Mk37 definitely is swim out. I have had some success in launching and/or letting the torps run beneath a strong layer before activating them - torps are slower and make less noise when inactivated, and the layer may hide them.
I'm not sure if the layer is also modeled to conduit sound when the sound source is directly in the layer, or if that even is a thing in real life, but, I've also seen ships react to my transients at great ranges when I've launched in the layer when the layer has been shallow. It could have been towed array or helicopter's hydrophone dipping into or below the layer.
Pay attention to ambient noise level too, it actually seems to be very important. I've managed to sneak Mk37s as close as 1 k yrd from an escort in a storm even without a layer, then flash radar to make him turn, speed up and run blind into the torp.
