I got to thinking. You wouldn't have to have another campaign layer for AI boats.
airplanes have airbases as spawn points... the AI BDU detects whether or not you are within range of one of these air bases, and it decides based on a % chance whether or not to send air units to assist you.
why not just have a bunch of hidden AI U-boat spawn points?
you could scatter perhaps 20 or 30 AI U-boat spawn points throughout the North Atlantic, and perhaps 4 or 5 in the south Atlantic and so on.
The spawn radius of each of these AI U-boat spawn points would be something like 150nm or 200nm or something of the sort.
if you are within this spawn radius and you send in a contact report, the AI BDU would then decide based on a % chance how many AI U-boats would theoretically be occupying that radius... then it would decide how many would be responding to your contact report.
The AI U-boats initialized for response to your contact report would then spawn, and set maximum speed toward an intercept point which would be based on the speed and course provided by you in your contact report.
BDU would then provide periodic updates, "U-42 and U-96 have been redirected to assist you, they expect contact in 10 hours."
BDU would then update you on the progress of their arrival on attack stations "U-42 and U-96 have provided tactical updates and will arrive to assist in attack in 5 hours."
and finally "All boats are assuming attack positions, begin attack at 0600 GMT"
to prevent AI U-boats persuing convoys to the ends of the earth and/or attacking until they are killed... i think that a limitation should be placed on AI U-Boats that they will break off their attack and leave the area when one of three conditions are met
1. they have fired 5 torpedoes.
2. they have expended half of their battery life.
3. they have suffered some form of damage.
Finally, for increased immersion, when a contact report is received by the player (as is so often the case) BdU should direct the player to break off of his current duties and respond to the contact report, when the player arrives he may or may not see other u-boats preparing to attack... however there should come a message from BDU "Boats are assuming attack positions, begin attack at 1800 GMT"
this way it is not always the player initiating the wolf pack tactic.
the pro of doing this
* it is more historically accurate as to real life u-boat operations and BDU micromanagement... hard core players would greatly appreciate the added realism
the con of doing this
* many players like the idea of cruising around having the world to themselves... they might not enjoy being micromanaged.
there should be a realism option to allow for the inclusion of AI wolfpacks... in other words if the player selects "No AI U-boats" it will just disable the U-boat spawn points.
in summation
1. Scatter AI U-Boat spawn points around the map
2. When the player sends a contact report for a convoy (not a single ship) the AI BDU engine will determine whether or not AI U-boat spawn criteria are met
3. if AI U-boat spawn criteria are met... x number of U-boats will be directed to join you in your attack and will head toward an intercept point at max speed.
4. the player will have to hold off on his attack and provide updates so that the "intercept point" of the AI U-boats can be further updated
5. so as to prevent the player from Time skipping through his own attack, BDU will provide updates as to the position of incoming u-boats at 24 hour, 12 hour, 10 hour, 5 hour, 3 2 and 1 hour intervals.
6. finally, when all boats are within visual distance of the convoy, BDU will direct the attack to commence at some later time... this gives the player a time frame to get established into position and prepare to fire his torpedoes - and prevents the AI from attacking before the player is ready... this keeps all hell from breaking lose before you are even in position to attack.
7. When an AI boat has 1. fired 5 torpedoes, 2. used up half of their battery or 3. suffered damage... the AI u-boat will break contact and head it's own separate random direction.
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