Now that we're underway, let's quickly examine surface ship sensors. Note that it is currently night: Visual detection with the Mk1 Eyeball will be very poor so we will be relying on our surface search radar to detect the vessels we're looking for.

Radar: Radar is a staple of surface unit operations. When operating unopposed it is typical for ships to use at least a surface search or navigation radar. Radar is an active sensor and needs to be switched on to function (F9). Your patrol boat is equipped with a navigation radar (Decca 1226), a combination air and surface-search radar (TRS 3035 Triton II MTI) and two fire-control radars (TRS 3201 Castor II and TRS 3220 Pollux).

Radar performance is affected by several factors, but in this tutorial we are most concerned by radar horizon.

The maximum range of a radar is limited by the 'radar horizon', which is a factor of the curvature of the earth, the altitude of the target, the altitude of the receiver, atmospheric factors, and the frequency of the radio waves. An approximation of the radar horizon formula that is useful for surface ships is RNm = 1.23 sqrt(HRf + HTf) - the range in nautical miles (RNm) is equal to the product of 1.23 and the square root of the sum of the height of the receiver in feet (HRf) and height of the target in feet (HTf).

Thankfully, in most situations it is sufficient to know that the typical radar horizon for a surface ship detecting another surface ship is around 12 nautical miles.

There are a number of other factors that come into play, but for now we just need to be aware that the typical effective range for a ship-borne surface search radar is around 12 nautical miles, and that the range for any radar is limited by the radar horizon, which in turn is determined by the altitude of the target and receiver. Other tutorials in this series will delve deeper into the workings of radar.

Now, let's proceed south course and see if we can detect the vessels in distress using radar. Switch on your ship's radar by using the sensors window (F9) or the EMCON panel in the right-hand status panel. If using the sensors window (F9) you will need to ensure that the 'Unit obeys EMCON' box is unchecked, while if using the right-hand status panel you will need to ensure that 'Inherit from Parent' is unchecked. These settings are used in larger scenarios to manage the EMCON of multiple units simultaneously.