Remember the mnemonic: ITEM CAR
source: thegamer.com
Formula for getting perfect IVs for your freightermons:
base stat total = (sum of current stats) - (sum of stats from traits) - (# of rank ups * 6)
Base stats can be anywhere from -5 to 14. If looking for new frigates, 14 is the perfect number to go for.
You can determine the number of expeditions per rank up using this table:
| Rank | # of Expeditions |
|---|---|
| 1 | 4 |
| 2 | 8 |
| 3 | 15 |
| 4 | 25 |
| 5 | 30 |
| 6 | 35 |
| 7 | 40 |
| 8 | 45 |
| 9 | 50 |
| 10 | 55 |
So a frigate which has gone on 27 expeditions should be at rank 4.