Polyester hulls There are changes to the protective coatings in same conditions

Polyester hulls there are changes to the protective

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Polyester hulls There are changes to the protective coatings in same conditions (paintwork and/or antifouling). Steel and aluminium hulls There is degradation to protective coatings (paints and/or antifouling) and the risk of their detaching through the appearance of even blistering arising from the production of hydrogen at the metal surface; this is particularly the case with aluminium. Furthermore, over-protection promotes the establishment and proliferation of colonies of limpets (barnacles). THE CONSEQUENCES OF UNDER-PROTECTION The most feared and the best known, this consists of corrosion to metal parts, resulting in a loss of material that is sometimes dramatic. Thus, accidental electrical pollution caused by electrolytic corrosion can sink a ship at anchor in just a few weeks!
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Check the efficiency of your anodes! Ver 8.3 - © 2010+ by GPS - The information provided is non-contractual and published with all proper reserves. 14 THE CORROSIVE LOOP The corrosive loop is solely responsible for the corrosion of metal immersed equipments. It can be galvanic originated, electrolytic originated or both galvanic and electrolytic originated. GALVANIC When a link exists, deliberate or accidental between two different metals (brown circle arc), a natural current travels from cathode to anode and electrons goes the opposite way. Anode is then the metal with the lowest potential. In electrolyte (water), positive or negative ions shut the loop and carry the electric load. Metal from which current leaves loses its electrons, oxydises and corrodes (sail-drive’s carter). As electrons always leaves the more electro-negative metal, creating a new link with an even more electro-negative metal is efficient enough to protect it. It is the sacrificial anodes mission and the
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Check the efficiency of your anodes! Ver 8.3 - © 2010+ by GPS - The information provided is non-contractual and published with all proper reserves. 15 primary principle of cathodic protection: sail-drive’s carter thus becomes a cathode instead of an anode and is consequently protected. ELECTROLYTIC In a similar way, when an external deliberate or accidental current (i.e. leak), is added to the natural galvanic current, metal connected to (+) becomes anode. As it always travels from cathode to anode and electrons the opposite way, it reinforces the corrosive current of the galvanic loop: According to Ohm’s law, the more current is present, the greater is the impending danger for the sail-drive. The loss of weight obeys to Faraday’s laws 3 . Caution! In an electrolytic loop, polarities are opposite when regarding those of a galvanic loop! Overall logic is maintained. Thus, an aluminium sail-drive which potential is (-) 800 mV (without sacrificial anode) will « gain » 400 mV 3 See calculator on Galvatest web site
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Check the efficiency of your anodes!
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