Auxiliary steering shall be sufficient for steering at what speed?

The correct choice is navigable speed because auxiliary steering systems are designed to provide sufficient control of the vessel under conditions where primary steering might fail. Navigable speed is typically defined as the speed necessary for a vessel to effectively maneuver in various water conditions and maintain safe operations. This includes ensuring that the vessel can be navigated safely even if the primary steering fails, allowing for proper control during both docking and open water scenarios.

In the context of auxiliary steering systems, this is crucial to ensure that a vessel can still be operated safely and effectively in situations where speed may fluctuate, and the ability to respond to navigational needs remains uncompromised. This level of control is essential for meeting safety regulations and operational protocols within marine operations.