Navigation is the bridge's responsibility. The Master, Officers of the Watch, and navigator manage the vessel's movement, course, and position. You are not expected to navigate.
What you are expected to understand is enough to function as an effective crew member: how positions are described and communicated, how to identify and report the location of targets relative to your vessel, and how to maintain basic awareness of where you are and what is around you. This knowledge also helps you understand operational briefings and contributes to your own safety.
- Latitude and longitude — how position is described and communicated at sea
- The clock system — how to identify and report the position of targets relative to the vessel
- Nautical charts — what they show and why they matter
- AIS — the vessel tracking system you'll see used aboard
At sea, position is described using latitude and longitude — a grid system covering the entire surface of the earth. You will hear positions constantly during operations: where a distress call originated, where a vessel was last spotted, where to search. Understanding what these numbers mean is essential.
How far north or south of the equator. Runs from 0° (equator) to 90° (poles). The Central Mediterranean SAR zone sits between roughly 30°N and 38°N. Higher number = further north.
How far east or west of the Prime Meridian (through Greenwich, London). Runs 0° to 180° East or West. The Central Mediterranean sits between roughly 10°E and 20°E.
Drag the sliders to move the position marker across the Central Mediterranean · © OpenStreetMap contributors, ODbL
When identifying the position of a target — a vessel in distress, a person in the water, another ship — relative to your vessel, SAR crews often use the clock system. The vessel's bow is always 12 o'clock. Everything else is described relative to that, as if the vessel is the centre of a clock face.
This is faster and less ambiguous than compass bearings for deck crew, and it works regardless of which direction the vessel is heading. Tap the clock positions below to see what each one means.
Nautical charts are the maps of the sea. Unlike road maps, they primarily show what is under the water — depth, hazards, shipping lanes, and coastal features — rather than what is above it. The bridge uses electronic chart systems (ECDIS) continuously, and paper charts are kept as backup.
You don't need to read a chart in detail, but understanding what you're looking at when you see one — during a briefing or on the bridge — helps you follow what's being discussed.
AIS is a tracking system that all vessels above a certain size are required to broadcast. It transmits the vessel's identity, position, course, speed, and destination. Aboard your vessel you will see AIS data displayed on chart plotters — showing all other AIS-equipped vessels in the area as symbols with their details.
Other vessels' names, positions, course, speed, and destination. Extremely useful for coordinating with nearby vessels during an operation — you can identify a passing merchant by name before calling them on VHF.
Small vessels, fishing boats, and overcrowded boats carrying migrants are typically not AIS-equipped. Persons in the water have no AIS signal. AIS is useful context — it is not a substitute for visual lookout.
MarineTraffic.com and its app show AIS data publicly. Useful for understanding what vessels are in your area before a deployment. Your own vessel will appear on it — SAR NGO vessels are often tracked by support teams onshore.
Radar detects objects regardless of whether they are transmitting AIS. The bridge uses radar continuously and it is particularly valuable at night and in poor visibility. Radar returns can reveal vessels and larger objects that have no AIS.
Five questions on position, the clock system, and situational awareness.