Gemini Encounter Back to Valhalla's Adventures
Returning to Pulau Langkawi, Malaysia from a short cruise among the islands, we were sailing in 18-22 knot NE winds on a starboard tack. I had the Yacht-AIS program running in the background on the computer while using the MaxSea program (my version does not support AIS) for navigation.
While among some islands the Yacht-AIS program detected a potential collision and sounded a warning signal. I brought up the Yacht-AIS program and saw the display shown at the bottom of this image. (Post-facto I have overlaid the displays for the purpose of this description). At the time (1006) our vessels were at the positions marked '0'. The unseen vessel was making 17.6 knots and we were sailing at 4.8 knots. We were not in sight of each other. I made contact with the 'SUPER STAR GEMINI' using their name and callsign as shown on the display. I was pleased to make contact and advised them that I was a sailing vessel on their starboard but not in sight due to the intervening islands. The reply was 'My intent is to proceed on my course to the jetty'. Not what I expected but at least they knew we were there and we would be wise to keep clear.
By 1013 we were in the following positions, still not in sight of each other.
At 1017 we got our first sight of the vessel at positions '2' ... a SUPERSTAR all right!!! Note that I had changed the Yacht-AIS display from 'north up' to 'course up'.
At 1021 we were in positions '3'.
At 1024 we were in positions '4'.
And finally, at 1031, positions '5', we had passed astern of the cruise ship, which had now slowed to 3.2 knots as it made it's approach to the jetty.
Benefits of this experience?? The AIS system alerted us to a danger of collision nine minutes before we saw the vessel. It allowed us to call the vessel by name and callsign while out of sight of each other and make our presence known. It eliminated what could have been a big surprise.