Main Engine Performance

End-to-end pipeline that captures main engine telemetry, classifies cylinder uniformity, scores SFOC variance and overhaul exposure, and produces a TSI-grade expert review.

Main Engine Performance — six-month parameter rollups, cylinder uniformity, SFOC variance, turbocharger health, and overhaul timing in one TSI-grade review.

Executive summary

The main engine is the single most expensive equipment item on a vessel and the single largest fuel consumer. A 5% SFOC drift means several hundred dollars per day at sea — at scale, hundreds of thousands per year per vessel. A late cylinder overhaul means an engine failure at sea — usually the most expensive recovery a fleet ever sees. A misbalanced cylinder means an asymmetrically worn liner — eventually a major overhaul that should have been a top-end.

The Main Engine Performance pipeline turns the existing data — ERP monthly performance reports, telemetry exports, the engine register — into something a Technical Superintendent can act on without reading every monthly file. It captures a six-month rolling window of every monitored parameter, computes deviations against the maker’s design and against the rest of the fleet, and routes anything that crosses an operating threshold to the right person.

Architecture

       ┌──────────────────────────────────────────┐
       │  ERP telemetry  ·  Engine register  ·  Forms │
       └──────────────────────┬───────────────────┘
                              │ monthly reports + specs
                              ▼
       ┌──────────────────────────────────────────┐
       │   Stage 1 — Collection                    │
       │   Standard collector  +  Microapp        │
       │   collector (with screenshots)           │
       └──────────────────────┬───────────────────┘
                              │ structured telemetry
                              ▼
       ┌──────────────────────────────────────────┐
       │   Stage 2 — Analysis                      │
       │   • Cylinder uniformity                   │
       │   • SFOC variance vs design               │
       │   • Pressure deviation                    │
       │   • Turbocharger health                   │
       │   • Overhaul timing                       │
       │   • Six-month parameter rollup            │
       └──────────────────────┬───────────────────┘
                              │ verdict + scores
                              ▼
       ┌──────────────────────────────────────────┐
       │   Stage 3 — Expert review                 │
       │   Auto-escalate to TSI when triggered    │
       └──────────────────────────────────────────┘

---

Stage 1 — Data collection

Where the data comes from

Source	What it provides
Vessel ERP	Engine register, monthly performance reports, running hours, alarms history
ME Performance microapp	Polynomial baseline curves, shop-trial overlays, deviation analysis
Vessel-side ME performance form	Monthly per-cylinder data filed by Chief Engineer
PMS counter feed	Hours since cylinder / top-end / major overhaul

ERP records the structured engine register and monthly reports; performance forms are vessel-side submissions; the microapp adds the visual evidence layer for owner / charterer correspondence. The pipeline supports two collectors with the same downstream contract:

Standard collector

Pulls the latest performance entry from the ERP telemetry feed for one vessel at a time. Output is a single structured record covering the most recent reporting period.

Microapp collector (with visuals)

Drives the ME Performance microapp via a headless browser, captures the API responses for performance, baseline polynomials, and shop-trial data, and bundles a screenshot of every dashboard tab. Used when the senior review will reference the live microapp visuals — typical for charterer or owner submissions.

What gets captured

Domain	Data
Engine state	Running hours, RPM, load, power output
Per-cylinder	Pmax, Pcomp, exhaust temperature, FW inlet/outlet temp, PCO outlet
Combustion	Mean indicated pressure, peak pressure, scavenge pressure
Aspiration	Turbocharger speed, boost pressure, exhaust back-pressure
Maintenance	Hours since last cylinder, top-end, and major overhaul
Alarms	Active alarms with severity at sample time

Microapp collection adds:

• Polynomial baseline curves used by the microapp for deviation overlays
• Original shop-trial values for comparison
• Tab-by-tab screenshots: overview, deviation, trends, cylinder, turbocharger, alarms

Output

Both collectors append a timestamped record to the vessel’s main-engine case folder with the exact same fields, so the analyzer is collector-agnostic.

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Stage 2 — Analysis

2.1 Cylinder uniformity

Even cylinder loading is the single most important indicator of engine health. A cylinder running hotter than its neighbours points to a fuel-injector defect, a stuck exhaust valve, or piston-ring blow-by — usually weeks before the engine itself flags an alarm.

The analyzer computes deviation per cylinder:

$$\Delta T_i = T_i - \bar{T}, \quad \bar{T} = \frac{1}{N}\sum_{i=1}^{N} T_i$$

Verdict:

Severity	Threshold
OK	$\lvert \Delta T_i \rvert \leq 30\,°\text{C}$
WARNING	$30\,°\text{C} < \lvert \Delta T_i \rvert \leq 50\,°\text{C}$
CRITICAL	$\lvert \Delta T_i \rvert > 50\,°\text{C}$

The same deviation maths runs on Pmax and Pcomp. A cylinder that is hot and has low Pmax is the classic exhaust-valve signature; a cylinder that is hot and has high Pmax usually points to fuel-injector overdelivery.

2.2 SFOC variance

Specific Fuel Oil Consumption is load-dependent — comparing raw values across operating points produces nonsense. The analyzer always normalises to the maker’s design SFOC at the current load:

$$\text{Variance \%} = \frac{\text{SFOC}_\text{actual} - \text{SFOC}_\text{design}(P)}{\text{SFOC}_\text{design}(P)} \times 100$$

A 3-point moving average smooths month-to-month noise; persistent variance above 5% is flagged, above 8% triggers escalation.

2.3 Six-month parameter rollup

Trend matters more than spot values. The analyzer builds a rolling six-month grid of every monitored parameter — per cylinder per month — and surfaces parameters whose mean is drifting. Missing months are surfaced too: a vessel that hasn’t filed a performance report for three consecutive months is itself a red flag.

Code snapshot

The dashboard logic that drives the rollup, condensed:

# Build a six-month grid keyed by (cylinder, month), values from performance reports
for unit in sorted(all_units):
    unit_row = {"units": unit}

    for month_date, month_label in zip(six_months_dates, six_months_labels):
        performance = performance_data.get(month_date)

        if performance == "No Data Available":
            current = (month_date.month == datetime.utcnow().month and
                       month_date.year  == datetime.utcnow().year)
            unit_row[month_label] = "Report yet to be submitted" if current \
                                    else "Missing Report"
            continue

        unit_data = next(
            (u for u in performance["data"]["parameter"]
             if u.get("ENGPERTRANSLINENO") == unit),
            None
        )
        unit_row[month_label] = (
            round(unit_data[parameter_key], 2)
            if unit_data and unit_data.get(parameter_key) is not None
            else "No Data Available"
        )

Two pieces of nuance matter: the analyzer distinguishes “report yet to be submitted” (current month — expected gap) from “missing report” (past month — actual gap). The first is a forms problem; the second is a compliance problem.

2.4 Pressure deviation

Peak combustion pressure, mean indicated pressure, and scavenge pressure are checked against the maker’s spec for the operating point. The analyzer maps deviations to specific failure modes:

Pattern	Likely cause
Pmax low + Pcomp normal	Fuel injector overdelivery / late timing
Pmax high + Pcomp high	Excessive compression — piston ring overhaul candidate
Pmax normal + Pcomp low	Compression loss — exhaust valve or ring pack
Scavenge low + exhaust back-pressure high	Turbocharger fouling
Scavenge low + cooler ΔT low	Scavenge cooler fouling

2.5 Turbocharger health

Turbocharger boost low and exhaust back-pressure high is the textbook turbo-fouling signature. The analyzer computes:

$$\eta_\text{tc} = \frac{P_\text{boost}}{P_\text{exhaust\_back}}$$

A falling $\eta_\text{tc}$ across three reports is flagged for cleaning regardless of whether either pressure is individually outside spec.

2.6 Overhaul timing

Hours-to-next overhaul are computed against the maker’s interval:

$$H_\text{remaining} = H_\text{interval} - (H_\text{current} - H_\text{last\_overhaul})$$

Tier mapping:

$H_\text{remaining}$	Status
$< 0$	Overdue — CRITICAL
$0 \leq H_\text{remaining} < 500$	Imminent — escalate
$500 \leq H_\text{remaining} < 2000$	Port-call coordination
$\geq 2000$	Healthy

---

Worked example

Vessel: MV ONE ATLAS (IMO 9290127), MAN 8K90 MC-C.

After a refresh, the analyzer reports:

Domain	Finding
Cylinder uniformity	Cylinder 5 exhaust temp 38 °C above mean — WARNING
SFOC	6.8% variance over design at 75% MCR, sustained 3 months — flagged
Pressure	Cylinder 5 Pmax 12 bar below mean, Pcomp normal — points to fuel-injector overdelivery
Turbocharger	$\eta_\text{tc}$ down 9% over 3 reports — cleaning recommended
Overhaul	Cylinder 5 top-end overhaul in 380 hours — escalate

Composite verdict: HIGH — cylinder 5 has converging signals (hot, low Pmax, near overhaul). The pipeline:

1. Sets escalation flag, priority CRITICAL
2. Updates the case to awaiting-tsi-review
3. Sends an A2A message to the TSI inbox with the per-cylinder evidence and the recommended actions

Recommended actions (from the analyzer):

1. Schedule cylinder 5 fuel-injector replacement at next port — coordinate spares.
2. Schedule turbocharger water wash within 7 days; wet-cleaning at next port.
3. Plan cylinder 5 top-end overhaul at the next docking window — book superintendent attendance.

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Output deliverables

• Executive summary — overall ME status, headline findings
• Cylinder uniformity table — per-cylinder deviation, severity, likely cause
• SFOC analysis — variance trend, cost impact, root-cause candidates
• Six-month parameter rollup — every parameter per cylinder per month, gaps surfaced
• Pressure analysis — deviation per cylinder, mapped to failure mode
• Turbocharger assessment — $\eta_\text{tc}$ trend
• Overhaul plan — urgent / upcoming, port-call coordination
• Recommendations — prioritised actions with timeline and cost
• Escalation decision — auto-routed to TSI when triggered

When microapp collection is used, the deliverable also embeds the captured screenshots so the review references the same visual the operator sees in production.

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Escalation triggers

Trigger	Severity
Cylinder deviation above 50 °C	CRITICAL
SFOC variance above 8% sustained	HIGH
Cylinder overhaul overdue	CRITICAL
Turbocharger boost low + exhaust high	HIGH
Peak pressure outside maker spec	HIGH
Three or more missing monthly reports	HIGH

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Why script-driven

Cylinder-deviation maths, SFOC-curve normalisation, and pressure-spec lookups all live in deterministic Python templates. The model interprets results into narrative; it doesn’t recompute. That means a review of POSUN this month and the same review next month produce identical numbers given identical inputs — which is the only way an audit trail holds up.

The microapp collector and the standard collector produce the same downstream record. The choice is operational: when a review will be referenced by a charterer or in a Class dispute, use the microapp collector so the screenshots travel with the numbers.

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References

Source templates

Performance analysis suite — ME monthly parameter rollup and engine specifications & running hours.

Related: Auxiliary engines

Same analysis pattern, applied to AE generators.

Related: Lube oil

Wear-metal trends often confirm or rule out a cylinder finding.

Related: Fuel oil

Fuel quality is the most common root cause for sustained SFOC variance.