Proactive biofouling removal led to "significant" improvements in emissions and fuel efficiency for two Hapag-Lloyd container ships, with repeated hull cleanings helping reduce water resistance and prevent marine organisms such as algae, slime and other debris from re-accumulating on the hulls of each vessel.

Hapag-Lloyd tagged hull cleaning service Shipshave to determine the benefits of consistent biofouling removal over a 17-month period on an 8,749 twenty-foot-equivalent (TEU) container carrier and an 18,800 TEU carrier. The study found that one of the ships saw a "staggering" 16% improvement in fuel efficiency — equal to removing the emissions of nearly 5,000 fossil-fuel-driven cars — while the other vessel achieved a more modest 5% improvement. 

“The findings of this case study emphasize the critical role of minimizing biofouling in reducing greenhouse gas emissions from shipping," said Dr. Uwe Hollenbach, a senior principal consultant for maritime classification society DNV. "Regular or proactive hull cleaning remains one of the most effective strategies to achieve this goal."

That's consistent with guidance from the International Maritime Organization (IMO), which states that large accumulations of biofouling on vessels can have a "severe impact" on fuel costs and emissions.

The IMO says that proper biofouling management can also help reduce the risk of transferring invasive aquatic species, and improve overall energy efficiency.