Data accuracy and reliability are vital when analysing hull coatings and planning tank cleaning said experts at Riviera Maritime Media’s Tanker Shipping & Trade, Europe virtual conference
Session panellists included Safinah Group general manager for marine consulting Carl Barnes, Safinah Group consultant Michael Aamodt and Consulex principal Consultant Terry Greenfield.
Examining ship performance and hull fouling information allows shipping companies to make informed decisions on which coatings to apply, they explained during session five of the virtual conference on 17 November.
Mr Barnes said owners need the right information from historic datasets and biofouling prevention technology suppliers as there are more than 100 products available. “Independent data analysis of fouling control product performance is key to selecting products for specific vessel trades,” he said.
If there are performance issues, these need to be identified and flagged to managers.
“Data suggests that either the current fouling control products are not performing as planned or the coatings specified are not suitable for how the vessel is eventually traded,” said Mr Barnes.
“Based on the analysis of our (Safinah Group) extensive dataset of vessel returns, the evidence to date implies that approximately 50% of vessels return to drydock with more than 20% fouling coverage on the underwater hull,” he said.
This implies more developments are needed to reduce biofouling on ships, especially those slow steaming or remaining idle.
Mr Barnes outlined the fouling challenge in his presentation as marine growth is accelerated by warm water temperatures, high periods of illumination, high nutrient levels and vessel inactivity. “The majority of fouling occurs when vessels are below 5/6 knots, and during significant static periods,” he said.
Generally, hull paint suppliers specify a minimum speed of around 10 knots and a maximum static period.
Mr Greenfield explained to attendees how data is important for supporting hull coating decisions.
“Learn from the historic data and processes that are effective,” he said, adding. “Good data should be accurate and reliable – we need to see repeatability for its reliability.”
Mr Greenfield also explained how reliable testing should be implemented in deciding suitable coatings for tanker cargo tanks because “no one size fits all when selecting coatings”.
He said owners should “use realistic and accurate testing frequently to make decisions and minimise risk” while considering the risk of contamination and permeation.
Mr Greenfield took testing for chloride contaminants as an example, as shipping is exposed to these chemicals in the marine environment. “There are processes available for removing these contaminants and some are more effective than others,” said Mr Greenfield.
Testing and data analysis is also important in identifying the effectiveness of tank cleaning, said Mr Aamodt. He focused on methanol wall-wash testing in the presentation.
He said methanol washing was used for cleaning cargo tanks as it would penetrate and remove retained cargo and then be vented out. “Now methanol wash method is, for safety reasons, banned unless the tanks are in an inert atmosphere,” said Mr Aamodt.
This made phenolic epoxy coatings not fit for purpose for traders carrying high purity chemicals and known absorbers such as styrene.
But methanol wall wash testing is still allowed and used as a small-scale analytical assessment to determine the cleanliness of tanks. “It is quick and accurate testing, but safety measures must be taken before sampling happens in the tank,” said Mr Aamodt.