Propulsion Dynamics (Long Beach, California) will present a paper at the Marine Coatings conference associated with the Paint and Coating Exhibition (PACE 2006) to be held in Tampa, Florida (January 29 through February 1, 2006). The paper will focus on the results that Propulsion Dynamics has achieved with its CASPER hull efficiency analyzing service on over 25 vessels in North America. The types of vessel that have been under propulsion surveillance by CASPER include tankers, containerships, and cruise liners. They have included ships of different ages and hull forms; those with various coatings, including CDP, SPC and Silicon coatings.
For these ships, the performance penalty due solely to fouling was observed and plotted in ‘real-time’ and then utilized by the ship owner as an analytic tool to compare efficiency and cost-benefit of different types of hull coatings and determine economically optimum cleaning intervals. Results indicate that operational hull efficiency cannot be deduced solely from figures published for the type of coating. Hull efficiency is affected by the vessel’s treatment in drydock, time out of dock, time in port, loading conditions, service speed, port water contamination, and water temperature.
To implement the CASPER service, the ship is only required to submit one weekly datasheet via the Internet. The datasheet gives the vessel’s draft and trim, the wind and sea conditions, and the power delivered to the propeller, among other common variables similar to a noon-report. Since this information is already available on the ship, no new equipment or software is required. CASPER employs an advanced hydrodynamic method to calculate the true speed of the ship through the water, and normalizing figures for wind, waves, sea current, and water temperature and salinity from submitted performance data. Fundamental to the analysis is the accurate measurement of propeller revolutions; the power delivered to it and its design characteristics. Using this information, CASPER analyzes the effect of hull coating efficiency for vessels in service against the performance of the vessel with a clean, smooth hull found at sea trials.