Latest News


Welcome to MV Tanglewood. Please fill out the "Follow this blog by email" (to the right) to receive notifications of updates to the blog. Thanks, and enjoy!

Monday, April 13, 2015

Declaring success on electronics 2.0

The electronics 2.0 refit is complete and we recently concluded a two week cruise that provided lots of opportunity to test everything out.  I'm now ready to declare success with the project.

Reconfigured helm for Electronics 2.0


Center piece in the refit are the two radar units, one primary and one secondary.  The problems with my previous Simrad radars were numerous, but top of the list was the radar target tracking function known as ARPA or MARPA that just didn't work worth a darn on the Simrad units.

ARPA on the Furuno radars is a whole other world, working just the way it's supposed to.  In the video below you can see a few key things.  It's not the greatest quality, but here's what you see:
  • The target ahead of us highlighted in red is a ferry crossing our path
  • The ferry has AIS as represented by a triangle over the target, with the ferry's course and speed represented by one of the dashed likes.
  • I have also locked onto the ferry with the radar's ARPA tracking feature.  That is represented by a circle around the target and a second course and heading line.
  • In stark contrast to the Simrad radar, the AIS and ARPA lines are the same (or very nearly the same) just as they should be.  On the Simrad radar the lines never agreed with each other, and the ARPA line wandered all over the place.  What you see on the Furuno radar is how it's supposed to work.
  • Back in this post I talked about Relative Motion vectors vs True Motion vectors, and how Relative Motion is the basis for collision avoidance in boats.  The commercial Furuno radars are all capable of displaying the course and speed lines as Relative Motion or True Motion.  In the video you can see where I switch back and forth between the two views.  The Relative Motion vector shows the ferry coming much closer to us, and depicts the projected position of the ferry relative to our boat over time.  The spot where the line comes closest to us is the Closest Point of Approach, or CPA, and we can see exactly how much separation we will have.  And with a little work we can also figure out the Time to Closest Point of Approach, or TCPA.  In both cases, the radar figures it all out for us and displays CPA and TCPA.  Most boaters are accustom to looking at CPA numbers, but what the numbers don't tell you is when/how you will pass the other boat.  Will they cross your bow, or will you cross their bow?  And do you really want to cross their bow, or would you rather adjust course and take their stern?  The Relative Motion line shows you exactly how we will pass, with the Ferry crossing our bow with about 1 mile CPA when it is at about our 2:00 position.

video

Next picture is a close up of another encounter showing the value of Relative Motion vectors, and the difference between that and a True Motion vector.  We are passing very close to this research vessel, and the radar is showing it's Relative Motion in the long dotted line.  You can see that they are passing to our stern about 1/8th of a mile away.  In contrast, you can see the smaller solid line coming directly out of the tip of the triangle.  For an AIS target that always shows the vessel's actual heading.  It's pretty clear now that we are just passing him, but if we were still further apart I think you can see how it's hard to tell (like you can't tell) how you are going to pass from the heading vector, and how much difference there can be between the Relative Motion and True Motion lines.

Relative vs True Motion vectors





And the next shot shows where it all pays off.  Here we are threading our way between two ferries crossing in opposing directions.  In the fog, this could be a hair raising experience, but not with the right tools and a good VHF.  I talked to both ferry captains as they were getting underway, and it was clear to all of us that we were going to clear each other with no trouble.  I never had to change course or speed.

Threading between crossing ferries
Now on to the secondary radar, a Furuno 1835 4kw dome radar.  This little guy is awesome.  It's not as feature rich as the big radar, and not as easy to use, but it works great and has all the key features that are missing from many recreational radars, like Relative Motion vectors.

In my Simrad setup my secondary radar was their 4G "broadband" radar which is supposed to be really good at close target detection.  In my experience, what that really means is that it sucks at distant target detection, and works much better on close targets.  But I think the 4kw dome that costs about the same and takes up about the same space and power, works better under all conditions.  We anchored for a day or two in a cove on Lopez Island and I fired up the radar to see how well it showed the cove and scattered crab trap and mooring buoys.

Judge for yourself, but in the picture below you can clearly see every buoy in the cove, clear as day.  The dashed circle, by the way, is a Variable Range Marker, or VRM.  When we anchored I set it so it was just touching the shore line.  By monitoring it I can get a quick indication of whether we have dragged anchor in any way, or if we have swung around and are getting too close to anything.

4kw dome radar shows every little buoy
Switching gears to the fish finder, the best thing to report is absolutely nothing.  It just works, exactly the way it's supposed to, no fuss, no muss.  That's the way I like.

And last is the autopilot, which is working well, but I'm going to hold you is suspense because I realize that I haven't finished the post describing the new pilot (actually pilots) along with the why and how.

After all this, I can't tell you how much of a relief it is to have all this working properly.  Not only do I no longer need to worry about it, but I can now turn attention to finishing up all the other projects that have been shoved to the back burner.  Over the past couple of weeks I've been able to pick off a number of them and it's GREAT to be making progress again....

Before I wrap this up, I'd like to reflect back on a couple of things to see where I screwed up so badly.  If you go back to December 2012, almost two and a half years ago, I posted the first blog entry on my thinking relative to the electronics.  The first two paragraphs say it all.  I think the biggest blunder is in the second paragraph when I said:

 ".. I think all the big vendors' radar systems are comparable.  Radar has been around a long time and is no big secret, so everyone has good products."

Wow was I wrong.  That was a colossally wrong assumption.  Having made that mistake, I ran right into the buzz saw that I described in the first paragraph, namely vendor lock-in around chart plotters, and how it's an all-or-nothing proposition.  For Simrad, it started out as "all", and ended up as "nothing".

And this was a foreboding paragraph:

"I'm also nervous about Simrad's support.  I bought a WR20 remote for my current boat and it was flakey from the get-go.  Support was OK, but very slow with a return for repair that took almost a month.  An in-warranty repair should be advance-replacement, and in fact I later read that Simrad advertises just that, but it wasn't offered to me when I had a repair need.  My other support incidents have been less than thrilling.  Not bad, but not confidence inspiring either."

And last but not least, there is What Makes and Experiment and Experiment?  This was definitely an experiment.

So there you have it.  Now we know the outcome of the experiments.  Some succeeded, and some failed.  And in the end I learned a ton and have a boat that's better equipped than if I had never done the experiment in the first place.  So no regrets.