The concept of open computational systems represents physical and dynamic environments populated with self-organizing networks of cognitive entities, i.e., open systems of human users and software technology continuously deliberating in a physical environment. The foremost challenge with this class of systems is that of automated sustainability, i.e., online assertion of systemic qualities. To that end, we introduce the application domain of trustworthy and sustainable operations in marine environments and our experience of applicable models in experimenting with quality of service in network-centric warfare. Finally, we conclude the paper with a discussion regarding challenges in the domain of open computational systems.