The metal constructions located before the water undergo two types of the corrosion: galvanic and the so-called “corrosion from the stray currents”.

Galvanic corrosion is the electrochemical reaction between two or more different (or different) metals. Different, because so that the reaction would begin, one it must be more chemically active (or less stable), than of another or others. When the discussion deals for the sake of the galvanic corrosion, then is intended electro-exchange. All metals possess electric potential, since all atoms have the electrons, whose motion is electricity.

The galvanic corrosion of more reactive metal begins at that moment when two or more than component from the different metals, that have the mutual contact (because of the usual contact or by means of the conductor) they are placed beside the liquid, which conducts electricity (electrolyte). Electrolyte it can be anything, with exception of chemically pure water. Not only salt sea, but also ordinary water from under the crane because of the presence of mineral substances is excellent electrolyte, and with an increase in the temperature its electrical conductivity only grows (for this reason hull of the ship, which are exploited before the hot climate, noticeably more down attackable, than in the North Sea).

First sign of galvanic corrosion - inflation of paint beyond the surfaces, situated lower than the water line, that is begun usually on the sharp faces, and formation on the bared metal of whitish powder-like attack. Then noticeable deepenings begin to be formed beyond the surface of metal - as if someone gnaws out from it piece above the piece. The galvanic corrosion of the underwater parts of the suspension motors and angular columns - or of any aluminum parts of the boat - it considerably accelerates the presence of components through the stainless steel, such, as screw propellers, trim tabs (especially if they “are grounded” down the engine), the units of remote control. Specifically, on them depart the electrons of aluminum components. Another reason, capable of accelerating the process of galvanic corrosion - this is the decrease of the effective area of anodic protectors. Even without the presence of the stainless steel the located under water aluminum components nevertheless undergo the action of galvanic corrosion - although not so intensive as with the contact with another metal. With the presence of electrolyte on the majority uniform, like, metallic surfaces nevertheless are formed the tiny anodes and cathodes - before those places, where the composition of alloy is heterogeneous or there are outside impregnations or admixtures - for example, the particle of metal based on the forms or the dies. Another reason for galvanic corrosion - connection to coast electric brush. In this case the aluminum underwater part of your motor or column by means of the grounding conclusion is connected down the underwater parts of other boats and it becomes the part of the enormous voltaic battery, connected for the sake of the coast metal immersed before the water. In this case not only on your boat, but also on the adjacent the corrosion considerably is accelerated.

You learned, on that capable galvanic corrosion with the use of an electric potential of metals themselves. Represent that it will be, if we add still electricity! Occur similar can when the metal, across which flows the electric current, to place beside any grounded reservoir (beside the river, the lake, sea, ocean - without the difference, not on account perhaps that glass aquarium). The current through the water will be fixed beside the earth. The consequence of this will be intensive corrosion before that place, where occurred “breakdown”. In the worst case the same aluminum underwater part of the motor can be destroyed literally at the point of several days. This variety of corrosion differs from galvanic, although nature in them one. Galvanic corrosion is caused as far as the connection of two different metals and occurs due to a difference in their electric potentials. One metal comes out before the role of the anode, another - before the role of cathode. Here electric current falls on the underwater part of the boat from the external source and through the water departs down the earth. Stray currents can be caused not only as far as external, but also internal sources - by short circuit before the network of boat, poor insulation of installation, as far as gotten slightly wet contact or incorrect connection of any element of electrical equipment. The most common external source of stray currents - coast network of power supply. Boat with the internal source of stray currents (for example, because of the damage to isolation of one of the wires) can become the reason for the intensive corrosion of the set of the adjacent boats, connected down the same coast electric brush, if they ensure better grounding. Current in this case is transferred down other boats by means of all of the same “third” ground wire. Much more elusive - but potentially more dangerous - the case of stray current corrosion can occur Beza any problems with the electrical equipment (and your boat, and adjacent). Let us assume that you return down the stand after output on the water, are connected up down coast source in order to recharge storage battery, and you quietly depart home - automatic charger auto will open the loaded battery. On Monday on the proximity with your boat large steel launch moors (with the ragged and scratched paint). His owner also is connected down coast network and also leaves its vessel as far as several days. Electrical battery is ready - large steel housing and the small underwater part of your motor, connected by ground wire. Depending on their dividing distance, differences of sizes and time, which your neighbor decided to conduct on the shore, beside the following output you can reveal that the underwater part of your motor either is simply covered for the sake of whitish attack or it was destroyed almost completely.

Down this form of corrosion are subjected many metals, and in particular - the stainless steel. “Slot” in this case - these are space under all possible deposits (sand, silt so forth), under the plastic washers, by felt padding and so forth - in other words, the place, from which the moisture fallen there cannot find way out and where stagnation zone was formed. The stainless steel - this is alloy on the basis of cast iron, into which enter chromium and nickel. It does not rust because of the thin film of the oxide of chromium resultant beyond the surface of article. In the absence oxygen oxide layer is destroyed, and the stainless steel is covered for the sake of rust not worse than the usual. In other words, “[nerzhaveyka]” does not rust only until there is a access of oxygen. Before “the slot”, where the moisture is practically deprived of oxygen, this variety of steel loses its properties. Simplest method to avoid this variety of corrosion - to limit the access of moisture before “the slot”, to in time move away the generatrix of deposit and to ensure a good ventilation of similar places.

One of the primary tasks of paints for painting of vessels, metallic and concrete constructions, which are found before the water, is the guaranteed guarantee of corrosive protection of all metalware, parts of the board, the mechanisms, which enter beside the contact with the water and the rest for the realization of this task specialists propose not only high-quality paints, but also technologies of paint and varnish coat.