Archive for month: January, 2020

The old school performance system is based on daily reporting by the ship’s crew (noon data). The intention of...

With relation to uncertainty in measurements of data it is necessary to analyse each sensor with respect to manufacture...

The data used for the performance analysis: may be with an interval i.e. 10 seconds. This interval is not...

Another method for detecting changes in a signal is based on change detection algorithms. An expected behaviour of a...

When setting up rules for removal of spikes it will be necessary to evaluate the mean and variance in...

If the ship’s performance has to be simulated under all conditions it is necessary to find a method for...

More than 20 parameters are logged through the ship’s automation system. The timestamp for the logging has to be...

When measuring and analysing the data it is desirable that the data has statistical properties that are invariant over...

The data is sampled at an interval given by the software system. According to the Nyquist sampling theorem, Jerri...

Logged parameters Data acquisition sampling rate stationarity Data transformation Data evaluation Pre-processing spikes drop-outs Analysis Statistics Dissemination

Loading conditions Draught – trim Loading – wind area Position of point of gravity Operational conditions Heading Speed through...

The logged data from the sensors on board the ship is picked up by software designed for the purpose....

Draught information is given as manual input. At departure from port the draught forward and aft is taken from...

The sea water temperature is measured at the sea chest suction on the starboard side. The water temperature at...

The bow motions are measured by an accelerometer which is of the low-frequency type and placed in the bow...

The gyrocompass measures the ship’s heading with reference to true north. The heading is used to calculate true wind...

The air temperature is measured by a thermometer and the air pressure is measured by a barometer, both placed...

The GPS gives information about the speed of the ship. The speed is measured above ground whereas the speed...

The wind anemometer is a helicoid propeller type with a vane for direction measurement. The wind anemometer is mounted...

The stabiliser fins counteract the roll movements of the ship when sailing. The stabiliser fins are fitted on both...

The rudder indicator measures the rudder angle continuously and the measuring accuracy in the range of +/- 0.5° at...

If thrust were to be measured by strain gauges the thrust measurements would be in the order of 35...

The shaft motor is an electric motor delivering power to the shaft. The shaft motor is supplied with electrical...

There are increasing economic and environmental incentives for ship owners and operators to develop tools to optimise operational decisions,...

Propeller torque is most commonly measured by strain gauge techniques. The strain gauges are placed on the propeller shaft...

Sea state Violent pitching in bad weather. Sea water temperature Rising cold water in several sea areas. Hot water...

Two sensors are installed on the ship – one in the forward section and one approx. below the accommodation....

Environmental factors influencing the speed log measurements, Litton (1998): Water clarity Measurement of the speed through water depends on...

The speed log is a crucial source for data in the performance calculation. The accuracy of the sensor depends...

During service the ship will experience an increase in hull fouling dependent on the operational conditions. Factors which influence...

An increase of underwater hull surface roughness will increase the hull frictional resistance of the ship while sailing. This...

Basic elements of a performance system are: Propeller shaft including shaft power measurement Propeller Hull including wake and thrust...

Automatic logging of data – Setting up a system where the continuously logged data are collected on disks or...

The logging of the fleet’s performance have been incorporated as a daily routine for the crews on board the...