Torpedo search settings and seeking behaviour with layer

[speed150mph]

So I was playing a mission yesterday in a kilo. I had a strong layer at 140m and was stalking a Walrus class submarine that was sitting above it. This senario brought up a question.

Is there any way in dw (I have RA mod) that I could fire my torpedo so that it would run below the layer, and then when enabled, would pop up above the layer and take the enemy sub by suprise, giving him less time to evade and me more time to move out of the way of any snap shot down the bearing.

Thanks