The tactics adopted by escorts to track down a sub

[Pascal]

I'm using Mod IRAI_0_0_42, and I'm wondering about the escorts' tactics when a convoy of merchant ships is attacked : you can see that all the escorts abandon the convoy's surveillance to come and hunt down the sub ... So we find ourselves surrounded by a dozen or so boats. It seems to me that logic would dictate that a maximum of 3 escorts should hunt down the sub, not the horde!