Hull cleaning

The purpose of underwater hull cleaning is to remove biological roughness or fouling. A build-up of marine fouling can lead to increased drag, resulting in a detrimental impact on a vessel’s hydrodynamic performance and hence the relationship between speed, power performance and fuel consumption.  Fouling, particularly in the case of a prolific build-up of ‘hard or shell fouling’ like barnacles or tubeworm, can cause turbulence, cavitation and noise, frequently affecting the performance of sonars, speed logs and other hull mounted sensors.

Applicability and assumptions

Hull cleaning is applicable for all vessel types and ages. Depending on the degree and type of fouling to be removed a diver can typically clean 200-400 m² per hour of flat surfaces (less on the bow and stern areas). Similarly, a ROV is capable of cleaning 800-1000 m² per hour. The operation will be performed during normal ship stops (bunkering, anchorage, waiting for canal passage, etc.). Note that cleaning of hull is not allowed in many ports due to risk of contamination of the local aquatic life.

The potential for fuel reductions is clearly very dependent on how heavy the hull is fouled. The waters in which the ship operates will have a large impact on the effect of the measure. Waters with a high degree of fouling and algae growth will provide relatively higher savings compared to areas with less growth. Vessels that lie a lot at rest will also generally achieve higher reductions than more mobile ships, due to greater fouling rates.

Cost of implementation

The price of hull cleaning will depend on the selection between a diver and a ROV, in addition to the vessel size. Total operational cost is estimated to be in the range of $5,000 – $50,000 (USD).

Reduction potential

Depending on the degree of marine fouling, vessel size, vessel segment, operation profile and trading areas a reduction in the range of 1 – 5 % on total fuel consumption can be expected.

Other References

1. GloFouling Partnerships. (n.d.). Biofouling and greenhouse gas (GHG) emissions from ships
2. TEST Bioufouling (n.d.). The Issue
3. Adland, R. (2018). The energy efficiency effects of periodic ship hull cleaning
4. Oliveira, D.R., et al. (2020). Ship hull in-water cleaning and its effects on fouling-control coatings
5. Jotun Hull Skating Solution