ARPA - Automatic Radar Plotting Aid
Eating crow (archaically, eating boiled crow) is an English idiom meaning humiliation by admitting wrongness or having been proven wrong after taking a strong position.
So, those of you who have been reading this log for a while, may remember me poo-pooing the ARPA class - before I had taken it. Part of this came from what I felt was a fairly underwhelming electronic navigation course. For some sailors, the computer technology is pretty arcane, and I understand the need to bring them up to speed, but I felt we could have spent 2 days on it, and we really didn’t fill 5 days. Plus, the state of electronic navigation is in major flux right now, so much of the information was tentative or irrelevant. All in all, it was an ok course, but should have been an elective - it’s not required by the Coasties.
However, I am prepared to eat crow on ARPA. It was a great course. In fact, one of the best courses I have had at PMI. Ok, the first day was annoying - because it was a one day radar renewal course - which I had just taken in the spring — but it was a good refresher. The next four days where intense. Each day I learned a little tidbit of information that helped understand some of the nuances of ARPA and cleared some misunderstandings.
I knew about steady state tracking, and that the inputs had to be good to get good data but I learned some other important nuances: trial functions, how CPA/TCPA alarms really work, and how to get false Ground Stabilization (which I believe is really common).
But the real power of the class was in the blind bridge simulators.
Part of the class grade is a practical assessment - and each day we practiced the assessment for an hour or two. The object was to cross Cooke’s Pass with heavy traffic - with a two mile CPA(Closest Point of Approach) — that means you have to keep the other vessel two miles away from you. If you called the contact on the radio you were allowed a 1 mile CPA - however it was in the blind bridges - so no visual contact. AIS was not used so we had to identify each contact via radio and figure out who was who.
Some of the practice runs were made more difficult when a team got into trouble, because their decisions had a ripple effect on everyone.
I got lucky and partnered with an apprentice pilot - so I learned as much from him as from the class itself. Gather information - only use the radio when you need to - but do use it - extend the vectors and find out who is going to be your next concern and contact them when there is a need to make arrangements.
