Rank Ship is a low-level shuttle that you can always buy. This is so that if you want to store a good ship and trade down (or trade one in) you don't have to wait to find a Starport selling a shuttle or a fighter.
If you do not want to buy Shuttles than it is useless.
Dry Dock requires Rank. Once you have Rank you can use Dry Dock. When you purchase a ship you can Trade In Current Ship or Purchase New Ship. If you Purchase New it goes into the Dry Dock.
Then, inside the Military Base you can use Dry Dock to switch ships. You can install different upgrades and have different cargo on each ship in Dry Dock.
The new v2.8.3 edition fixes HTC Wildfire and HTC Tatoo issues. Sorry about htat.
The Captain now controls how many people go on an Expedition or Harvesting!