There were timed fuzes for both German 37mm and Bofors 40mm, but I can't imagine these were ever used on submarines, as the process for setting such a fuze would be impractical on a sub deck.
They did, however, self-destruct, typically when the tracer burned out. For example, the 37mm c/30 ammo had a 12 second tracer, so it would likely be very far away before self-destructing.
The self-destruct range and effect can be adjusted in the shells.sim file.
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-AKD
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