🔍 Key Concepts
• AIS antenna position dimensions (A, B, C, D) relative to the GPS antenna location
• Difference between vessel’s own dimensions and tow length when using AIS towing codes (like 57)
• Effect of the antenna being on the centerline and centered fore and aft
💭 Think About
• How are A, B, C, and D defined in the AIS standard? (Think: bow, stern, port, starboard distances from the GPS antenna, not from the tow.)
• Since the GPS antenna is exactly centered fore and aft and on the centerline, what does that tell you about the forward vs aft distances, and port vs starboard distances?
• Which answer choices are in feet and which are in meters, and which unit system matches the way AIS wants these values entered for your setup?
✅ Before You Answer
• Confirm that A + B equals the vessel’s length overall, not including the barge when using this AIS code for antenna position.
• Confirm that C + D equals the vessel’s breadth (beam) at the antenna’s location.
• Verify that your final choice uses the correct unit (feet vs meters) and matches the vessel’s given dimensions and centered antenna position.