watchstanders to fall into the habit of relying too heavily on a single source of information, whether that’s radar, the Automatic Identification System (AIS), or visual observation. Each tool is valuable, but none is complete on its own. When used in isolation, they can leave gaps, and it’s within those gaps that risk tends to build. At CME, we see the most effective mariners as moving beyond reliance on any one system. They understand how each tool contributes to the broader picture, combining them to form a clear, accurate, and reliable understanding of the situation around them. 

When I reflect on my own personal experience in the U.S. Navy Reserve and with the Naval Coastal Warfare Group, this lesson was reinforced early. In port security and escort operations, we never assumed that one system would give us everything we needed. Equipment could fail, data could be wrong, and conditions could change quickly. The only way to stay ahead of a threat was to build layers—overlapping sources of information that confirmed, supported, and sometimes challenged one another. That same mindset applies directly to navigation in the wheelhouse. 

Radar is often the starting point, but it only becomes truly effective when it is used actively. The “Running CPA” method—introduced by Capt. John Moyle and more widely known at SCI as the “Equivalent Systematic Observation” (ESO) technique—turns radar into a practical decision-making aid. By carefully watching how a contact’s bearing and range change over time, a mariner can quickly recognize whether risk is developing. If the bearing stays steady while the range decreases, the situation demands attention. That realization, made early, creates time to think, communicate, and act before the situation becomes critical. 

AIS adds another layer to the overall picture by providing insight into a vessel’s identity and purpose, such as who it is, where it’s going, and how fast it’s moving. This helps watchstanders interpret how an encounter is developing and apply the Rules of the Road—recognized navigation rules that govern how vessels interact—with greater confidence. However, AIS is only as dependable as the data entered into it, and not all vessels transmit it. For that reason, it should never be relied upon alone. It must always be verified against radar information and visual observation. 

One of the most valuable features within AIS is the use of vectors, especially relative vectors. While true vectors show how vessels are moving over the ground, relative vectors reveal something more important for collision avoidance by showing how those vessels are moving in relation to you. They make developing risk easier to recognize and help a watchstander understand how changes in course or speed will influence the situation. 

Then there are target trails, a tool that is often overlooked but incredibly powerful. Trails show where a vessel has been, turning movement into something visible and immediate. In busy or confined waters, short trails allow a watchstander to quickly recognize direction, speed, and maneuvering behavior without needing to interpret numbers or wait for calculations. Even when AIS data is missing or unreliable, trails continue to tell the story. 

Individually, each of these tools has limitations. Radar can be affected by weather or improper setup. AIS depends on human input and proper configuration. Automated tracking systems can lag or introduce errors. But when they are used together, those limitations begin to cancel each other out. One system verifies another. One fills in what another cannot provide. This is where true situational awareness is built; not from any single piece of equipment, but from the deliberate combination and assessment of all of them. 

The effectiveness of wheelhouse technology ultimately rests on the training, discipline, and judgment of the mariner behind it. When radar, AIS, target trails, and visual observation are used together as layered tools, well-prepared watchstanders gain the clarity and time needed to make sound, safety-focused decisions. At the Center for Maritime Education, this approach reflects SCI’s broader commitment to mariner safety and safe navigation, and continues to guide our work with maritime partners across the industry.