What signal means you are "Underway"?

Being "underway" refers to a state in which a boat is not anchored, adrift, or made fast to the shore. The defining characteristic of being underway is that the boat's engine is actively running, and it is not stationary due to anchoring or being tied to a dock. This means the vessel is capable of navigating through the water.

The other conditions described in the other choices involve positions where the boat is not actively maneuvering across the water. When the anchor is lowered and secured, the vessel is essentially at rest and not moving. Similarly, if the boat is moored at a dock, it is still and not clinging to the definition of being underway. Lastly, while having sails up and filled with wind implies that the boat can move, if it is not in motion with respect to its operational conditions, it is also not classified as underway.

Thus, the correct understanding of "underway" is that the vessel's engine power is engaged, and it is actively navigating the water, ensuring compliance with boating regulations and safety.