In the context of vessel construction, what does the term 'sheer' refer to?

The term 'sheer' in vessel construction specifically refers to the upward curve of the deck line from the stern to the bow. This design feature is essential for both aesthetic and functional purposes, as it affects the vessel’s performance in various sea conditions and influences the drainage of water off the deck. A well-designed sheer helps to prevent water from coming on board during rough weather and enhances the vessel's overall lines, contributing to its beauty and efficiency.

Understanding sheer is crucial for those involved in naval architecture and marine engineering, as it impacts how a vessel interacts with water, its stability, and its handling characteristics. The other options pertain to different aspects of ship design: the angle of the keel relates to the ship's stability and maneuverability, the width of the hull addresses stability and cargo capacity, and the shape of the bow affects hydrodynamics and performance, but none of these define 'sheer.' Thus, the focus on the upward curve of the deck line is what solidifies the correct interpretation of the term.