Identifying Alternative Strategies for Controlling Biofouling on United States Coast Guard Sector San Juan Vessels

Sponsoring organization: United States Coast Guard

Team members: Garrett Brogan (Chemical Engineering ’17), Nicholas Dalton (Biomedical Engineering ’17), Sean Fallon (Biomedical Engineering ’17)

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Executive Summary: Biofouling is the accumulation of marine organisms on surfaces submerged in the ocean (Cao et al., 2010). It oftentimes affects the hulls of ships and causes significant drag and thus increased fuel consumption (“Waterborne Underwater Hull Cleaning of Navy Ships”, 2006). Sector San Juan of the United States Coast Guard has faced significant economic losses in fuel costs (Robert Hemp, personal communication, 2015). This is due to the drag induced by biofouling. Due to budgetary constraints, Sector San Juan is only able to provide one in-water hull cleaning per year before having to pull from other budgets around the base (Robert Hemp, personal communication, 2015). One cleaning is insufficient, however, as the biofouling accumulation in Sector San Juan is so aggressive that ships will experience up to a 20% loss in speed in an unacceptable time frame (Robert Hemp, personal communication, 2015).

Our team was tasked with looking at the current hull cleaning schedule and finding where it could be improved in order to save the most money for the Sector in fuel savings. Early in the project we discovered that some of the data necessary to make these schedules was not presently available, so we created a data collection and analysis protocol which recommends how data should be collected, organized, analyzed, and then compared to create the improved hull cleaning schedules. In addition to this, we researched anti-fouling coatings and hull cleaning techniques to make recommendations for the application of a more ecologically appropriate anti-fouling system and alternative hull cleaning technologies for the Sector San Juan vessels.

Methodology:

To accomplish the goal of reducing the economic impact of biofouling in Sector San Juan, we created three primary objectives. They are as follows:

1. Determine an effective hull cleaning interval that reflects the needs of the Sector.
2. Evaluate the effectiveness of current standardized anti-fouling coatings set by the United States Coast Guard and research alternative technologies that may provide better defenses against biofouling.
3. Assess the present cleaning tools and techniques employed in Sector San Juan to combat biofouling accumulation and if appropriate, propose alternative tools and techniques.

To address the first objective, we completed several steps. First, we identified what the current hull cleaning schedule is, and evaluated its effectiveness. Second, we identified what aspects of a ship’s performance (engine performance, fuel consumption rates, etc.) were taken into greatest consideration when justifying a hull cleaning. Third, our group assessed how the biofouling issue in San Juan affects the aforementioned performance aspects of a ship. Finally, we searched for data relating to these reasons, such as biofouling accumulation, top speed reduction, distance traveled by each vessel, and consumed fuel amounts. Once these steps were completed, we were able to correlate the factors affecting a vessel with the performance losses experienced. This assessment would then lead to identifying when a vessel should be cleaned in order to avoid these certain performance losses.

To acquire all of this information, we reached out to:

• Commander (CDR) Hemp – the head of the Sector San Juan Logistics Department
• Sam Alvord – the head of the Coast Guard Office of Energy Management
• Several Commanding Officers (COs) and Engineering Petty Officers (EPOs) of the vessels on base.

For the second objective we identified the current hull coating used in Sector San Juan. Following this, we sought to understand the mechanisms by which the coating combats biofouling and how successful it was in the Sector. Furthermore, we researched other coatings available on the market to find one that could better serve the needs of the Sector.

We completed the last objective by identifying the current techniques used by the contracted divers and researching academic literature for proven hull cleaning methods. We then compared our findings and put forth recommendations.

Findings:

We found that there are four sets of data needed in order to be able to effectively create a new hull cleaning schedule:

• Biofouling Accumulation – Necessary to see how biofouling accumulation accelerates on vessels in Sector San Juan. As harder biofouling begins to accumulate, the difficulty to remove it from the hulls will increase (Commanding Officer “A”, personal communication, 2015).
• Speeds and associated RPM – Can be used to illustrate how a ship’s operating speeds are impacted over the time that biofouling accumulates. To achieve a vessel’s top speed, an engine needs to input more work which could lead to engine breakdown.
• Fuel consumption (burn) and associated distance travelled – Needed to correlate biofouling accumulation to the increase in fuel consumption (and thus increased costs to operate the ships). This is important because it allows for comparing new schedule options on the basis of potential money saved for the Coast Guard, and will be the definitive data set in deciding upon new schedules.
• Gallons per hour consumed – This data point is an alternative for calculating fuel money saved, as it is more specific and can be correlated to the different speeds a ship travels at.

We found that the anti-fouling paint currently employed on the vessels in Sector San Juan is a copper ablative biocidal anti-fouling paint (more specifically International Interspeed BRA 640) (Commanding Officer “A”, personal communication, 2015). This type of coating (ablative and copper biocide) is unfit for the conditions of San Juan.

• Copper is at risk of being legally banned for use in anti-fouling due to the damage it does to marine life (Kaznoff & Rudroff, 2000).
• Ablative paints intentionally wear down and fall off the hull easily (Commanding Officer “A”, personal communication, 2015). This is unsuitable for San Juan because the hulls undergo more frequent cleanings in San Juan than in most other USCG Sectors (Robert Hemp, personal communication, 2015).

Current in-water hull cleanings are very effective at removing macrofouling (the hard, easily visible biofouling), but do not remove the microfouling according to a diver contracted by the Coast Guard to clean hulls (Personal communication, 2015). Microfouling is important to remove, because without it the macrofouling cannot attach well (Cao et al., 2010).

• Should the frequency of in-water cleanings per vessel increase, it would be wise to have this microfouling cleaned off as well, so that for the next cleaning, the macrofouling would be less abundant and attached less strongly. This would reduce the time needed to clean the hull and make the work to do so easier.

Our findings and potential recommendations do not put the divers contracted by Sector San Juan at risk of losing in-water hull cleaning contracts. None of our findings support the need, benefit, nor possibility of reducing the number of in-water cleanings conducted within the Sector.