The Squirt is a small cargo ship that is good for carrying water or batteries. It is based on an earlier design, The Starfish, which had only one hub. It has a capacity of 24 units of cargo for short trips. However it typically only carries 20 units of cargo and uses the other space for additional life support.
The engines on the ATV face opposite directions enabling The Squirt to accelerate and decelerate without having to rotate. It has very good control forward and back, but moving side to side introduces rotation. This is managable because the docking ports are located on the front and back limiting the need for side to side motion.
One ATV can also be detatched and used as a shuttle to transport cargo to stations. This eliminates the possiblity of The Squirt's momentum bumping the station out of position when docking.
After construction, The Squirt was quickly put into service delivering water to several stations where the Oxygen gardens were begining to turn brown from a drought.