2]  In other words, the torpedo's running depth was well-suited to strike the side of USS Liberty's Victory Ship hull and not El Quseir's hull -- as depicted in the image below.[3][4]

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