Ukraine says it has destroyed around a third of Russia’s Black Sea Fleet using asymmetric methods, including, most notably, uncrewed surface vessels (USVs). And this has rightfully stimulated the production of these small, plucky platforms around the world.
However, it is not enough to reproduce these proven hulls for a variety of missions. While it is fairly straightforward to produce lots of ten-metre long USVs for a one-way effect in littoral waters, it is another more complicated endeavour to produce a scalable, survivable, and modular USV as part of a hybrid fleet – a key priority of the UK Royal Navy, mapped out by the authors of the Strategic Defence Review.
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To this end, BMT will debut its new family of Modular Uncrewed Ships, or MODUS, at the Defence Security International Exhibition (DSEI) at the Excel in London between 9-12 September 2025. The company has put forward pre-concept designs for a medium USV (40 metres) and a large USV (75 metres) based on more than six years of research into the fledgling market.
In an exclusive interview with Naval Technology before the event, Jake Rigby, head of innovation and research, identified the nuances behind introducing autonomous warships into the hybrid surface fleet.
Take a step back
A common approach to USV construction is simply re-fitting existing crewed surface vessels to make them autonomous. For example, L3Harris offers its ASView control system to enable this conversion.
While understandable, Rigby dismissed this optionally-crewed concept to autonomous shipbuilding as it does not provide the transformative effect of autonomy.
“What we’re proposing is a bit more of a stepping stone approach,” Rigby discerned. Although MODUS vessels may not look much different from other USVs, it is what is on the inside that matters, and here, Rigby claims, is what is different:
“We threw out the rule book on how to design ships,” he argued, “simple things like bulkheads, segmentation, and deck heights – forget all of that. You’re designing a completely autonomous ship, so you have to really think from the ground up what is required.”
The MODUS vision
As a crewless platform, USVs only need the bare essentials at sea. With no need to accommodate humans, Rigby suggested that autonomy has likely freed up ~30% internal space for core requirements. But at the same time this then shifts the challenge from the volume-driven to a weight-driven design.
Still, this gives rise to a tendency for navies to prioritise the end capability. For the Royal Navy, anti-submarine warfare (ASW) in the North Atlantic is the foremost priority, tackling Russian submarine activity more than anything else.
To help with this, MODUS will focus on ASW, seabed warfare, and data-gathering. Although, Rigby also revealed that a fourth element – anti-air warfare – is currently in development.
“The key differentiators and measures that we want to get across [at DSEI] is that we have not chosen a single hull design that can be applied to multiple different scenarios,” Rigby emphasised.
“From our research, it’s more cost effective to design a hull that’s right for that purpose and then it gives you that competitive edge in that purpose but it has modularity and [common] design principles across [the family of systems].”
Cost and construction
BMT upheld the affordability of the MODUS family but when asked about the cost per unit, no discernible figure was presented. However, Rigby explored several factors that come together to determine this variable price.
Cost depends on the supply of the shipbuilder that will partner with BMT, a maritime construction consultancy, to bring the MODUS concept to a reality. In their current state, these USV designs constitute an informed approach to future USV production.
Materials also influence the cost. Although steel is recommended, BMT explored the possibility of using aluminium and composite elements.
“If you built it out of aluminium, you would have a better range, be more lightweight, have more fuel on board. It is a weight driven design, so there are clear benefits but it undermines the cost. I cannot stress further that value engineering has been at the core of this kind of design mentality,” Rigby added.
Meanwhile, the construction and lifecycle of MODUS will revolve around existing crewed vessels’ build schedules “and the UK has a limited build capability which is already maxed out for quite a few years to come,” Rigby observed, and this schedule cannot be undermined by USV construction.
BMT’s solution is to lean on commercial shipyards: “I think in the UK especially, we are very lucky to have a really strong industry of wider small boat and wider manufacturers that are used in yacht and pleasure craft as well. One proposal we’re looking at is to fit this into the wider schedule, have some of those [commercial] yards take this piece on and and build that capacity.”
DSEI 2025 will take place at the London Excel between 9-12 September. You can find out more information about the exhibition here.
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