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6

Radar module 6 of 9

AIS, MARPA, and Overlays

Using AIS and MARPA alongside radar without over-trusting either.

AISMARPAchart overlaysensor limits

What to know for AIS, MARPA, and Overlays

Compare AIS, MARPA, and radar echoes and understand why disagreement must be investigated.

Using AIS and MARPA alongside radar without over-trusting either. This module is mapped to the published course boundary for Marine Radar Revision and written as an independent revision aid, not official training material.

Key Points

  • AIS depends on transmitted data
  • MARPA depends on radar quality and stable tracking
  • Chart overlay depends on heading, position, and chart accuracy
  • Radar can show targets that do not transmit AIS

Last reviewed: 6 July 2026 by Compass Revision curriculum review

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