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To: WhiskeyX

My mother, who grew up in Hawaii and went through Pearl Harbor as a high school senior, ended up leaving Hawaii on the Lurline to go to college on the Mainland right after high school graduation, where she was for the “duration.” A lot of young people were evacuated from the islands because of the fear of Japanese invasion (if their families could afford it).

My Mom recounts how the Lurline had been repainted in naval camouflage and refitted as a troop ship, and made the trip to San Francisco constantly zig-zagging at irregular intervals in order to try to avoid torpedoes that might be fired at her by Japanese submarines.

She ended up not returning home until 1946.


3 posted on 12/08/2015 9:32:59 PM PST by kaehurowing
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To: kaehurowing

Interesting personal note, thanks. BTW, zig-zagging was intended to throw off pursuing submarines, not torpedoes. A slower ship (say a submerged sub) can intercept a faster ship if their courses can be made to intersect. The pursuer maintains a course in which his line of sight, measured off the bow, to the prey is constant. If line of sight between the pursuer’s course and the prey is opening (getting wider) the pursuer will pass in front of his intended prey, if it is opening, he will pass astern, if it is constant, they are on an intercept course. (In peace time navigators use the same logic to avoid collisions.) Constant line of sight produces the most efficient intercept course when both vessels are moving at constant speed.

Nowadays it is generally agreed that zig-zagging is worse than useless because you are as likely to zig into range of submarine as zag away, and overall it makes a longer course, leaving you exposed to the enemy for a longer time.


7 posted on 12/09/2015 3:50:21 AM PST by Lonesome in Massachussets (Men need a reason to shop. Women need a place.)
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