Excel vs Maritime CMMS: The Real Cost of Running Fleet Maintenance on Spreadsheets

There is probably not a shipowner in the world who did not start managing maintenance in a spreadsheet. One tab per vessel, a "next due" column, a red cell when the date gets close: Excel organised maintenance on thousands of ships long before dedicated software arrived, and it still does. That is neither naive nor shameful — it is usually the right first decision.

The problem is not Excel itself, but the moment the spreadsheet quietly stops doing its job: when the chief engineer and the superintendent are no longer looking at the same file, when nobody can show an auditor that a job was actually carried out, when a critical spare is missing because theoretical stock no longer matches the shelf. That tipping point never appears in a budget: it is paid for in administrative hours, emergency purchase orders and audit findings.

This article is not written to alarm anyone, but to set out the facts about running ship maintenance on a spreadsheet: why Excel wins the first round, the eight breaking points that appear as a fleet grows, what it really costs, how to migrate cleanly to a maritime CMMS, and when staying on Excel remains rational.

Why the spreadsheet wins at the start (and that is not a mistake)

Three reasons, all legitimate, explain why the spreadsheet always wins the opening round.

It is already there and costs nothing extra

The office licence is already paid for: no budget to defend in front of the owner, no tender process, no rollout. For an operator with one or two vessels discovering planned maintenance, opening a workbook is a five-minute decision, not a six-month project.

Everyone already knows how to use it

A chief engineer, a master, an accountant, an agent: all can sort a column and write a simple formula. No training, no change management, no resistance — and on board, where crew rotation is high, that familiarity carries real weight.

It bends to exactly how you work

A spreadsheet imposes no data model. You invent your own coding, add a "chief's remarks" column on Tuesday and delete it on Thursday, paste a photograph into a cell. That plasticity is what rigid software cannot offer — and the root of every problem that follows.

Excel is not a bad maintenance tool. It is an excellent tool for recording maintenance. The tipping point comes the day you expect it to become a tool for controlling maintenance and proving it.

The 8 breaking points as the fleet grows

These failures do not all arrive at once: they typically surface between the third and fifth vessel, or at the first serious audit.

1. Ship and shore versions diverge

The file is emailed to the vessel, comes back edited, and crosses paths with another version edited ashore: soon you have "PMS_fleet_v7_final_OK_updated_CE.xlsx" and nobody knows which row is authoritative. The superintendent works on data three weeks old, while the vessel follows a plan already changed ashore — the leading cause of jobs done twice, or not at all.

2. There is no reliable history per item of equipment

In a spreadsheet, the last-done date is overwritten by the next one: history disappears, or survives scattered across archived tabs nobody reads. So you cannot answer the question that matters: "how many running hours has this turbocharger done since its last overhaul, and what was found?". A structured equipment register keeps every job attached to the asset, with counter reading, parts fitted and findings.

3. Certificate and survey deadlines slip through

Statutory certificates, class surveys, renewal windows, extensions: a spreadsheet warns nobody, it waits to be opened. A missed expiry can mean detention by port State control, off-hire and sometimes an insurance discussion — the most asymmetric risk on this list, low probability and heavy consequence. A certificates module with automatic alerts removes this failure mode.

4. No running-hours triggering

Machinery maintenance is rarely calendar-based; it is hours-based (250 h, 500 h, 1,000 h, 5,000 h). A spreadsheet knows nothing of the actual running hours of your main engines, generators, compressors and separators. Readings are retyped by hand, then due dates recalculated by hand, weekly, per vessel: tedious, therefore late, therefore wrong. Counter-driven maintenance linked to the PMS is exactly what a spreadsheet will never do.

5. Stock figures stop being trustworthy

Theoretical stock diverges from physical stock the first time a part is taken in a hurry without being booked out. Two months later nobody trusts the file: people order "just in case", double the levels, tie up working capital — and still run out of the one critical part. See our article on MRO stock management and avoiding critical spare stockouts.

6. No defensible audit trail for ISM, class or Flag State

The most serious breaking point. An Excel file is editable, back-datable and not time-stamped: it is not evidence. In an internal ISM audit, a Flag State inspection or a class survey, the auditor looks for consistency between plan, execution, non-conformities and corrective actions. A spreadsheet shows neither who did what nor when. We explore that in ISM Code and CMMS: maintenance compliance.

7. Everything depends on one key person

There is always someone who "knows the file": their formulas, their colour codes, their hidden tabs. The day that person takes extended leave, moves company or retires, the knowledge leaves with them — an operational risk rarely identified as such.

8. No mobility, and above all no usable offline mode

The spreadsheet lives on a PC in the engine control room, yet maintenance is observed in the engine room, in the tank, on deck, usually with no connectivity. So people write on a notepad or a phone — then retype it, and that double entry is where accuracy and much of the time are lost. A mobile app that genuinely works offline and syncs on reconnection removes the step.

Excel vs maritime CMMS: a line-by-line comparison

Twelve criteria determine the quality of a shipboard maintenance system. Here is how the two approaches compare.

The real cost of the spreadsheet: an order-of-magnitude calculation

The most useful exercise — and the most debatable. We own that: the figures below are orders of magnitude observed in the field, not a statistical study, and they are only worth something if you replace our assumptions with your own.

The assumptions, stated openly

• Reference fleet: 5 vessels in sustained operation.
• Fully loaded hourly cost: EUR 45 for a chief engineer, EUR 55 for a superintendent — figures that vary widely by flag and segment.
• We count only the administrative overhead caused by the spreadsheet, not the maintenance work itself.
• Basis: one full year, 46 active weeks.

The chief engineer's administrative time

Updating the file, retyping counter readings, recalculating due dates, rebuilding the monthly report, hunting for missing history: 2 to 4 hours per week per vessel is conservative on reasonably complex units. Take 3 hours: 3 h × EUR 45 × 46 weeks × 5 vessels ≈ EUR 31,000 per year.

The superintendent's time ashore

Consolidating files, reconciling versions, chasing missing data, preparing audit and drydocking packs: 4 to 6 hours per week for five vessels is common. Take 5 hours: 5 h × EUR 55 × 46 weeks ≈ EUR 12,600 per year.

Emergency purchasing

When stock data is unreliable, a share of orders becomes urgent: express freight, unapproved supplier, unnegotiated price, delivery alongside in a distant port. The premium over a planned order frequently runs between +30% and +100%: ten avoidable emergency orders a year at EUR 1,500 average premium comes to EUR 15,000 across five vessels. A purchasing process linked to stock and maintenance mechanically reduces this line.

Off-hire and non-conformities

The most variable line and the most dangerous to quantify: a day of unplanned downtime costs a few thousand euros on a harbour craft and tens of thousands on a ferry or offshore unit. We deliberately count only one avoidable day per year for the whole fleet, valued at EUR 8,000 — a low assumption, chosen so as not to inflate the total. Add audit findings: every major non-conformity triggers a corrective action plan and a re-verification, say EUR 3,000 a year in internal time.

The total, and how to read it

That is roughly EUR 14,000 per vessel per year. For comparison, a full maritime CMMS subscription sits at around EUR 100 to 150 per vessel per month, or EUR 1,200 to 1,800 per vessel per year (see our pricing).

Be honest about the limits here. A CMMS does not remove 100% of that cost: it typically removes half to two thirds of the administrative lines and adds its own data-entry time. Simple fleets will not lose 3 hours per week per vessel; a ferry or offshore fleet will exceed these figures. The message is not "spreadsheets cost EUR 69,600" — it is that the cost is invisible and considerably higher than the software as soon as you pass a handful of vessels.

How to migrate cleanly from Excel to a CMMS

Most CMMS projects that fail do not fail on the software; they fail on data migration. Here is the sequence that works.

Step 1 — Clean before importing, never after

Importing a dirty spreadsheet produces a dirty CMMS, only faster and more visible. Before any import: remove duplicates, strike out landed items, harmonise naming ("ME port", "M/E PS", "Main engine port" are one machine), check counter units and settle contradictory intervals. A few days of thankless work that determines everything else.

Step 2 — Decide the coding structure before loading

Adopt a stable hierarchy: vessel → system → sub-system → equipment → component, based on SFI-style coding or a consistent in-house standard. The reference matters less than the fact that it is identical across every vessel in the fleet — otherwise consolidation stays impossible. Our four-step guide to building a planned maintenance programme covers this structuring in detail.

Step 3 — Import in batches, starting with a pilot vessel

Never import the whole fleet at once. Take one representative vessel and load equipment, then job specifications, spares and certificates — each layer builds on the previous one. Have the chief engineer validate it: he will spot at once that an interval is wrong or a machine missing.

Step 4 — A controlled, time-boxed parallel run

For 4 to 8 weeks, run the spreadsheet and the CMMS in parallel on the pilot vessel — not to duplicate work, but to check that nothing falls between the two systems. Set a spreadsheet switch-off date at the outset and hold to it: a parallel run with no end date becomes permanent, and the CMMS never becomes the reference. Our article on the five mistakes to avoid when implementing a CMMS returns to this trap in detail.

Step 5 — Roll out the fleet and keep training short

Once the pilot vessel is stable, the remaining ships take far less time: coding structure and standard job specifications already exist. Plan short, practical onboard training focused on three actions — take a counter reading, close out a job, issue a spare.

When Excel is still perfectly adequate

Plainly: in some situations, moving to a CMMS adds little. A spreadsheet is enough if you tick most of these boxes:

• 1 to 2 technically simple vessels, with no complex machinery or critical automation.
• A stable crew where the same person has followed the vessel for years.
• A limited number of certificates and a documentary system already under control.
• Little or no onboard stock: parts bought as needed from a responsive local supplier.
• No consolidated reporting owed to an owner, a charterer or an insurer.

Energy is then better spent making the spreadsheet rigorous: one row per item of equipment, a last-done date never overwritten, a certificate expiry tab, a backup held off the machine. The question returns when you add a third vessel, or a charterer asks for a maintenance report.

Key takeaways — Excel is excellent for recording maintenance, unsuited to controlling it and incapable of proving it. The eight breaking points usually appear between the third and fifth vessel, or at the first serious audit. The cost appears in no budget: it hides in administrative hours, emergency purchasing and downtime, and on a five-vessel fleet it comfortably exceeds a subscription. And 80% of a successful migration is decided by data cleaning and coding, not by the software.

FAQ

Does Excel comply with the ISM Code for planned maintenance?

The ISM Code mandates no particular tool: it requires the Company to establish a planned maintenance system, carry out inspections at appropriate intervals and retain records. A spreadsheet can in theory satisfy that, but it creates an evidential problem — a file editable with no time stamp and no named author is hard to defend in an audit. Flag State and class auditors accept Excel on simple vessels and question it as the fleet grows.

At how many vessels should you leave the spreadsheet behind?

There is no universal threshold, but the tipping point most often observed is around three vessels, or at the first vessel with complex machinery and a dense running-hours plan. The indicator is not the number of hulls: it is the time your superintendent spends reconciling files instead of analysing data.

Can an existing Excel file be imported into a CMMS?

Yes — equipment, job specifications, spares and certificates all import from Excel or CSV. But an import corrects nothing: inconsistent naming and duplicates produce an inconsistent database. Cleaning and coding upstream is where the effort lies — allow a few days per vessel.

What happens when the vessel has no internet connection?

This criterion disqualifies most general-purpose maintenance software. A maritime CMMS must let the crew view the plan, close out a job, enter a counter reading and issue a spare entirely offline, then synchronise on reconnection. Test it during a trial rather than taking it on trust.

Conclusion: it is not Excel versus CMMS, it is knowing when to switch

Excel has nothing to apologise for: it has let thousands of operators structure their maintenance with no budget and no IT project, and will keep doing so for small vessels. But a spreadsheet is a recording tool, not a control system — it cannot trigger, alert, prove or synchronise between ship and shore.

So the right question is not "is Excel bad?" but "when does its invisible cost exceed the visible cost of software?". Run the numbers with your own rates, vessel count and history of emergency orders. If the result surprises you, the switch should probably have happened a year ago.

Smart Sailors builds a maritime CMMS designed by seafarers, deployed on more than 400 vessels, with an offline mobile app and twelve modules covering maintenance, equipment, spares, purchasing and certificates. Book a demonstration or start your free 30-day trial: the best way to find out what your spreadsheet costs you is to try doing without it for a month.