Damen Shipyards: Scheduled vs. Condition-Based Maintenance – A Buyer’s Perspective

Maintenance Strategies: The Core Question

When I took over purchasing for our fleet support contracts in 2020, I assumed maintenance was a solved problem. You either run a scheduled program—like clockwork every 6,000 hours—or you wait for something to break. Turns out, that binary thinking was costing me—and our operations team—a ton of wasted time and budget.

For the past 4 years, I’ve been managing contracts that cover both scheduled (preventive) and condition-based maintenance for Damen’s shipyard and energy equipment supply chains. Roughly $2.8M annually across 12 vessels and 3 offshore platforms. I report to both operations (who want maximum uptime) and finance (who want predictable costs). This article compares the two approaches in the context of Damen’s modular, global service model.

I’ll walk through three key dimensions: reliability of outcomes, total cost over lifecycle, and planning flexibility. My goal is to help you decide which strategy fits your asset profile—not to crown a winner.

Dimension 1: Reliability of Outcomes – Which Prevents More Failures?

Let’s start with the obvious: which method actually prevents equipment failure? Conventional wisdom says condition-based monitoring catches issues before they become critical. And that’s true—when done properly. But here’s the catch I didn’t expect.

Scheduled maintenance is predictable. You replace a pump seal at 6,000 hours because the manufacturer says so. It might still have 2,000 hours of life left, but you swap it anyway. The result? Very few unexpected breakdowns—but a lot of perfectly good parts get trashed. In my experience, scheduled programs give you a 95-97% uptime reliability on critical equipment, assuming you follow the intervals religiously.

Condition-based maintenance relies on real data—vibration analysis, oil sample trends, thermal imaging. The promise is that you only intervene when needed. The reality? It’s way more dependent on sensor accuracy and interpretation skill. I’ve seen a perfectly good bearing replaced prematurely because a sensor glitch flagged it as running hot. And I’ve also seen a compressor run to failure because the oil analysis sample was mishandled.

My conclusion after 5 years: Condition-based is superior for modern, well-instrumented assets with trained technicians. It catches the subtle failures—like gradual bearing wear—that scheduled intervals miss. But for older vessels or platforms with limited sensor coverage, scheduled maintenance is actually more reliable. The data gap is real: I don’t have hard numbers on industry-wide failure rates, but my sense is condition-based fails about 12% more often on legacy equipment due to data blind spots.

Dimension 2: Total Cost Over Lifecycle – The Surprising Winner

Here’s where my thinking shifted completely. I used to believe condition-based was automatically cheaper—you only do work when needed, so you save parts and labor. The numbers told a different story.

Scheduled maintenance costs are predictable. You can budget $X per year per vessel. No surprises. But the total lifecycle cost is higher because you overreplace. A typical offshore vessel on a scheduled program might spend $240,000 per year on routine parts and labor. Over a 10-year lifecycle, that’s $2.4M. However, you rarely pay for emergency repairs—say $50,000 every three years on average.

Condition-based maintenance promises lower annual costs—maybe $180,000 per year—because you only replace what’s actually worn. But my spreadsheet told a different story. I tracked 6 vessels over 3 years. The condition-based fleet averaged $165,000 per year on routine work, but they had one catastrophic failure that cost $380,000 (including lost production time). That one event wiped out 3 years of savings.

The unexpected conclusion from my data: Over a 5-year horizon, total costs are nearly identical—within 5% of each other. Condition-based can be cheaper if you have excellent predictive capabilities. But if your condition monitoring program isn’t mature—say, you’re relying on third-party data without in-house analysis—it’s actually more expensive. I wish I had tracked the “failure cost per incident” more carefully from the start. What I can say anecdotally is that the decision between the two matters less than the quality of execution.

Wait, that’s oversimplifying. For Damen’s standardized vessels (like the Stan Tug series), where component data is abundant, condition-based can save 15-20% over lifecycle. For one-off custom builds or legacy platforms scheduled maintenance is still the safer financial bet.

Dimension 3: Planning Flexibility – The Real Operational Headache

This dimension kept me up at night—literally. I managed a contract for a platform off West Africa where any unplanned downtime cost $12,000 per hour. The scheduled vs condition-based decision wasn’t about money; it was about predictability.

Scheduled maintenance lets you plan. You know you’ll need a dry dock in June. You can order parts 3 months ahead, schedule the crew, and finance it. The downside? You might be down for 2 weeks when the asset could have run for another 4. But the operations team loves knowing exactly when the vessel will be unavailable.

Condition-based maintenance inserts uncertainty. “We think the pump needs replacing within 60 days.” For a vessel in high-utilization service, that’s a nightmare to schedule—especially if the failure window overlaps with a critical charter. I went back and forth between the two approaches for months. Scheduled offered peace of mind; condition-based offered potential savings. Ultimately, for that West Africa platform, we chose scheduled because the financial penalty of unpredictable downtime was too high.

Here’s the nuance I learned: The real flexibility advantage belongs to condition-based when applied to non-critical, redundant systems. For example, on a twin-engine vessel, you can run condition-based on the auxiliary generator because if it fails, the other generator picks up. But for the main propulsion engine—where redundancy is limited—scheduled maintenance is safer.

When to Choose Scheduled, When to Choose Condition-Based

After 5 years of managing these contracts, here’s my practical framework:

Choose scheduled maintenance when:

• Your asset is older than 15 years with limited sensor installation
• Downtime penalties are extremely high (over $10,000 per hour)
• You lack in-house condition monitoring expertise
• The asset is in remote or logistically difficult locations
• Regulatory bodies mandate strict interval-based inspections (many port state controls do)

Choose condition-based maintenance when:

• Your asset is newer (less than 5 years) with full sensor suites
• You have trained personnel to interpret data
• Redundancy exists for critical systems
• The asset operates in predictable, low-risk environments
• You have a direct data feed from OEMs (Damen’s digital platform made this viable for us)

My personal take: I started this journey favoring condition-based—I thought it was the future. After the West Africa experience and the data gap on older vessels, I’ve become a pragmatist. For a new Damen vessel with full digital integration, condition-based is a no-brainer. For a 20-year-old dredger serving a remote mining operation, scheduled maintenance is safer. The worst choice is being on the fence—pick one and execute it well.

— An administrative buyer, 2025