Question 68 GLI05 - Master or Mate of LT 200 GRT

The Correct Answer is B. The most important feature of the material used for making the binnacle of a standard magnetic compass is that **it must be nonmagnetic** (Option B). The binnacle houses the magnetic compass and often contains the compensating magnets (flinders bar, spheres, etc.) used to counteract the vessel's magnetic interference. If the material of the binnacle itself were magnetic, it would introduce its own magnetic field, thereby causing deviation errors in the compass readings, making accurate navigation impossible, and potentially interfering with the delicate compensation process. Therefore, eliminating magnetic influence is the primary structural requirement. Here is why the other options are incorrect: * **A) It must be corrosion resistant:** While desirable, especially in a marine environment, corrosion resistance is a secondary engineering consideration. A highly corrosion-resistant but magnetic material would still render the compass useless for accurate navigation. The primary requirement is accurate function, not longevity. * **C) It must be weatherproof:** Similar to corrosion resistance, being weatherproof is an important practical consideration for protecting the compass and its internal components from the elements. However, many materials are weatherproof (like steel), but if they are magnetic, they cannot be used for the binnacle. Functional integrity (non-magnetism) outweighs environmental protection. * **D) It must be permanently affixed to the vessel:** The binnacle must be securely fixed to the vessel (usually bolted to a deck pedestal) to maintain its alignment relative to the ship's centerline. However, this describes the installation method, not a fundamental material property. The material itself could be used for other purposes, but the nonmagnetic characteristic is mandatory for the specific application of housing a magnetic compass.