Fouling increases the roughness of the vessel's hull and as a result the fuel consumption and thereby the CO2 emissions also increase. Another challenge is the potential risk that invasive species are tranfered to different ecosystems thereby affecting the biodiversity. Therfore fouling needs to be controlled.
To prevent fouling, the hull is coated with antifouling paint. Conventional paint contains heavy metals such as tin, copper, lead and arsenic, all of which release toxic biocides into the water. They may also contain other substances that are harmful to marine life.
Toxic tributyltin (TBT)
In 1974, TBT was introduced which revolutionised the antifouling market with its performance. This self-polishing coating resulted in major improvements in both fuel consumption and service life compared to earlier coatings. TBT therefore quickly became a very cost-effective coating. However, we now know that TBT has clear adverse effects on marine life. TBT is responsible for the disruption of the endocrine system of marine shellfish, for instance leading to the development of male sex characteristics in female marine snails. TBT also impairs the immune system of organisms and consequently shellfish develop shell malformations after being exposed to extremely low levels of TBT in the seawater. That is why the phasing out of TBT was a very important step for reducing marine pollution. TBT is now forbidden.
Read about our solutions within antifouling
|
TBT is a general term for organotin compounds. In antifouling it is usually the specific substance TBTO which is referred to.
TBTO
C24H54OSn2
- Also called Tributyltin oxide
- Androgen effects which leads to endocrine effects on marine life
- Non-degradable, tin older than 10 years has been found in sediment
|
|
Copper
Cu
- Toxic to fish, mussels, crustaceans and algae in small doses
- Bio-accumulative, non-degradable |
|
Irgarol
C11H19N5S
- Also called Triazine
- Very stable
- Bio-accumulative
- Toxic to algae – inhibits photosynthesis
- Very toxic – booster biocide
|
|
Diuron
C9H10Cl2N2O
- Toxic to fish
- Highly toxic to aquatic invertebrates
- Carcinogenic
- Persistent
|
|
Zineb
C4H6N2S4Zn
- Also called Zinc carbamate
- Toxic to bacteria
- Carcinogenic
- Very toxic – booster biocide
|
|
Zinc pyrithione
C10H8N2O2S2Zn
- Forms degrading products
- Very toxic to aquatic organisms
- Faster bio-degradation than irgarol, zineb and TBT → acceptable substitute
|
Read about our solutions within antifouling