Question 40 CEL01 - Chief Engineer - Limited

The Correct Answer is C ### Why Option C is Correct Option C states that the capastic epoxy "prevents shorting of the anode current to the hull and aids in a wider current distribution to the hull." This is the primary function of the capastic layer (often called a "header layer" or "anode shield") in an Impressed Current Cathodic Protection (ICCP) system installation. 1. **Prevents Shorting:** The ICCP anodes operate at a positive potential relative to the steel hull. If the anode were mounted directly onto the steel or if the current immediately flowed into the hull near the edges of the anode, it would create a direct, localized short circuit. The thick capastic epoxy acts as a dielectric (insulating) barrier between the anode assembly and the adjacent steel hull, forcing the protective current to exit the face of the anode, rather than bleeding off the sides. 2. **Wider Current Distribution:** By forcing the current to exit the primary face of the anode and preventing localized current flow immediately surrounding the anode mount, the capastic layer ensures that the protective current spreads out over a wider area of the hull, maximizing the efficiency of the cathodic protection system. ### Why Other Options Are Incorrect **A) It protects the anode from impact with foreign objects.** Incorrect. While the anode itself is often recessed or covered with a fairing (which may use epoxy), the capastic layer described here is specifically the insulating shield *under and around* the anode base. Its primary function is electrical insulation and current path management, not impact protection. **B) It raises the anode off the hull so as to improve the range of the anode current.** Incorrect. While the capastic layer does provide thickness, its function is not to increase the "range" of the current by elevation. The range (or "throw") of the current is primarily determined by the potential, size, and location of the anode relative to the water environment, not the few inches of epoxy base. The main purpose of the epoxy base is insulation (C), not elevation for performance gain. **D) It protects the hull coating from excessive current.** Incorrect. The capastic layer prevents excessive current *flow directly next to the anode*. However, the ICCP system itself is designed to provide cathodic protection which, if properly controlled, will not damage the hull coating (which is already a primary layer of corrosion protection). While preventing localized high current density (which could potentially damage localized coating), the primary function of the capastic material is to manage the current path for efficiency and prevent electrical shorting, not generally protect the coating system.