Technical note | An Investigation into RAN Ship Structural Life-of-Type Management without Hull Monitoring Systems

ABSTRACT

A preliminary study was conducted on the considerations, assumptions, and options for managing the structural Life of Type (LOT) of new Royal Australian Navy (RAN) ships without ship Hull Monitoring Systems (HMS). The study used critical thinking, or 'red teaming' techniques, to identify the consequences of not implementing HMS on board RAN ships, as well as to identify LOT management strategies that do not use HMS. The key consequence is that the RAN's ability to manage LOT risks and fleet availability will be impacted. Three alternative LOT management strategies were identified and would lead to a lower level of confidence in the management of RAN ship LOT risks. This is mainly due to the need for accurate data on the ship's operational usage to manage its LOT risks with a high degree of confidence. This data, in combination with emerging technologies such as the Digital Twin, provides opportunities for condition-based maintenance and support for the RAN to be a 'smart owner'. Implementing HMS on board RAN ships will however incur through-life financial and human resource costs and decision-makers will need to trade off these costs with the LOT management and other benefits.

Executive Summary

In this report we describe a preliminary study on the considerations, assumptions, and options for managing the structural Life-of-Type (LOT) of new Royal Australian Navy (RAN) ships. The purpose of the study was to identify and investigate the risks and consequences of not implementing a hull monitoring system (HMS) on-board naval ships, to support the RAN to:

• manage the LOT of the fleet
• deliver seaworthy materiel throughout the capability lifecycle
• support the RAN to be a ‘smart owner’ through the adoption of a Digital Twin approach.

In the study, structured needs assessment and red teaming were employed with a group of Defence Science and Technology (DST) Group researchers. The first stage in the study was a SWOT analysis of implementing HMS on board naval ships. The SWOT analysis identified the key strength of implementing HMS is that it supports the RAN to manage a vessel’s LOT risks. The study then explored this strength further by utilising red teaming techniques to minimise the influence of cognitive biases on the investigation. These techniques, which included a data review, structured brainstorming, and key assumptions checking, enabled the identification of approaches to manage the LOT of RAN ships without using a HMS. Three categories of approaches were identified:

1. employ an inspection regime (time- or predictive-based)
2. utilise other data sources (for example, logbooks, hindcast weather data, fatigue damage estimated via simplified or computational approaches)
3. manage LOT uncertainty by implementing alternate vessel management strategies, (e.g. restrict a ship’s operations or service life).

The assumptions that underpinned these approaches were then identified and questioned using a key assumptions check. Through this questioning, it was discovered that the three categories of approaches for LOT management without a HMS would lead to sub-optimal through-life management of RAN ship LOT risks. This is mainly due to the need for accurate data on the ships operational usage in order to manage the LOT risks with a high degree of confidence. Ideally, a HMS would be coupled with all three approaches to provide a comprehensive strategy. Implementing HMS on board RAN ships will however incur through-life financial and human resource costs and decision-makers will need to trade off these costs with the LOT management and other benefits. Other opportunities  provided by HMS could include the ability to use the operational data for fleet maintenance and operations planning. This would enable the RAN to optimise fleet usage, maximise fleet availability for operations and support the RAN to be a ‘smart owner’.

A final conclusion from the study is that the red teaming approach used to identify underlying weaknesses of the alternative approaches of naval ship LOT management was effective. Further work could utilise the study approach with participants from various Defence stakeholder groups to ensure a broad range of perspectives on the topic are captured.