Submarines are high value assets that require material integrity and equipment reliability, to operate in an extremely hostile environment. Physical and financial constraints, as with any design and build, require an assessment of the acceptable level of risk that allows a submarine to operate safely and be affordable. These risks need to be robustly managed from identifying and quantifying the associated risk in the design stage, to assessing the risk associated with build quality and in-service degradation. Surface ships and submersibles, both commercial and naval, have a well-defined and prescribed product verification process in the form of Class Society Rules, adoption of which will provide assurance of the design safety, build quality and in-service capability in an industry accepted approach. However, these cannot be directly applied to a submarine. The assurance process applied to a submarine must recognise and address: its unique operating environment, risks that are unique to a submarine operation and the physical constraints imposed on the submarine. The number of submarine operating navies, capable submarine designers and builders in the world are limited. There are restrictions on the sharing of technology, design and build methods. This presents a challenge to the development of a common traditional prescriptive rule based assurance process that would be internationally acceptable and available to all. Safe in service operation requires recourse to the original design intent, standards, and assumptions. Complex contracting arrangements may make it difficult to access such information particular as time passes. A common framework which provides a consistent rigorous method of assessment, record of design intent and record of construction from an independent third party will greatly assist safe in-service operation. A goal based assurance approach benchmarked against industry practice can provide a solution to these problems. This paper demonstrates how an assurance processes can be successfully applied in full or in part to a submarine, system or equipment for the build and in-service programme using LR?s new Submarine Assurance framework.