Abstract: A system for enhancing control of an underwater vehicle, and providing a quick change modular payload section includes a motor configured to rotate an internally threaded member threadingly engaged with a threaded rod. Rotating the member creates linear motion of the threaded rod. A control rod connected to the threaded rod provides movement of a rudder or fin. The threaded rod and member are configured with threads having a fine pitch which maintains a stable position of the fins without needing to supply power to the motor for adjustments. The modular payload arrangement includes a bulkhead ring having L-shaped recesses that receive fasteners disposed on a central body section. The payload section may be fastened to the vehicle by pressing the payload section onto the central body such that the fasteners align with the recesses and turning the payload section to secure the payload section.