The Construction Ship is a good builder in terms of build power and speed. Even a single one of these assisting the lab almost doubles its output of units provided that you have the resources. On top of Commander’s build list they're able to produce more advanced T1 defences like the Floating Heavy Laser Turret and give access to T2 Shipyard. It adds 50 to your metal and energy storage capability
Use them for assisting the lab and quickly expanding, claiming the metal spots with underwater metal extractors.