Marine Shaft Power Meter Systems


Marine Shaft Power Meter Systems – The Energy Efficiency Design Index (EEDI) and the Ship Energy Efficiency Management Plan (SEEMP) requirements were made legally binding by the MARPOL Annex VI, the first climate change treaty to be adopted since the Kyoto Protocol. The technical requirements in this treaty are aimed at promoting the use of more energy efficient (less polluting) equipment and engines. In determining the best way to save fuel, we must initially understand how it is utilised and how efficient the vessel is, in converting the energy. A complex ship system will already provide much of the information required to ascertain fuel usage and maintenance of the vessel but a measurement of shaft power can show the efficiencies.

As a result, we developed Marine Shaft Power Meter Systems to meet the requirements of the Commercial Marine customers to provide ongoing power monitoring data on ships. The current usage of the systems is to provide data for fuel economy and equipment maintenance planning programs. Fitted at an early stage the torsion meter system can be used in Ship Acceptance Trials and from that point on be a measure of the condition of the ship throughout its life cycle

Shaft Power Meter Features

  • Fully Modular System: Shafts from 150mm to 1,100mm (and above)
  • 100% Contactless
  • Maintenance Free
  • Highly Reliable
  • Instrumentation Accuracy: 0.1%
  • System Accuracy: 0.1%
  • System Repeatability: 0.05%
  • Multiple Outputs: RS485, RS232, Modbus, Ethernet, 0-10V, 4-20mA, and USB Logging
  • Operating Temperature: -15˚C + 80 ˚C
  • Environmental Sealing: IP67
  • Supply Voltage: 110 – 230 Vac, III or I, AC or DC 12-24V
  • Can Be Installed and Commissioned in 1-2 days
  • One-Time Calibration (No Re-Zero or Re-Calibration Required)

Shaft Power Measurement

Shaft Power is an essential Input to Ship Performance Monitoring Systems. The data from monitoring actual power levels provide an accurate reference point to assist with assessing:
  • Engine Performance Monitoring
  • Ship Propulsion Efficiency
  • Hull Condition
  • Propeller Condition
  • Specific Fuel Consumption
  • Operational Efficiency Planning
  • Ship Condition Changes


The Thrust Power ratio data is extremely valuable and can be obtained from our Marine Shaft Power Meter. To improve energy efficiency of a ship, two main factors need to be met:
  1. Fuel Used /Engine Power to be a maximum
  2. Thrust /Engine Power to be a maximum
The purpose of a propeller is to convert the power and torque provided by the engine, into thrust.  The design of a propeller should deliver the most efficient forward (ahead) movement of the vessel. It will also provide backward (astern) movement of the vessel, depending on propeller type this can be compromised in favour of forward or ahead efficiency. By implementing our Marine Shaft Power Meter, you can use the torque and thrust readings to monitor the condition of the ship’s hull and propeller. Over a period of time, should the torque value increase while maintaining the same speed, it is clear that something is under-performing – this could be anything from a shaft bearing to wear on the propeller or even hull fouling. Typically, with a propeller in the ideal condition you will get the maximum thrust for the power you input. If a propeller is damaged or fouled, the thrust/power ratio will be lower. The Datum Shaft Power Meter measures and records: Torque (Nm), Speed (RPM), Thrust and Power (kW) used. The system which is capable of measuring thrust, can provide data for the accurate engine power, linking it to your flow data for specific fuel consumption (SFOC). The data will also give you the shaft power/thrust ratio for your drive and propeller. Datum Electronics can provide all key elements for ship performance monitoring of your vessel:
  • Shaft Power
  • Shaft Thrust
  • Fuel Flow – (with the help of a Krohne flowmeter)

What Can a Marine Shaft Power Meter provide?

A shaft power torque meter accurately measures the power transmitted through a shaft, this enables you to measure the actual power that an engine is delivering to the propeller or generator. The Shaft Power and Torsion Meter System is an essential tool to help in the reduction running costs from:
  • 1 Fuel Saving
  • 2 Improved Maintenance Scheduling
  • 3 Equipment Protection
The same system will provide data to assess the value of new equipment and operating procedures
  • Changes to Operation
  • Changes to Fuel Types
  • Changes to Hull Coatings



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