Hi sidlslotm,
the closest I found for that while I was working in the British Campaign is UPC.cfg in the DATA/Cfg folder
Code:
[MissionManager]
RenownValuesUS=-250,-100,0,750,2500,9000
RenownValuesGE=-250,-100,0,750,2500,9000
MinimumDaysInBaseUS=5
MinimumDaysInBaseGE=28
AcceptableDamageUS=25
AcceptableDamageGE=25
RankDaysUS=180,365
RankPatrolsUS=5,5
RankPatrolsRatingsUS=1,1
RankCampaignRatingsUS=1,1
RankDaysGE=180,240,540,720
RankPatrolsGE=3,5,7,5
RankPatrolsRatingsGE=1,1,2,2
RankCampaignRatingsGE=1,1,2,2
This allows to stablish the minimum number of days in base. I guess that damage to your boat or rest needed for the crew may increase the number of days.
Hope it is what you're looking for.