SH3 Commander is a wonderful addition to SH3.
It has options that allow some of the following..
Random Merchant skins based on time period(Merchant Variety Pack)
Simulates real career length
Simuate of realistic crew transfers(you'll loose crew menmbers to various reasons)
Options for what fatigue model you want to use
Adjust the fogginess of the water to your own taste
Wave height adjustments
Deck Gun reload time options
And alot more...
You can get it here and check it out..
http://www.beerymod.com/SH3Cmdr23.exe