Friday Puzzler – Radar, Navigation and Rules of the Road
Ed Note – A very special thanks to everyone who commented on the Facebook posts at the JWorld Annapolis Facebook page during my recent delivery from Annapolis to Amelia Island, Florida. Randy Gray and Bill McGraw inspired the following post and puzzler, ripped from my notes from the trip. Everyone who posts a comment will be eligible for a free J World t-shirt. The drawing for the shirt will be Monday morning at 1100. Leaving a comment is easy. Just click comment at the bottom of the post and write away!
It was almost 0000 and the start of my fifth day out of Annapolis. The rhythm of sea life had set in and my body was getting used to the four hours on four hours off tempo that my delivery mate and I had set. I was aboard a 50′ catamaran that had sailed thousands of open ocean and Caribbean miles. We were headed to Amelia Island, Florida where the boat would hang for the winter, possibly making a jaunt or two over to the Bahamas and back.
Due in part to our December departure we had seen very little traffic. As I stepped onto the bridge deck to take my watch, the radar had two targets within four miles, both with intercepting course vectors and Bill was obviously hand steering – a rarity on this trip.
We were 30 miles east of the entrance to the river system that leads to Savannah, GA and as I zoomed out the screen the AIS showed that there were nearly a dozen fast moving freighters within 20 miles. A busy night at the helm and radar scope.
Shortly after Bill slipped off watch a freighter leaving via the Savannah Traffic Separation Scheme showed up on a crossing situation. It was an old friend. The freighter had passed us in the Chesapeake nearly five days before – the Atlantic Impala – confirmed by radar and AIS was still more than 16 miles out, but her course and speed had our Closest Point of Approach (CPA) within a mile of one another.
While the night was clear and the sea state relatively calm, I could not see the Atlantic Impala. But with radar I did start a record of the time, range, bearing and occasionally the CPA. Our courses were at nearly right angles to one another and neither of us seemed interested in slowing down or altering course – I was sure he wasn’t.
Here is what I wrote in my notebook during the crossing:
|0050||11.82||289||1.16/ Atlantic Impala|
|0056||9.9||290||38 mins to TCPA/attempted radio contact ch. 16/13|
|0109||6.3||293||Radio Contact attempted Ch. 16/13|
|0118||3.9||300||.961/ 14 mins to TCPA|
|0123||2.8||305||Port Light Vis.|
|0125||2.2||311||Both P & S Light Vis.|
So… what do you think? In an effort to save space I haven’t shared the entire situation (e.g. proximity of other vessels, shoals, etc.) Based upon the information available:
- According to the COLREGS who was the stand on vessel and who was the give way vessel? Why?
- What was I required to do according to the COLREGS? In the event that I was unsure or thought a collision was imminent, what was I required to do. What was the Atlantic Impala required to do in this situation?
- What sound signals would I have offered the Atlantic Impala if we had been within range of one another?
- What sound signals would the Atlantic Impala have made if she didn’t understand my intentions or didn’t think, based on her information, that I was crossing?
- Did I do the right thing by holding my course based on the radar information available to me?
- What were some of my available options and when would you have exercised the option?