Stockpiling spare parts has always been the default safety net in the maritime and energy industry.
The approach carries costs that accumulate over time: warehouse space, handling, capital tied to slow-moving components, and parts that become obsolete before they are ever needed.
On-demand manufacturing is changing what having a part available really means. This article looks at why the traditional model is under pressure and what a leaner supply approach looks like in practice.
For OEMs managing large legacy portfolios, the financial case for physical stock becomes harder to justify over time.
Capital is tied up in parts that may never be used, especially in legacy parts. Warehousing, logistics, and handling costs compound with each passing year.
The assumption behind traditional stockpiling is that more stock equals more safety. In practice, this approach becomes less reliable as demand patterns shift.
Several pressures are converging to make the traditional stockpiling model worth re-examining. Global supply chain disruptions have exposed a structural weakness. Parts stocked in one location may be physically out of reach when demand arises. Geographic misalignment between inventory and end-user need creates delays that physical stock was supposed to prevent.
OEMs are under financial pressure to reduce excess inventory across their operations. Carrying large volumes of low-frequency legacy parts is increasingly difficult to defend at a portfolio level.
Vessel or asset owners are also reassessing their own approach. As awareness of more cost-effective sourcing models grows, they are less inclined to bulk-buy and store parts at their own expense.
On-demand is about producing what is needed, when and where it is needed, and in the quantity required. A key part of the model is producing components close to the point of need, reducing logistical delays rather than simply accelerating production at a central facility.
Parts are digitized, and production happens on-demand. There are a number of advantages to on-demand manufacturing:
The process begins with the OEM digitizing relevant parts from its legacy portfolio into a structured digital inventory. While production feasibility is an important factor, commercial considerations must be taken into account when deciding which parts to digitize.
When a part request is received, production is triggered through a certified manufacturing network. The component can be produced near the point of need or at a key supply hub, depending on location and logistical requirements. Lead times that once stretched to months can come down to weeks.
Full traceability is maintained from request to delivery and the relevant certification requirements are adhered to.
The global fleet is aging. According to data analyzed from Lloyd's List Intelligence, approximately 30% of global vessels are 20 years old or more, and many end users are currently focused on life-extension projects and maintaining legacy systems.
Legacy parts are the exact category where OEMs typically reduce stock first. As assets move into later lifecycle phases, production of older components is scaled back, and the supply gap between what operators need and what genuine makers can deliver quickly increases. When lead times for genuine parts stretch too long, operators turn to grey-market sources.
On-demand production gives OEMs a way to remain in that supply relationship without depending entirely on physical stock to do so.
One of the key challenges for most OEMs is that a substantial share of their portfolio experiences infrequent, unpredictable demand and relatively low order volumes.
Traditional inventory models treat availability as a physical stock problem. To ensure a part can be supplied quickly, the component must be manufactured, stored, managed, and carried in inventory long before demand appears.
This creates a difficult commercial equation for legacy parts. The cost of holding inventory continues whether a part is ordered or not.
Digital inventory changes that equation. Instead of investing capital in physical stock, OEMs establish a qualified digital production route that can be activated when demand arises. Availability is maintained through manufacturing readiness rather than warehouse volume.
For low-frequency components, this allows inventory decisions to be based on actual demand patterns rather than assumptions about future requirements. The result is a more flexible operating model. Physical stock can be reserved for high-volume or critical components, while suitable legacy parts remain available through an on-demand production pathway.
For OEMs managing large portfolios across maritime and energy sectors, this creates an opportunity to reduce inventory exposure without reducing aftermarket service capability.
Establishing the digital foundation ahead of demand, rather than in response to it, is what makes the model reliable.
For operators, the benefit is access to genuine parts without the need to purchase and store components years before they may be required. Procurement becomes more responsive to actual operational demand.
For OEMs, digital inventory introduces greater flexibility in how legacy portfolios are managed. Rather than making long-term stocking decisions across thousands of low-frequency components, inventory investment can be concentrated on the parts where physical stock delivers the greatest value.
The model also improves visibility into demand patterns. As more parts move through a digitized process, OEMs gain a clearer understanding of which components justify inventory, which are suitable for on-demand production, and where future supply decisions should be focused.
The outcome is a more efficient balance between availability, inventory cost, and aftermarket service performance.
Start by identifying the parts with the longest lead times or the highest risk of gray-market revenue loss. These are the components where on-demand manufacturing delivers the most immediate commercial and operational value.
OEMs need to gather the relevant drawings, quality standards, and certifications required for each part and work closely with their manufacturing partner. The manufacturing requirements, material specifications, and inspection criteria that define a genuine part need to be captured accurately before production can begin.
Before sharing any IP-sensitive information, OEMs should ensure protection through NDA agreements and align on compliance requirements with the manufacturing partner. Digitization of the parts portfolio is the first practical step.
Digital inventory is already being applied in maritime and energy to address real demand and supply problems. It does not replace stockpiling across an OEM's product portfolio. It complements it, providing a flexible and cost-effective route to supplying non-stocked legacy parts where traditional production at volume makes little commercial sense.
For OEMs still running a predominantly stock-based model for legacy parts, on-demand manufacturing offers a practical and commercially sound alternative worth evaluating now.
The question for OEMs is whether waiting longer to adopt it is worth the cost of the inventory model they are currently running.