As Autonomous Underwater Vehicles (AUVs) become more technically capable and economically feasible, they are being increasingly used in a great many areas of defence, commercial and environmental applications. These applications are tending towards using independent, autonomous, ad-hoc, collaborative behaviour of teams or fleets of these AUV platforms. This convergence of research experiences in the Underwater Acoustic Network (UAN) and Mobile Ad-hoc Network (MANET) fields, along with the increasing Level of Automation (LOA) of such platforms, creates unique challenges to secure the operation and communication of these networks. The question of security and reliability of operation in networked systems has usually been resolved by having a centralised coordinating agent to manage shared secrets and monitor for misbehaviour. However, in the sparse, noisy and constrained communications environment of UANs, the communications overheads and single-point-of-failure risk of this model is challenged (particularly when faced with capable attackers). As such, more lightweight, distributed, experience based systems of “Trust” have been proposed to dynamically model and evaluate the “trustworthiness” of nodes within a MANET across the network to prevent or isolate the impact of malicious, selfish, or faulty misbehaviour. Previously, these models have monitored actions purely within the communications domain. Moreover, the vast majority rely on only one type of observation (metric) to evaluate trust; successful packet forwarding. In these cases, motivated actors may use this limited scope of observation to either perform unfairly without repercussions in other domains/metrics, or to make another, fair, node appear to be operating unfairly. This thesis is primarily concerned with the use of terrestrial-MANET trust frameworks to the UAN space. Considering the massive theoretical and practical difference in the communications environment, these frameworks must be reassessed for suitability to the marine realm. We find that current single-metric Trust Management Frameworks (TMFs) do not perform well in a best-case scaling of the marine network, due to sparse and noisy observation metrics, and while basic multi-metric communications-only frameworks perform better than their single-metric forms, this performance is still not at a reliable level. We propose, demonstrate (through simulation) and integrate the use of physical observational metrics for trust assessment, in tandem with metrics from the communications realm, improving the safety, security, reliability and integrity of autonomous UANs. Three main novelties are demonstrated in this work: Trust evaluation using metrics from the physical domain (movement/distribution/etc.), demonstration of the failings of Communications-based Trust evaluation in sparse, noisy, delayful and non-linear UAN environments, and the deployment of trust assessment across multiple domains, e.g. the physical and communications domains. The latter contribution includes the generation and optimisation of cross-domain metric composition or“synthetic domains” as a performance improvement method.

The Laird rams, built from 1862-1865, reflected concepts of naval power in transition from the broadside of multiple guns, to the rotating turret with only a few very heavy pieces of ordnance. These two ironclads were experiments built around the two new offensive concepts for armoured warships at that time: the ram and the turret. These sister armourclads were a collection of innovative designs and compromises packed into smaller spaces. A result of the design leap forward was they suffered from too much, too soon, in too limited a hull area. The turret ships were designed and built rapidly for a Confederate Navy desperate for effective warships. As a result of this urgency, the pair of twin turreted armoured rams began as experimental warships and continued in that mode for the next thirty five years. They were armoured ships built in secrecy, then floated on the Mersey under the gaze of international scrutiny and suddenly purchased by Britain to avoid a war with the United States. Once purchased, they were largely forgotten. Historians rarely mention these two sister ironclads and if mentioned at all, they are given short shrift. Built with funds obtained in part through the Confederate Erlanger loan, these ironclads were constructed at Lairds shipyard in Birkenhead and represented an advanced concept of ironclad construction through new proposals involving turrets, the ram, heavy guns and tripod masts on an armoured ship, as advocated by Captain Cowper Coles, R.N. They proved too much of a leap in one design but when their roles caught up to the revised designs, the ships were modified to meet new requirements. After several mission and design changes they then performed to standard. This belated success occurred when the concept of the ideal armoured warship was in flux throughout the middle Victorian years.