Results from the 2021 biofouling test campaign

Here we present some highlight from the 2021 biofouling test campaign.

The mean force measured for the triplicate samples in the loadcell of the test rig during a cleaning stroke has been compiled for the scraping intervals in this study. This is presented in figures below for the two test sites in Portugal and Sweden.

Overall observations:

• As intuitively expected, weekly interval was the required the lowest force during scraping and was easiest to clean.

• Clear difference in cleaning force required between weekly and triweekly cleaning interval throughout the exposure at both sites.

• More variation from cleaning force needed from week to week at the Swedish test site, which could origin from varying biofouling pressure during the season.

• No clear significant difference in force requirement during cleaning for biweekly and triweekly cleaning interval based on the overlap in error-bars. True for both sites.

• Independent of the cleaning interval used, the sample rods were completely cleaned from biofouling seen by the naked eye.

Here we present some example pictures of samples for the different intervals in Portugal and Sweden. One can clearly see a difference in appearance depending on the interval. Longer time between cleaning give more fouling on the sample rod. At the Swedish site, the number one foulant were barnacles and they grew in number and size from weekly to triweekly interval. The samples with no cleaning for 12 weeks (Duodecweekly) showed tubeworms and incrusting bryozoans at both sites, and in Sweden also some mussels. The longer you wait until cleaning, the more time you give macrofoulants to establish on your surface.