IN fact the ship was recorded going 21 knots on all ahead full. Reversing engines at this speed means that the propellers cavitated. Cavitation is where air gets sucked in by the propellers causing a significant decrease in thrust or pull.So at 21 knots a ship that wweights about 45 thousand tons being ordered to reverse full will definately cavitate. The ship had 3 propellers not 2 not 1. 3 propellers, 1 main 2 auxillary or support propellers. The ship had a different engine for each prop (as do most cruisers) The main prop did not have a revers transmission. The 2 auxillary did. NOW then the 2 auxillary propellers were 2/3 the size of the main propeller. When the order went out for revese the main propeller stoped turning. In the order also said hard to port (left) witch means one auxillary propeller was to slow its reverse speed and let the other go full reverse. THE DESIGN FLAW---- the auxillary propellers where too small. When the props where thrown in reverse one was doing more work than the other witch made the ship tilt to the right a couple degrees and made the propeller doing full reverse cavitate. Witch in fact did not help the turning process at all. ANOTHER DESIGN FLAW---- was the rudder, it was simply too small for the ship (im not gonna get into details). heres a visual of whitch direction each propeller was pulling\pushing.
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I have studied trust in seacraft and propulsion and ballistics in avaition for 8 years this is my best explination of what happened