I think you are both right, if you remember as CB says we had problems on SH2 similar to this, caused by certain ships either too close or going the wrong speed etc.
It just could be that you hit a certain ship that caused the others to evade/avoid each other and they couldn't get back to an organised state again, perhaps IF you had hit a different ship it may not have happened as bad as it did.
I've had the odd convoy where I've seen certain ships start to evade and then gone in the opposite direction, I've not waited long enough to see if they ever re-join the convoy again, I've either sank them or got out of there.
(CB do you remember the Treeburst threads on this in SH2?)
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