To reduce the possibility of rupture due to freezing, all A/C overboard discharge lines above the water line shall be self-draining within what distance of the hull?

The correct answer is that all A/C overboard discharge lines above the water line must be self-draining within a distance of 6 inches from the hull to effectively mitigate the risk of freezing and potential rupture. This specification is rooted in the need to prevent stagnant water from remaining in the discharge lines, which can freeze in cold temperatures.

By ensuring that the discharge lines are self-draining within such proximity to the hull, any residual water is allowed to flow out of the lines instead of pooling, reducing the likelihood of ruptures caused by ice expansion. The 6-inch requirement strikes a balance between effective drainage and practical installation in various marine environments, helping maintain the integrity of the vessel's plumbing system and ensuring safety.

In marine applications, where temperature fluctuations can be severe, adhering to these standards is crucial for operational reliability and safety, thereby supporting the overall performance of the vessel.