Your examiner asks: "Why does a radar use a short pulse on some range scales and a long pulse on others? What is gained and what is lost with each?"

A. Pulse length has no relationship to detection range. Maximum detection range depends solely on antenna height, regardless of pulse length.

B. Pulse length only affects the colour of the display. Short pulse is used at night and long pulse during the day; neither has any effect on range discrimination or minimum range.

C. A long pulse always gives better range discrimination than a short pulse, which is why long pulse is preferred for close-quarters pilotage in narrow channels.

D. A SHORT pulse contains less transmitted energy but gives better range discrimination (two targets close together on the same bearing can be distinguished as separate echoes) and a smaller minimum range (targets very close to own ship can still be detected) — it is used on short range scales for pilotage and close-quarters work. A LONG pulse contains more transmitted energy, giving greater maximum detection range and a stronger return from small or distant targets, but at the cost of worse range discrimination (two targets close together may merge into one elongated echo) and a larger minimum range. This is a fundamental trade-off — no single pulse length is best for all situations, which is why modern radars vary pulse length automatically or manually with range scale.

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

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

C. Testing should wait until cargo operations begin

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

A. Only the weather forecast for the next watch

B. The lunch schedule for the deck team

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

D. The cargo manifest for the next port