There is another way to remove convoy escort without sinking them, May be bug or something.

Get the excorts chasing you, I sink single freighter or oescort on side. Then evade escorts and once they calm down most of them will leave the convoy. Usually one escort keeps with the convoy and the rest of them just sail away.

I don't go for sinking warships unless I see a big advantage in sinking all the merchands, so if only 1 destroyer protects part of the merchands in my range I will go for a T5 to sink it. Or I will use T5 as a last ressort for a horde of destroyers going after me to give me a good evasion line.
Oilers and merchands are always worth more for the war effort compared to sinking cheap warships, and it's a good thing that the game doesn't give you big rewards for it.

引用自 japp_02：

I don't go for sinking warships unless I see a big advantage in sinking all the merchands, so if only 1 destroyer protects part of the merchands in my range I will go for a T5 to sink it. Or I will use T5 as a last ressort for a horde of destroyers going after me to give me a good evasion line.
Oilers and merchands are always worth more for the war effort compared to sinking cheap warships, and it's a good thing that the game doesn't give you big rewards for it.

My idea came from killing them easily while i was chasing a medium sized convoy.
7 escorts 15 merchants.

Takes literally few minutes since they are rushing towards your location.
So you don't have to chase them down.

After the destroyers and corvettes are dead you get free kills on the merchants.
They can't out run you since you are double their speed plus hydrophone and have an idea of their course.

Once the defenders are dead you can kill the convoy.

If you don't deal with the defenders, each time you take a pot shot at somebody you also need to avoid defenders.

i mean i've also powered through a convoy at 100m deep and then shotgun some T5s at merchants, but i've never got more than 10 ish including destroyers.

Which isn't horrible just ..they will still swarm you so your T5s will still target them.
But then will be at random.
Rather than being your decision.

You don't even have to kill the warships, just take out their engines.

I have a couple of saves i could use to see if this is as effective as it was in the fight i came up with the idea.

Definitely unrealistic, I believe the maximum depth a U-boat was capable of firing torpedoes was 50m. Of course even then you'd be using considerably more compressed air to fire them through the extra pressure. I imagine such a tactic would be impossible in real life or it would've been done in real engagements.