What defines a vessel restricted in her ability to maneuver?

Answer: B — The nature of her work restricts her maneuverability

A vessel restricted in her ability to maneuver is defined by the nature of her work, which imposes limitations on her ability to navigate freely. This means that when a vessel is engaged in specific operations such as laying mines, underwater work, or conducting search and rescue operations, its maneuvers may be constrained by the tasks it is performing. In contrast, the other choices do not accurately describe the concept of a vessel restricted in her ability to maneuver. A vessel sailing in open water can usually navigate freely and is not necessarily restricted. The length of a vessel does not determine its maneuverability; vessels longer or shorter than 20 feet can both be fully capable of navigating without restrictions. Finally, a vessel without an engine could potentially be operated using sails or other means, and would not inherently be restricted in her ability to maneuver, as this condition is not defined solely by the presence or absence of propulsion. Thus, the correct answer captures the essence of the definition based on the operational context of the vessel.