Surendran Sankunny

Marine biofouling refers to the undesirable growth and adhesion of marine organisms such as barnacles, macro-algae, microbial slimes etc. on immersed structures. Tropical ocean environment teems with microorganisms, of which some adhere, both to the static ship hull and while en-route to the destination increasing roughness1. A laboratory-scale LIBS technique was used to analyse biofouling samples and its constituent common water-borne algae and bacterial species2. Biofouling composition was determined by collecting samples from marine structures and vessels and analysing them in laboratories. Biofouling characterization tests were also done such as SEM analysis. The Quanta 200 FEG Scanning Electron Microscope (SEM) was used for obtaining the SEM images. The structure of quartz crystal in the biofouling samples was also determined.

Manufacture of coatings to tackle the biofouling menace has been of prime concern for the shipping industry since industrial revolution. Even though many types of coatings exist in the market, they have not been able to wipe out the problem of biofouling completely. The proposed approach which combines both the resistance due to biofouling on ships, as well as biofouling characterization, will surely serve as a critical input for the manufacture of efficient anti-fouling coatings. Resistance simulations have been carried out for a tanker ship by Maxsurf® wherein the hull fouling effect has been accounted for by modified ITTC 1978 empirical formula considering roughness. Different draft conditions were relied upon to find out the resistance at various Froude numbers. The fouling growth conditions considered are small and medium calcareous fouling. The simulated results also have been validated by towing tank experiments, for no-foul condition, for speeds varying from 0.3 to 1.1 m/s and different drafts. The additional power requirement was determined for various loading conditions and speed ranges.

In the present study, femtosecond Laser Induced Breakdown Spectroscopy LIBS technique has been used to investigate the growth of biofouling on Fiber Reinforced Plastic (FRP) panels submerged in the Indian Ocean for various stages of growth. The coupons were suspended in the Indian Ocean at a depth of 1m at a distance of 480 m from the shoreline. The panels were recovered from the sea at regular intervals of 5, 10, 15 and 20 days. Growth of fouling panels were monitored and related with contact angle measurements. Elemental characterization conducted with Femtosecond LIBS indicated the presence of the elements Al, Ca, N, Ba, and Na. The study would help in creating a database for marine biofouling.

In the present study, LIBS spectra of biomolecules have been analyzed. The basic biomolecules considered for the analysis were Carbohydrates, Protein and Nucleic acids. It was possible to detect the characteristic emission lines of C, H, N, O, S etc. in the above biomolecules. The samples were prepared for laser ablation as biofilms on glass slides. Interference from substrate was observed in the LIBS spectra of samples. Raman spectra would also be acquired in future studies to obtain molecular information for the biomolecules.