HomeShaft Power Limitation Systems (ShaPoLi) Made Simple: 2025 Update

Shaft Power Limitation Systems (ShaPoLi) Made Simple: 2025 Update

July 14, 2025

With the IMO’s EEXI rules now in full effect since 2023, many shipowners are turning to Shaft Power Limitation (ShaPoLi) as a practical, onboard solution to reduce fuel consumption and emissions. Instead of limiting engine output directly, ShaPoLi measures actual shaft power and restricts it by adjusting propeller pitch or shaft rpm. Unlike permanent modifications, it’s overridable in emergencies, logged for compliance, and helps vessels meet carbon standards while maintaining operational flexibility. Suppliers like Kongsberg, Chris-Marine, and Wärtsilä began deploying ShaPoLi-capable systems heavily in 2024–25, often bundled with torque meters and logging software.

🔧 What is it and Keep it Simple...

Imagine you’re driving a powerful truck, but new rules say you can’t go over 55 mph. Instead of changing the engine, you install a speed limiter that keeps you within the legal limit, but you can still push past it in an emergency if needed. That’s what ShaPoLi does for ships.

It limits how much power actually goes to the propeller by monitoring the shaft’s torque and rpm. If the ship tries to exceed its approved power limit, ShaPoLi holds it back, but always allows a manual override if safety is at stake. It helps shipowners comply with emissions rules like EEXI, without permanently downgrading the engine or going into drydock.

Shaft Power Limitation (ShaPoLi) – Pros and Cons
Category Pros Cons Notes / Caveats
EEXI Compliance Allows ships to meet power limits without modifying the engine Does not improve actual engine efficiency or emissions Accepted by class societies and IMO as an approved compliance method
Cost & Retrofit Lower cost than engine de-rating or installing energy-saving devices Still requires torque sensors, loggers, and override documentation Often installed without drydock; software-driven with minimal hardware
Operational Flexibility Override switch allows full power in emergencies or adverse weather Overrides must be logged and explained; excessive use may raise compliance flags Override logs must be reviewed during inspections and audits
Engine & Safety Impact Protects engine from unnecessary strain during routine ops Sudden override may cause load spikes without proper procedures Requires crew training and updated operational procedures
Integration & Monitoring Can be paired with CII dashboards and fuel efficiency systems Not useful if ship already operates well below design power Best for high-power legacy tonnage subject to stricter EEXI targets
Long-Term Relevance Gives shipowners more time before investing in alternative fuels or tech Seen by some as a temporary fix rather than a permanent solution May lose regulatory favor if stricter lifecycle carbon rules are adopted
Note: ShaPoLi is a practical compliance solution for EEXI limits, but must be paired with proper training, override logging, and a long-term decarbonization strategy.

2025 Snapshot: Is Shapoli Actually Working?

🔧 2025 ShaPoLi Rundown

  • ✔️ Already Installed: Hundreds of ships have implemented ShaPoLi to meet EEXI rules, especially bulk carriers and tankers built before 2013.
  • 💡 Simple Retrofit: Most setups include torque sensors, shaft RPM monitors, and a control limiter—hardware cost is modest.
  • 🛟 Emergency Override Built In: Captains can bypass limits when safety is at stake, but overrides must be logged and reviewed.
  • 📘 Class-Approved: Class societies like DNV, ABS, and Lloyd’s Register have issued guidance and approve ShaPoLi as an EEXI solution.
  • ⚓ Easy for Charterers: ShaPoLi doesn't require rerouting or voyage planning changes, making it attractive to operators under tight schedules.
  • 📉 Drawback: Since it limits power without improving actual efficiency, emissions aren't truly reduced—just capped by throttle.
  • 🚢 Works Best For: Ships that only occasionally run near full engine power; minimal operational impact when engines already run at 70–80% MCR.
  • 🔭 What's Ahead: Future EEXI or CII updates may make ShaPoLi insufficient alone—operators are watching closely.

📉 ShaPoLi ROI & Payback Calculator

Estimate how quickly your investment in a Shaft Power Limitation (ShaPoLi) system pays off based on compliance cost savings and operational benefits.



Typical range: $80,000–$150,000 depending on ship type and sensor setup.



Compared to alternatives like engine power de-rating or propulsion retrofits, ShaPoLi is often cheaper and quicker to certify.



Fuel savings (1–3%) may occur due to more consistent RPM control and lower peak loads.



Savings may come from reduced wear and smoother voyage planning within EEXI power limits.



Ongoing subscription or hardware calibration typically costs $5,000–$12,000 annually.

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