Convoy escort have two great advantages over "real" escorts:
(1) They have no range limitation and protect the whole sea lane the convoy is passing through.
(2) They are invisible, so the enemy cannot figure out how well your convoys are protected without actually attacking them.
You will need a significant amount to cover your convoys, but they work really well against submarines if used in adequate numbers, forcing the enemy to form wolfrudel-packs that are easier to spot and fight.
In genereal escorts are good against enemies that use small stacks for raiding, such as single, double or triple subs, sole BCs and small DD forces.
Escorts cannot, however, protect you against larger fleets and airpower - if the enemy has some decent sized sea units that threaten your convoys, you will need to mobilize your fleet to counter him.
Building some escorts before the war is never a bad idea. They improve sea lane protection and free other naval units you can use elsewhere until significant danger for your convoy turns up.
So, for example, you don't have to sortie two hunter-killer-groups against german subs in the atlantic if you have adequate escort protection.
(1) They have no range limitation and protect the whole sea lane the convoy is passing through.
(2) They are invisible, so the enemy cannot figure out how well your convoys are protected without actually attacking them.
You will need a significant amount to cover your convoys, but they work really well against submarines if used in adequate numbers, forcing the enemy to form wolfrudel-packs that are easier to spot and fight.
In genereal escorts are good against enemies that use small stacks for raiding, such as single, double or triple subs, sole BCs and small DD forces.
Escorts cannot, however, protect you against larger fleets and airpower - if the enemy has some decent sized sea units that threaten your convoys, you will need to mobilize your fleet to counter him.
Building some escorts before the war is never a bad idea. They improve sea lane protection and free other naval units you can use elsewhere until significant danger for your convoy turns up.
So, for example, you don't have to sortie two hunter-killer-groups against german subs in the atlantic if you have adequate escort protection.