Fuel is expensive – safeguarding is needed.

Essberger checks the agreements made between the shipyards and the suppliers, for example the manufacturer of the main engine, before the taking over of the ship for sea trial. The charterer confirms the assurances of the charter party in sea service. Disagreements can lead to tensions that sea transport providers like Essberger would like to avoid as this can hinder positive collaboration with shipyards and charterers. In order to make possible a more objective discussion between the contractor and the crew, the greatest requirement is on the proof needed in terms of the agreed level of ship performance, and this burden falls on all involved parties. The most important question for the charterer regarding the profitability of the shipping trade is this: How high will the daily use be in regard to the charter party for a certain speed?

The »Charter Party« figure gives an answer to this question, represented as a green curve. This green base line curve presents the fuel consumption of the main engine (ME mt/day) depending on the speed (SOG [kn]). For example, for 12 kn a usage of about 15 metric tons per day can be expected. From the measured value cloud an actual usage of about 13 mt can be seen.

If in this reporting values are taken from diagrams, that serves as the explanation. The values are naturally much more precise in terms of monitoring if they are selected with the mouse.

The charter party base line curve is derived from two additional measurement curves: the speed-power curve and the SFOC-power curve.

The speed-power curve comes from the ship builder agreement and answers the question as to what engine capacity is needed to achieve a certain speed. For example for 12 kn, just over 3,000 kW are required; the data cloud shows approximately 2,700 kW for 12 kn.

The SFOC-power curve is provided by the engine manufacturer and sets out the specific fuel oil consumption (SFOC) depending on the engine output. For 2,700 kW, the cloud shows a value of 182 g/kWh, a number that is about 3% over the base line curve (about 176 kWh), thus lying within the 5% tolerance of the chartering party.

Let’s perform a short and informative calculation: 182 g/kWh * 2,700 kW = 491,400 g/h = 11.8 mt/day. This value lies below the charter party agreement of 15 mt per day.

This Figure shows daily average measured usage value for the main engine (M/E running) of 11.95 mt per day using a KRAL flowmeter. This is not at all far off the 11.8 mt per day calculated value that one could arrive at by simply looking at the diagram.

The graphics make possible a simple overview of the past and current performance using coloured curves: the green base line curve is the agreed optimal value, the blue curves and points represent the values reported by the crew in the vessel’s noon report.

The John T. Essberger company is very satisfied with the results of its investment in the ships Swakop, Zambesi and Selinda. Charter party deviations are easily recognised. This creates an awareness of fuel consumption onboard – the decision makers onboard the ship are made aware of the impacts of their actions on the consumption of bunker and cylinder oil. A claim concerning consumption can be justified, for example in cases of bad weather or unnecessary loads. A legitimate claim can be resolved through targeted service, if for example the measured values (in yellow) are far from the desired values. Combined measures reduce bunker costs for chartering by between 3 g/kWh and 5 g/kWh, increasing competitiveness.

Ship performance monitoring requires precisely measured values.

Measures to improve ship performance are monitored through the checking of fuel consumed. Ship performance monitoring is mainly a complex matter of fuel measurement. In the fuel consumption measurement, the most important factors are the following:

  • Speed over ground (SOG).
  • Speed through water (STW).
  • Fuel consumption clock.
  • Shaft power meter, for the assessment of any changes in the engine or the ship itself.

Engines and burners are supplied via ring pipelines. A circulating flow of fluid serves to cool the fluids that are heated by the engine and burner, thus avoiding the outgassing of more volatile content; this could lead to unwanted gas pockets. In addition, this pipework concept ensures that for rapid changes in load, a sufficient quantity of fuel and lubricant is on hand. The volume of circulating fuel in normal service is three to four times the amount utilised by the main engine. For slow steaming or when idling the usage drops, and correspondingly the circulation rate climbs by a factor of 20. Ship performance monitoring is down to accounting for difference in what flows in and what flows out.

The figure illustrates this principle of a balanced differential measurement. KRAL Flowmeters are installed in the feed pipe and the return pipe. A KRAL BEM 500 electronic unit calculates the fuel consumption difference and accounts for specific in-service conditions such as fuel backflow and temperature differences. The usage values, adjusted for error, are passed on to the performance monitoring system.

Get more information about KRAL fuel consumption measurement here >>

Thomas David comments: “The distinctive feature of KRAL is the fact that the amount of circulation is measured and so a reliable accounting is possible.”


Diesel & Gas Turbine WORLDWIDE 11 2014



KRAL AG | Bildgasse 40 | Industrie Nord | 6890 Lustenau | Österreich

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