When a vessel or person is reported in distress, the rescue team must find them before the rescue can begin. In the open ocean this is not trivial — a overcrowded boat is a small object in a large sea, and wind and current move it continuously from the last known position.
Search patterns are systematic methods for covering a defined area. Understanding them helps you follow the vessel's movements during a search phase, understand why the bridge is manoeuvring the way it is, and contribute effectively as a deck lookout.
A vessel or person in the water does not stay where they were last reported. Wind and current move them continuously. Search planning must account for this movement — calculating where the target is likely to be now, not where it was when the alert was received.
Surface currents move everything in the water — vessels, dinghies, and people. Current strength and direction are factored into search planning. In the Central Mediterranean, currents vary by season and location — the bridge uses oceanographic data to estimate drift.
Wind acting on the above-water part of a vessel or object pushes it downwind. A heavily loaded overcrowded boat has significant leeway — it can move several miles per hour in strong winds. Leeway is one of the most significant factors in search planning.
The datum is the most probable position of the search object at the time of the search — calculated by applying drift and leeway to the last known position over the elapsed time. The search area is defined around the datum, accounting for uncertainty in position and drift estimates. This calculation is performed by the bridge, SARCO, or MRCC using IAMSAR methods or dedicated software.
The IAMSAR Manual provides the framework for calculating search areas and selecting patterns. Many vessels and MRCCs also use SARCalc — software that calculates drift, leeway, datum, and optimal search patterns. The bridge and SARCO use these tools; you don't need to operate them, but you may see them in use during briefings.
Different situations call for different search patterns. The choice depends on the size and shape of the search area, the number of assets available, weather conditions, and the nature of the target. In practice, humanitarian SAR operations most often use the expanding square (when the datum is confirmed) or the parallel track (when the area is large or the datum is uncertain). The others below are useful to understand but less frequently used.
During a search phase, deck crew serve as the vessel's eyes. The bridge has radar and AIS, but a overcrowded boat or person in the water may not appear on either. Visual lookout from deck positions is often the most effective detection method, particularly in calm conditions.
In humanitarian SAR, lookouts typically cover the full 360° around the vessel — not just a forward arc. Different organisations work this differently; some allocate sectors, some have lookouts moving around the deck. Either way, the goal is no gaps. Be conscious of blind spots created by deck structures, the bridge, lifeboats, the funnel — work around them so nothing is missed.
Do not stare at one spot — scan slowly across the area in overlapping arcs. The eye detects movement and contrast better with slow scanning than fixed staring. Work from the horizon in toward the vessel, then back out.
An overcrowded boat is low, dark, and partially submerged. In a swell it will disappear from view for seconds at a time. Look for colour contrast (orange, blue, yellow distress signals), smoke, lights, people waving, and any object that seems out of place in the sea surface.
If you see anything — even something you're not sure about — report it immediately using the clock position and distance. Do not wait to confirm. A false alarm costs minutes. Missing a target can cost lives. Always err toward reporting.
Voices, whistles, engine noise, splashes — sound carries across water and can locate a target before sight does, especially in low visibility or at night. Lookout is a focused task. No music, no headphones, no phone scrolling. Your senses are the equipment.
Sun glare on the water — particularly in the early morning or late afternoon — creates significant blind spots. Binoculars and polarised sunglasses help. Position yourself to avoid looking directly into the sun where possible, and stay alert to changing visibility through your shift.
MRCC briefings tell you the situation. Your vessel proposes a search pattern. Work through three realistic briefings and select the pattern best suited to each.
Five questions on search patterns and lookout.