Custom rules: Single board Naval Fog of War and modified submarine combat(by My Name is Watt/Michael Withstand).
The rules are as follows 1. Separate submarines combat from combat dealing only with surface combatants. Thus surprise strike changes meaning to: to be able to dive away out of battle before enemy able to strike
2. Surface combatants are thought to have formed surface action group while submarines are never part of surface action group and are never thought to form any submarine group (submarines are thought to operate independently or loose pack). In effect this means submarine will have to decide meeting individually or be met individually while surface action group only roll a single die for the whole group when rolling for meeting both if attacking or defending.
3. When surface combatants want to engage or start combat with enemy surface combatants they first will have to find each other. Without the presence of ATTACKING fighters(carrier borne or land based) they will meet either roll 1-3 or 4-6(Each side roll one die and if both roll 1-3 or 4-6 then combat occurs as usual). In the presence of ATTACKING fighter both side meet 1-4 or 3-6 (So that 3 or 4 will always result in combat). Otherwise no combat occurs and both enemies ended up sharing the same seazone
4. In the presence of mixed submarine and surface combatant in battle the ATTACKING side choose whether to engage the whole surface combatant AND air combatants first OR sub-surface combatants first with either group of type of their sub surface force or surface force.
5. When attacking enemy submarine with surface and air combatants(surface action group) CHECK if you have DESTROYER Both side still role a single die to decide f both sides meet in combat(Note that rolling for meeting occurs for each number of defending submarine as sub never operate together) (roll 1-3 or 4-6)/(roll 1-4/3-6 in the presence of attacking fighter). If both sides meet check whether the ATTACKING side has destroyer, if so for each destroyer roll a die for every enemy submarine that are defending and count roll 1-3 as success to simulate having successfully detected each submarine. For each defending submarine that are successfully detected by a minimum single attacking destroyer put it on the battle board as defending submarine with rules as stipulated in the rule book with regard that destroyer is present so that these lose all of their special abilities. For each defending submarine that meets but failed to be detected, it now has the ability to make surprise attack with an atack value of 2(Put it on the battleboard as attacking if you need to even though the subs are defending) Having rolled for a single surprise attack these submarine MAY disengage from battle WIHTOUT giving the attacking forces a chance to attack them. I any chooses to remain in battle for the next round put them back to the defending side of the battle board and the original rule applies for subsequent battle round.
If there was no destroyer present the surface action group not equipped with attacking air fighter only able to detect each sub on roll of 1. If attacking surface action group is complemented with fighter it is able to detect each sub on roll 1-2. This check is also done when submarines are attacking surface action group not escorted with destroyer (detection roll is done on each attacking submarine). Success on detection roll in this case means the sub loses its surprise strike ability and is obliged to be put on the battle board with the original rule except that it now has lost it surprise strike ability but may choose to dive away out of battle(from submersible ability)
6. When submarine force are attacking enemy surface action group CHECK if the defending force is complemented with destroyer forces Both side still role a single die to decide f both sides meet in combat(Note that rolling for meeting occurs for each number of attacking submarine as sub never operate together) (success when both roll 1-3 or 4-6 since there's NO attacking fighter as attacking fighter is thought as part of surface action group). If any of these attacking sub manage to meet their enemy defending surface action group CHECK if the defending force has destroyer in them. For each attacking sub that manages to meet the defending surface action group it must successfully evade EACH defending destroyer by rolling 1-3. If the attacking sub manages to meet and evade ALL defending destroyer they can achieve surprise strike and then dive deep out of battle before enemy able to attack them. If these didn't want to dive deep put them on the board as atatcking sub and original rules applies. If however if any of the attacking sub that manages to meet their enemy yet fail to evade JUST ONE defending enemy destroyer(fail by rolling 4-6 instead 1-3) then that sub CANNOT achieve surprise strike, put on the battle board and original rule applies.
7. When submarine are atacking enemy surface action group WITHOUT the presence of any defending destroyer first both sides roll for meeting. Note each attacking sub roll one die but defending surface action group only roll a single die for the whole surface action group(sucess on 1-3 as there's no attacking fighter as any attacking fighter is considered to be part with surface action group and never part of submarine) If these successfully meet, the DEFENDING force roll a die for each attacking sub that successfully meets them. Count success on 1 in the non presence of defending fighter plane or 1-2 in the presence of defending fighter plane. If the roll was a failure then that particular sub achieve surprise strike and may dive deep out of battle before the defending surface action group able to fire on them. If they decided not to flee after rolling for surprise attack conduct battle as stipulated in the rule book for the next round. If the defending surface action group successfully detected particular attacking sub, that sub cannot achieve surprise strike and put on battle board and original rule applies. These however still can dive deep out of battle if they choose so before rolling for attack roll.
8. When combat is between sub VS sub, in order for both side to meet both side must roll 1 FOR each Defending submarine FOR each attacking submarine to decide meeting and whether combat occurs. On the battle board there's no more at one time than 1 attacking submarine and 1 defending submarine (combat between sub is always a duel). Thus resolve sub Vs Sub battle 1 Vs 1 at one time until all met by the specific attacking sub has been attacked or sunk or the particular attacking sub retreats or dives deep.
9. Surface action group that's part of amphibious assault when when assulting beaches(doing amphibious assault) are always found out by defending naval forces in that seazone. There's no need for fog of war or meeting roll in this case
10. Any sub which successfully able to achieve surprise strike able to pick their prey before rolling for attack.
11. There no need to roll for meeting if the defending enemy consists of transport only. They are automatically destroyed when not defended as in the original rule
12. Any attempt can be made to try to bypass enemy surface action group but can only player can only do so after rolling meeting roll and failing to meet the enemy surface group(or successfully evading them) in the combat phase move and may continue either in combat move if it ends in hostile sea zone or amphibious assault or continue in noncombat move if it ends in friendly sea zone.