Sunday, January 12, 2014
Broadcasting our presence
Posted by Sean
We are anchored in the Indian River lagoon, at the mouth of the Banana River near the community of Eau Gallie (map), a neighborhood of Melbourne, Florida. We are just north of the Eau Gallie causeway, and from here I can see the masts of boats in the Banana River, separated from us by a thin strip of land.
We arrived here early Thursday afternoon, after a very short cruise from Cocoa. With a full week before we can dock in Stuart we are in no hurry, and we spent a leisurely morning at the dock in Cocoa before shoving off around 11am. It was quite blustery and there was a bit of chop with winds out of the east, so we elected to make it a short day and anchor here in the lee of the islands to the east and the causeway to the south.
After we set the hook and got settled in, we decided we'd spend two nights here, so I could get some projects done. There is a small shopping center ashore with a Ross, Office Depot, Publix grocery, and a few other stores, and we figured we could dinghy in if we needed anything, although we have not splashed the tender since arriving.
Friday was a gorgeous day, with calm waters and lovely temperatures, and we had all our meals and cocktails on deck. We had breakfast and dinner on deck yesterday, too, although there was a windy bit in the middle of the day. Apparently Boston University trains their women's crew here, and we heard the coxswains and coaches shouting through bullhorns as they skulled by the past couple of days. Yesterday the sailboats were out in full force, along with a handful of jet-skis, and we've been treated to live music the past two nights emanating from Squid Lips bar and grill across the lagoon. It's all been very relaxing, other than the projects.
I intended to get cracking Friday morning on finishing up the bulk of the work on the new chartplotting system, and then start on the installation of the Furuno AIS transponder. But I ended up spending all morning Friday filling out the 5-page application for dockage in Stuart. It would have taken me perhaps twenty minutes to print it out, fill it out, scan it back in, and email it, but I really wanted to do the whole thing electronically, as we've done from the bus for the past nine years.
I had all the software to do this quite seamlessly on my Windows computer, no matter the format of the original. (That computer is now the new chartplotter, so, again, I could have simply gone over and done it from there, but I am stubborn.) My current machine is a Linux box, though, and while I lived and breathed Unix when I was at Bell Labs and Stanford a million years ago, I find myself at the bottom of the learning curve with respect to modern graphical tools for this platform.
I forced myself to hammer through it, and next time I need to fill out a form intended to first be printed it will take me just a few minutes, but there went the morning. (For the curious, I used Gimp and added my text and graphics in separate layers.) After lunch I emptied out the cabinets under the helm and settled in to my hidey-hole with a pair of dikes and a screwdriver.
After clearing cables back to the far reaches of the under-helm area, I sorted out where the new cables would have to run and then attacked the top surface of the cabinetry with a 2.5" hole saw. The old Northstar plotter ran on three fairly thin cables which only had connectors on the plotter end -- the other ends were loose and spliced or connected under the console, and the installer had run all three of them through a half-inch hole. Between the new chart system and the AIS I had a bundle of cables five or six times that size, and many were pre-connectorized. I have a nice finish grommet and cap for the new cutout, so it looks cleanly finished.
While the installation of the new plotter did not strictly require it, as long as I had to do all this work under the helm with power, signals, and cable routing, it made sense to tackle the heavy lifting on the AIS project at the same time. That necessitated a bunch of re-wiring of existing NMEA data paths, and there was a bit of trial-and-error, as the IMO-compliant Class-A transponder is very picky about input information. I spent hours trying to get the autopilot to supply heading information to the AIS unit, with no success.
Our autopilot takes its heading information from a magnetic compass, heavily compensated for the steel boat. Even though it is being supplied fix information from a GPS, and thus could calculate true heading based on deviation, it simply will not broadcast true heading if that's not what it is receiving as input. The AIS will not listen to magnetic heading sentences, only true heading.
After having run a full set of wires from the autopilot to the AIS for the heading information, in addition to the full set of wires from the Furuno radar/charplotter to the AIS to supply position, course, and speed information, what finally fixed the lack of heading at the AIS was to tell the Furuno plotter to send the true heading information. I think I would have tried that first were it not for the AIS documentation, which appeared to mandate that heading come in on a separate port dedicated to that purpose.
All's well that ends well, and even though I ran wires I didn't need and rewired the autopilot unnecessarily, I eventually got the AIS to stop screaming about missing inputs, and yesterday morning we came up on the air -- as the Washington State Ferry Walla Walla. I quickly powered down and rebooted into initial settup mode, and we now have the correct vessel particulars for Vector programmed in.
The AIS uses a lot of power, and it requires both the radar display and the autopilot to also be powered up so that it has a source of position, speed, and heading information. So now that testing is finished it is all powered back down, and will likely remain that way any time we are at anchor or moored. While there is arguably some safety benefit to showing up on other ships' AIS displays at anchor, particularly in areas with towboat traffic (a large ship can't really hit us because we anchor in water too shallow for them -- not so with tugs and barges), we're also a pretty visible radar target, and we really can't spare the juice.
The additional work on the chartplotter system involved moving the notebook computer to a cabinet under the helm and running cables from there to the monitor, the mouse, the power supply, etc. -- basically cleaning up and dressing the installation. Eventually the new AIS will also be connected to this computer, but I need some additional hardware, and I had to noodle through getting a new source of GPS information as well.
For the time being, the new plotter is still getting both GPS and AIS data from the old SeaCAS AIS unit mounted in the eyebrow above the pilothouse. This was handy for testing, because it means we can see ourselves -- the SeaCAS unit sees the transmission from the new Furuno unit as a target. and I had to filter it out on the alarm screen. It does mean that I had to rob the VHF antenna from the pilothouse radio to get the AIS working; once I remove the SeaCAS I can re purpose its VHF antenna for the Furuno. Getting the cable up to the eyebrow through our already over-stuffed cable chases will be a challenge, though.
I had been concerned about where the position information would come from for the new chartplotter once I remove the SeaCAS, which has its own GPS and broadcasts both AIS and GPS data on the same port. A little digging today revealed that the GPS "antenna" for the now-defunct Northstar plotter is actually a full, stand-alone SirfStar GPS NMEA "talker." It's already on the mast and the wires come in to a junction block under the helm. All I need to do is connect power to it and make a serial cable to connect it to the computer and I should get GPS position, speed, and course data.
The extra bit of hardware I need is a USB adapter that will give me more serial ports. The single-port unit I have now works fine with the SeaCAS, which sends GPS and AIS on the same cable. With the new setup, I need separate ports for each, and if I had an extra couple of ports I also can bring in heading from the autopilot and depth from the depthsounder. I'm sure the Office Depot here would have that item, but I ran out of day.
This morning we will weigh anchor, bound for Vero Beach. We have friends there, and they will pick us up at the city marina for dinner.