TBT  (tributyltin) is a chemical material which is used as biocide in the antifouling paint formulation which is applied to the hull of the ship since to keep the marine fouling such as barnacles, algae and others from attaching to the hull.

This fouling affects the speed of the ship and will damage the paint film.
Long back, people used the TBT antifouling paint which had good properties against marine fouling but with researches on the marine environment and the new regulations on this subject it was found that the TBT is extremely toxic to the aquatic life.
It is an endocrine disrupting chemical that causes severe reproductive effects in aquatic organisms. In addition, recent studies show that exposure to TBT makes oysters very susceptible to infection and death from exposure to pathogens.
This material is globally banned to be used with clear regulations: Regulation (EC) No782/2003 of the European Parliament and of the council of 14 April 2003 on the prohibition of organotin compounds on the ships.
As from July 1, 2003, organotin compounds which act as biocides in antifouling systems shall not be applied or reapplied on ships.
Any new ship flying the EU flag after July 1, 2003 has to be TBT free.
This means that TBT free paint has to be used from the beginning.
Ships entitled to fly the flag of a member state as from July 1, 2003,and whose antifouling system has applied, changed or replaced after that date, shall not bear organotin compounds which act as biocide in antifouling systems on their hulls or external parts and surfaces, unless they bear a coating that forms a barrier to such compounds to prevent them leaching from the underlying non- compliant antifouling systems.All of these details and other special cases were studied on the regulation.
With these, Al-Jazeera paints successfully produced different types of antifouling paints and became the first Saudi company in the Kingdom to be awarded TBT-Free certificates for its full range of Jaz antifouling from Germanischer Lloyd/Germany.
CORROSION OF STEEL ON SPLASH ZONE AREA: The steel construction in the marine environment is exposed to severe conditions such as corrosion and rust.
Corrosion of steel takes place only in an aqueous environment - consuming oxygen from atmosphere - and only when effective catalysts such as chloride ions are present.
Hence, the steel construction in the sea must be protected by different application, looking forward of the proper protection to avoid that and for long lasting of the construction lifetime, for that we can divide the construction to two parts: A) Immersed part; B) Above water line.
Part A is protected by cathodic protection.
Cathodic protection: Two types of this system available
1) Sacrificial Anode: using anodes of either coating contain zinc or magnesium metal that corrodes in preference to the primary
2) Impressed Current: Using anodes on the steel supplied with direct electrical current from battery or DC generator.
Protection is well designed for steel structure in marine structure like offshore drilling platform or petroleum pipe lines but because of (ebb & flow) phenomenon certain area of the steel structure will be temporary out of the water and no more cathodic protection since no electrolyte solution ( media). The splash zone area is the expression for this area which must be protected properly.  
How to protect splash zone area?: The proper protection for this area depends on paint system which can be applied, fully cured under the water and the excellent adhesion and protection properties.
Jaz Underwater Epoxy: Al-Jazeera company successfully developed this product which is based on solvent free epoxy polyamide to protect steel from corrosion and to act as a barrier against corrosion reactions and with many features :
1) Can be applied and cured under water.
2) Cathodic disbondment resistance.
3) Excellent adhesion on steel and concrete surfaces.
4) Excellent corrosion and abrasion resistance.
This is a high performance coating due to its hardness, durability and excellent adhesion and recommended to use on new construction as well as maintenance.