Powering into the Future - Propulsion Options for Surface Combatants

There have been many papers presented over the years claiming to put a definitive, ideal propulsion system forward for a particular vessel, with solutions varying from Mechanical through Hybrid, to Integrated Full Electric Propulsion. The ships associated with these differing propulsion systems also vary hugely, from small offshore patrol boats through larger platforms, such as Type 23, Type 45 and potentially her successor in the destroyer category, to the largest ships ever commissioned to the Royal Navy, the Queen Elizabeth class aircraft carriers. This paper seeks to explore the range of options available, with some of the pros and cons of different solutions, through a lens of differing ship types, and mission/role profiles. The aim is not to conclude a definitive solution, but provide the discriminators/differentiators to be considered when making the selection. Aspects to be considered as part of this analysis comprise a range of differing drivers and constraints including: ship’s lifespan, vessel size, operating environment, combat role, likely operating profile, future-proofing requirement, such as the growth and impact of non-propulsion loads, potential crew/maintenance impacts, the desire for fleet commonality and emerging requirements, such as emissions and neutral/zero carbon aspirations as well as affordability and cost of ownership. While none of these aspects alone will provide a definitive discriminator to the selected option, each of them influences the choice in a unique way. Selecting the 'ideal'  propulsion becomes an exercise in trading off each of the competing demands in order to find a suitable solution.The replacement for Type 45 will be considered in more detail by the authors, whose companiesbetween them have been the leading suppliers of propulsion systems and shipbuilding for the post-Cold War UK Navy.