Fenris, still, isn't it just as easy, or maybe easier, to open both tubes, aim at one target, fire, then aim at the other, and fire? If both targets have the same speed, and are equidistant from your boat, then you don't need to change TDC settings - just shoot. I've never seen the benefit of the spread, personally, except for extreme long shots (i.e., late war). By then you're guessing range so badly that perhaps the spread gives you a simple way to fire a fan without shifting the periscope around.
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