I've collected some figures from various threads here in the forums. Most of them are from new posts,
because they are more recent, while the others were dug up from the old forums. Recent patches may have
changed these caps as well so feel free to contest anything listed here, and urge others to contribute their
own findings. Thank you.

Sailor True Ability Caps
Potential = no data (guidelines, ss air refill, sonar view range, etc)
Accuracy = 1,600,000 ~ 1,950,000 (shell accuracy)
Reloading = 2,500,000 ~ 2,700,000 (naval gun/AA reload rate)
Torpedo = 1,007,000 ~ 1,050,000 (reload speed)
AAW = disabled
Repair = 35,000,000 ~ 43,000,000, see Other Caps below
Restore = capped, see Other Caps below
Engine = not capped, see Other Caps below
Aircraft = not capped, highest true value rated at 4,450,000 (aircraft sight)
Fighter = not capped, highest true value rated at 4,400,000 (aircraft AA)
Bomber = no data (aircraft durability)

Other Caps
Repair rate (from Repair sailor ability) = 250 ~ 280DP/s, higher values are extremely hard to achieve
Burn rate (from Repair sailor ability) = capped, 25DP/s, higher Repair ability, higher burn rate
Soft Defense (from crew size, Restore sailor ability) = capped, 900
Over Heat time(from Engine sailor ability)= not capped, use as many Engineers as you want to extend OH time
Air Refill time (from Planesman sailor) = capped, still unknown

Revision history:

10/22/11 - Torpedo Cap updated, patch 1.330