ARPA option for old 1824C Furuno radar

ARPA stands for Automatic Radar Plotting Aid which is a means by which radar targets can be automatically (or manually if so desired) picked up for tracking with data displayed for the operator's use. Most boat radars I have been associated with do not have it, and in all likelihood don't need it.

That said, I became aware that my older Furuno radar and MFD (an RPD-149) combo had an option at purchase to add the ARPA option. A little online research quickly found that the necessary circuit board is no longer available from Furuno and that some eBay sellers were happy to part with them at prices which made the idea of upgrading just because I just wanted to, not because I NEEDED to, ridiculous. One board stood WAY out because of its affordability at about one ninth the others advertised, and I ordered it from the individual thinking I would not be out much if it failed - I did buy a Square D warranty. The original radar installation instructions aboard the boat give screw-by-screw (all 20 or so of them) steps to insert the board. I then found that the ARPA board will not function without what is called AD-10 data from the PG-500 fluxgate compass which strangely enough has an "AD-10" plug on it. The AD-10 cable part number was in the instructions, and R&D Marine had one for sale on good ol' eBay.

A quick pierside test this evening shows all ARPA functions working with the cable run directly to the MFD. Now come the hard part, threading it through the boat's interior between the compass down forward and the MFD up at the helm. Then a training run down the bay. This boat stuff is just a bunch of PHUN, ain't it?

I have that setup on my charter boat with an open array. Lots of fun to play with on night trips. It can be a little challenging to interpret what you're seeing when both you and the target are moving and then both are changing course.

One of the tricks you have to watch for is when your target passes another object. This is about radar reflections. Visualize your target going past a large seabouy with lots of radar reflective surface. The radar doesn't know which is the target and may jump to the seabuoy, telling you the target has stopped moving. It's a nice tool, but can easily be fooled.

Ted

I am probably about average age for around here, and I did get started in boating at a young age, but in the days before recreational radar (I was aware that 42'+ sportfishers had small refrigerator sized units on their flying bridges), not to mention GPS or even Loran, my navigation was based on dead reconing and RDF. One was never sure of one's location without a couple of reliable landmarks from which to triangulate, but I usually believed I knew where I was within a mile a two. And yet, knowing how "advanced" the then current technology was compared to prior centuries, I felt blessed.

Fast forward 45 years and the changes are remarkable. And, at least in terms of collision avoidance, two of the best are AIS and ARPA. Don't leave home without it.

With this Furuno setup of mine having only the one screen in a fast moving vessel, I need to be careful not to get absorbed with the toy, especially at night. There are many more options and controls on this older unit than I ever had on the simple Garmin radar I had on the trawler. My 7X50 binocs are still one of my best tools though. Knowing the local waters like the back of my hand helps a lot. Before it gets to be time to depend a bit more on the radar, I have to take some time to get it tuned and set up the way I need it to be. Slowing to a crawl is always an option for this part because my attention gets pulled from the looking out part - there is no room at my helm for another to conn while I fiddle with electronics. Once it is all set, "safe speed" gets defined upwards, and we're rolling home apace. If I were cruising and using more than about once a week like I am nowadays, I'd be far handier with all the options.