The question asks us to identify the single word that means "to guide the course of a ship especially by using instruments or maps". Let's look at the options provided and understand what each word means in the context of ships.

Understanding Guiding a Ship's Course

Guiding the course of a ship involves planning and controlling its movement from one point to another. This often requires using tools like compasses, charts (maps of water areas), GPS, and other instruments to determine the ship's position and direction. The phrase emphasizes the systematic process of directing the ship's path.

Analyzing the Options for Guiding a Ship

1. Navigate

• The word "navigate" means to plan and direct the route or course of a ship, aircraft, or other form of transport, especially by using maps or instruments.
• This definition perfectly matches the description given in the question: "guide the course of a ship especially by using instruments or maps".

2. Travel

• "Travel" is a very general term meaning to go from one place to another.
• While a ship travels, the word "travel" itself doesn't specifically describe the act of guiding its course using instruments or maps. It just means the act of moving from one location to another.

3. Sail

• "Sail" can mean to travel by ship (especially in a boat with sails) or to begin a voyage.
• It relates to the movement of the ship through water, often propelled by wind power (if using sails) or just the act of being on a voyage. It doesn't specifically focus on the method of guiding the ship's course using instruments or maps.

4. Anchor

• "Anchor" means to moor a ship or boat to the seabed using an anchor, typically to secure it in a particular location.
• This is the opposite of guiding the ship's course, as it involves stopping the ship's movement and fixing its position.

Conclusion: The Correct Word for Guiding a Ship

Based on the analysis of each option, the word that specifically means "to guide the course of a ship especially by using instruments or maps" is navigate.

Navigating is the technical process involving planning, monitoring, and controlling the movement of a vessel, making precise use of charts, instruments, and calculations to reach a destination safely and efficiently.

Revision Table: Key Terms for Ship Movement

Additional Information on Ship Navigation

Ship navigation is a critical skill for safety at sea. Historically, navigators relied on celestial navigation (using stars and planets), dead reckoning (estimating position based on speed, direction, and time), and paper charts. Modern navigation heavily involves electronic systems like GPS (Global Positioning System), electronic charts, radar, and automated systems, but understanding fundamental navigation principles using instruments and maps remains essential.