What does the term 'gunwale' refer to in boating terminology?

The term 'gunwale' refers to the upper edge of the side of a boat or ship. This area is critical for the structural integrity of the vessel, as it helps to support the entire frame of the boat and is often where various accessories or fittings are mounted, such as handrails or fishing rod holders. Understanding this terminology is vital for safe boating practices, as it aids in communication about vessel components and maintenance. The other options do not accurately define a gunwale; they refer to different parts of a boat, such as propulsion systems, storage areas, or spaces unrelated to the upper edge of the vessel's sides.