The warm waters of the Gulf are likely to have been highly conducive to barnacle growth for the ships stuck there. File Image / Pixabay

Middle Eastern barnacles may be about to claim a significant role in the global bunker market.

While the market anticipates the impact of the Strait of Hormuz potentially reopening in the coming weeks, getting less attention is the state of the vessels trapped behind it in the Gulf for the past three months.

These ships have been idling for months in waters highly conducive to biofouling - the build-up of slime, algae and calcareous organisms like barnacles on their hulls - which is likely severely to limit their fuel efficiency when and if they start moving again.

"The Persian Gulf is one of the most biologically aggressive fouling environments in the world: extreme heat, high salinity, and elevated nutrient levels create conditions where fouling succession from biofilm to barnacles accelerates dramatically compared to temperate waters," Dr Markus Hoffman, technical director of I-Tech AB - the makers of antifouling agent Selektope - told Ship & Bunker.

"Some fouling species, such as barnacles, can only settle under static conditions — so the current situation combines static vessels with exceptionally fouling-aggressive waters, a particularly dangerous combination."

There are currently around 500-600 large ships in or near the Persian Gulf. These ships are now likely to need considerably more fuel to operate, Dr Hoffman said.

"The impact of barnacle fouling on fuel consumption can be severe," he said.

"Research shows that even 10% barnacle coverage requires a 36% increase in shaft power, and severe calcareous fouling can elevate required shaft power by up to 86%.

"These figures depend, of course, on vessel type and operational parameters such as speed — but even at the lower end, the fuel cost implications are substantial.

"In practical terms, heavily fouled vessels can see fuel consumption increase by 40 to 50% or more."

CII ratings will also be heavily affected, as well as GHG compliance costs for those operating on routes involving EU ports.

These 500-600 ships are likely to be consuming around 40 mt/day of bunker fuel on average under normal circumstances. Adding 40-50% to their consumption will increase global demand by 8,000-12,000/day, or 1.76-2.64 million mt/year on an annualised basis assuming an average of 220 days/year sailing.

That amounts to an increase of somewhere close to 1% in global bunker sales. As the majority of these ships normally operate between the Middle East and Asia-Pacific, ports like Fujairah and Singapore are likely to see most of the gain.

These ships are highly unlikely to remain in this impaired state for anywhere close to a year, but at the same time, the problem will not be resolved quickly.

"For the vessels currently stranded, the immediate priority is to inspect hulls and carry out cleaning where needed," Dr Hoffman said.

"Very few vessels carry their own proactive cleaning robots, so the alternative is to engage specialist cleaning companies — which have limited capacity and will be in high demand.

"With potentially hundreds of vessels requiring cleaning simultaneously, regional cleaning capacity will be overwhelmed.

"Owners who act earliest will minimise damage; those who wait risk a compounding effect as fouling deepens and cleaning becomes both more difficult and more damaging to the coating.

"Most of the affected vessels will need reactive hull cleaning, but performance will not return to the baseline even after cleaning.

"I expect the majority to be scheduled for dry-docking sooner than planned: repeated reactive cleaning depletes the paint film, and once the antifouling layer is gone, the hull has no protection. Dry-docking will be a necessity, not just a preference."

If ships start to escape from the Gulf from this weekend onwards, their immediate goal is likely to be to exit the region as quickly as possible and deliver their cargoes to undersupplied markets. But fixing their biofouling problem will rapidly become an economic and operational necessity.