BRIDGE RADAR

Question 1

RADAR is required by ships?

Answer 1

9 GHz Radar – is required on any vessel of 300 GT and over.
3 GHz Radar – to be fitted as the second radar, which is required on ships of 3000 GT and over unless the Administration considers it appropriate to carry a second 9 GHz Radar.

Question 2

Limitations of RADAR?

Answer 2

What are the limitations or RADAR?

• Target information dependent own vessel course and speed.
• Small vessels, ice or objects may not be detected.
• RADAR echoes may be obscured by sea or rain clutter.
• Blind sectors from their own vessel structure.
• Shadow sectors from external.
• Multipath Echoes - Strong echo received by a ship at close range - Reduce Gain.
• Indirect echoes - reflection of a true target off another surface Same range, different bearing - Check visually
• Side lobe error - Weaker beam adjacent from the main beam produces echo - Reduce Gain.
• Interference Echoes - 2 radars on same frequency can produce spiralling pattern - Press interference suppression.
• Sub refraction, when there is cold air over a warm sea, the beam refracts up, range decreases by 20%
• Super refraction, warm air over a cold sea, beam refracts down, range increases by 40%
• Ducting, a band of warm stagnant air, the beam travels very long distances, land from very far away appears much closer, this is very rare