Artwork by Gil Mares ©2009

Propulsion Dynamics offers break-through methods of service performance analysis, based on state of the art theoretical and empirical mathematical models, developed from over 500 ship-years experience.

Most performance monitoring systems are based on data-logging (base-lining) methods that are unable to directly quantify the effects of fouling of the hull and propeller on ship performance.  They typically involve reliance on some base-line performance of the vessel (such as sea trials, which in themselves may not reflect the true performance of the vessel in service), and they require recording voluminous amounts of data, not to mention correct technical interpretation of the data.  Physical inspections of the hull and propeller (including roughness measurements) do not provide a reliable metric with actual speed / fuel losses, nor are they able to be utilized for correlation studies. 

In the CASPER service, each ship is treated in an utterly individual manner, including the adjustment of up to 100 coefficients in each mathematical model, in order to create a Ship Performance model.

By recording and transmitting the performance data from the existing instruments (at specific intervals in connection with ship particulars and sea trial data of the vessel) the Shipmanager will receive reports summarizing the hydrodynamic performance of the vessel in actual operation. The data collected is fully corrected for wind, waves, sea current, draft/trim, water temperature, salinity, fuel oil quality and other variables, thus providing him with the immediate and scientific decision-support to reduce fuel consumption (reduce emissions), optimize fuel costs with maintenance costs (such as hull cleaning or propeller polishing) and analyze the efficiency of treatment in drydock as well as the economic lifecycle between the multitude of hull coating systems.

PDI has no affiliation with any coating suppliers, contractors or institutions, assuring our customers of unbiased technical opinions.

Brief Outline of Method

The true speed of the vessel through the water, which forms the basis of the analysis, is determined by an accurate measurement of the propeller torque and revolutions, in connection with the design characteristics of the propeller.  Well-known wind and wave resistance tables (ITTC) adjusted with state of the art empirical know-how are used for correcting the effects of wind and waves and mathematical models used in ship design and (model) testing are used for compensating for the draft / trim of the vessel.  Since the power delivered to the propeller is measured on any vessel in two to five different ways and the sea state is measured in three different ways, through intensive use of proprietary statistics, it is possible to state precisely, the performance of the vessel in service against the performance of the vessel found at sea trials. There is no need for commencement of data collection from the maiden voyage or drydock in order to carry out this program.

From this true-speed-through-water, we calculate the ship's "added resistance".    The added resistance is defined as the percentage by which the resistance against propulsion at design draft and design speed is increased.  It is a non-dimensional physical characteristic that translates into precise speed and fuel losses due to fouling and corrosion of the underwater surface (in relation to trial trip) and is independent of speed, weather, draft.  Customers use our data for 'beyond compliance' programs related to MARPOL, TMSA and ISO 14001 subchapter 4.5.1.

With fuel price volatility, increase demand to reduce emissions and the advent of new hull coating formulations as well as new hull cleaning techniques, our services are well received today among some of the most well respected shipowners / operators and shipmanagers.