Your examiner asks: "In simple terms, explain how a marine radar determines the range and bearing of a target."

A. The radar transmits a short pulse of RF energy from a rotating scanner. Part of the energy striking a target is reflected back as an echo. RANGE is found from the time taken for the pulse to travel to the target and back: since the pulse travels at the speed of light (c), range = (c × t) / 2, where t is the elapsed time — the division by 2 accounts for the two-way journey. BEARING is found from the direction the scanner (and therefore the narrow transmitted beam) was pointing at the instant the echo was received, referenced to the heading marker (relative bearing) or to north if gyro-stabilised (true bearing). The scanner rotates continuously so that range and bearing are refreshed on every sweep.

B. The radar transmits continuously in all directions simultaneously. Range is found from the strength (amplitude) of the returning signal, and bearing is calculated by triangulation between three fixed antennas.

C. Range is measured directly from the target's AIS transponder reply, and the radar scanner only provides the bearing. Without AIS fitted, a radar cannot determine range to a target.

D. The radar measures the Doppler shift of the returning echo to calculate range, and bearing is fixed by the ship's gyrocompass heading rather than the scanner's rotation.

A. Nothing — a test lift can proceed immediately after repairs

B. Testing should wait until cargo operations begin

C. The area within the grab's swing radius should be cleared of personnel before the lift

D. Only the crane operator needs to be aware the lift is happening

A. Who must remain clear of the exclusion zone while the lift takes place

B. The lunch schedule for the deck team

C. Only the weather forecast for the next watch

D. The cargo manifest for the next port