The project’s primary objective is to develop a test method (including an evaluation device – cleaning tool test device design funded separately) to quantify the impact of underwater hull cleaning tools on paint thickness and thus service life. The test method will also allow the measurement of environmental inputs during cleaning including biocide release (copper and zinc) and solids/particulate loading.

The technologies to be evaluated are three-fold; cleaning tools and commercially-available antifouling hull coating systems, and a device to enable the evaluation of both the impact of the cleaning tools on the hull coating systems and the release of copper and zinc. The innovative technology development encompasses the evaluation device (cleaning tool test device design funded separately), which will simulate the application of cleaning tools to painted surfaces under field conditions, including brush forces, and rotation and translation rates. The tools comprise the equipment currently used throughout the US Navy (and to some extent, the Department of Defense [DoD]) to carry out in-water cleaning of ship hulls. Antifouling hull coating systems will include a copper-containing ablative system that has been in use in the DoD for more than 25 years, a copper-free ablative system with an alternative biocide suite that is currently being qualified for extended service on DoD vessels, and a self-polishing antifouling system identified as being of high interest to the DoD and which is the subject of on-going testing effort. The project will demonstrate the utility of the device for quantifying durability of antifouling coatings subjected to cleaning, and the release of copper and zinc as a function of the cleaning process.

This project provides standardized methods to assess the effect of cleaning on underwater hull coatings. Air and water quality are negatively impacted by the accumulation of biofouling on ship hulls, and with the mitigation of biofouling by the use of a combination of underwater hull coatings and in-water maintenance (hull cleaning). Successful execution of this project will close critical knowledge and data gaps associated with the in-water cleaning of antifouling coatings, including environmental inputs and impact on coating service life as a function of frequency of cleaning and the types of brushes used to carry out the cleaning. Without this work, the DoD will remain unable to accurately predict coating system service life, determine if increasing the frequency of hull cleaning represents a viable strategy for improving fleet-wide fuel efficiency, predict environmental inputs associated with any change to the current cleaning strategy, or respond to ever-tightening environmental regulations addressing biofouling control.