[Farmer Dean]

I think you’re right about the no evasive zig-zagging,assuming no subs turned out to be a costly mistake.If only there had been one destroyer with her-they could have saved a whole lot of lives.

[mainepatsfan]

As I recall the Japanese sub also carried a few kamikaze torpedo pilots but the commander decided he didn’t need to make use of them because the shooting conditions were so good.

[Tallguy]

At McVay's courtmartial the Japanese skipper was asked if it would have made a difference if the Indianapolis would have been zig-zagging. He said 'No'.

Some surface ships, like this cruiser, had such speed that it was felt that zig zagging was unnecessary under certain conditions. IIRC, the cruiser was running in & out of storm fronts & so ceased zig zagging for safety reasons -- I could be wrong on that point.

Submerged submarines were generally too slow to get into firing position once detecting such a ship unless they got lucky. OTOH, if the sub was running surfaced, where it would be faster, the firing solution would be easier.

All that being said, Japanese I-boats were some of the fastest subs around in WW2. They were designed to keep pace with our battleline and attrite it prior to a big gun battle.