Wednesday, August 29, 2007

Preparing for the Journey - Nav Station Update

Last year, we carried a laptop (actually, a Motion Computing Tablet PC) along with us as a chart plotter. Although most navigation around here can be done by coastal pilotage, there are occasions where a plotter is a nice plus (not to mention, it's fun to have a record of where you've been).

I've been looking at the various options for quite some time. There are quite a few options out there, many of which are terribly expensive. While I would love to have a multi-station Raymarine system with all the bells and whistles, I needed something that would better fit the budget (at least at this point). The solution came in the form of a PC.

The original nav station for Frog Prints was very basic - electrical panels, ICom VHF, Furuno GPS32, and basic electrical and tank gauges. Over a year or so, much of this will be changing.

The new chart plotter is a small form factor PC connected to a 15" LCD touchscreen mounted at the nav table. I'd been comparison shopping for quite some time before settling on this specific kit. It's not perfect, but it fit the budget.

The PC itself is a low-end Via Mini-ITX system mounted in a VoomPC case intended for use in cars. All the components were purchased from Logic Supply. The Via PCs are clone processors - in this case a 1.2 GHz EN-series board with 1GB of RAM mounted. The Via designs give a full-featured PC that fits in a case about the size of a shoebox that can run navigation software pretty well on about 24 watts. I don't know if there are more capable solutions with similar power consumption available, but this one works pretty well. The PC is now mounted in the little space under the nav table - the one about knee height.

The LCD is a 15" ELO Touchsystems monitor I picked up used on eBay for about $120 - they come cheap if you have the patience to wait for one. I was hoping to pick up a panel-mount model to make my life easy, but they just weren't showing up so I settled for a regular desktop one. I figured I could take the case apart and convert it into a panel mount. It worked pretty well, but it turned out to be trickier woodworking than I expected - the seam between the front and back parts of the display are a much more irregular design than I was expecting. The touchscreen draws about 12 watts - mainly for the back light.

Power on a boat is another tricky thing - everything is really only nominally 12V. For the PC itself, this wasn't so much of a problem. They make power supplies meant for use in cars which can handle a wide range of input voltages (usually from around 8V to 18V), and even can automatically shut down the system if its switched power is turned off, or if the voltage drops below a set level.

The monitor was a bit trickier. The ELO panel internally uses +5 and +15V for the logic and back light respectively. Because I wanted to have a very efficient solution, this meant I had to dust off my old EE skills and gin something up.

Because the ELO monitors normally take AC in directly to the case (no power brick necessary), that provided a nice chunk of space inside the case to work with. I took out the original AC supply and built a new board with a couple TI switching regulators that fit in the same place. The TI regulators are supposed to be over 85% efficient, and seem to meet that goal. They don't generate much heat, and didn't require much in the way of additional components.

Along with the monitor, it's panel at the nav station also include a thing called an X-Key Stick from PI Engineering. This is basically a stick of 14 back lit buttons that can be programmed to do just about anything. They're great for providing easy access to any functions of the chart software that aren't easy to use with the touchscreen.

Speaking of software, we decided last year to opt for Chart Navigator Professional (the Maptech name), which is also Coastal Explorer from Rosepoint Navigation. CNP is wonderfully easy to use, has a mode that works really well with touch screens, and is very affordable. We picked it up on special at West Marine last year for $399 including a full set of vector, raster, photo, and topo maps for the entire US. We added the CHS maps for the east side of Vancouver Island this year (raster only - the vector maps are $499) so it now covers our entire current cruising range. I can't recommend this package enough.

The PC also includes iTunes with our entire CD collection, and electronic versions of all kinds of documentation - everything from the Coast Pilot to all the manuals for on-board equipment. It's running Windows XP (I wouldn't recommend Vista for these types of low-power applications yet). I set everything up so that it could eventually have the OS and programs on flash memory, but I haven't managed to shoehorn the flash drive into the case yet.

It's also set up to use the Windows Shared Computer Toolkit, which has now been replaced by something called Windows Steady State. This is a set of tools to lock down a PC. and also sets it up to undo any changes that are made. This means that charters can screw with the PC and it will return right back to its original configuration when rebooted. I don't have this all working yet, but it's getting there.

There are two power switches on the panel - one switches both the PC and the monitor, while the other switches just the monitor. That allows saving about an amp (the monitor power) without shutting down the PC. The power wiring for the PC is set up for a future installation of a 12V UPS which will allow the PC to shut down gracefully if the power is switched off. I've been meaning to install such a thing anyway to maintain the memory in the stereo - right now it loses all its presets when the Comfort circuit breaker is shut off. There's also a USB hub mounted under the LCD panel for easy connection of a keyboard, mouse, or other accessories.

Since installing the touch screen required rearranging a bunch of stuff on the two nav station panels, I decided to just replace the panels rather than hacking up the originals (I didn't want to mangle the nice original wood). The new panels are 1/2" marine plywood with a mahogany veneer applied to make it look a little more like the original wood. The Moabi veneer Dufour uses is much nicer, but I haven't found a source yet. I had Daly's Paints in Bellevue color-match the stain to the original woodwork. The color they came up with isn't exact, but it works pretty well on both the Mahogany veneer and on oak (used for a knife holder in the galley).

In shuffling around the panels, I also added a Xantrex battery monitor (the XBM - Jackrabbit has a nice installation package) and left a space for a Raymarine repeater for instruments and future autopilot. The battery monitor won't be hooked up until this winter, since I need to redo a bunch of the wiring at the batteries to accomodate the shunt. I also intend to replace some of the analog guages with CruzPro equivalents, like their smart tank guages for fuel and water. I like the look of the analog guages, but I've had problems with the accuracy of the water guages. Finally, I added a string to support the panel when its down to protect the VHF (the thickest thing on the panel).

Overall, everything is working pretty well. The GPS feeds both the VHF and the PC, and it all looks pretty nice. There are a couple small goofs that probably only I will ever notice, but I'll probably fix them at some point - I really like to keep the boat in a factory-like condition. There is some RF interference on the FM radio to deal with, and the USB devices go flaky every once in a while, but I think I can tackle those problems. I'd also like to add an AIS receiver (you'll see why in my posts from the trip) and a low-power GPS logger for when the PC is off. I also need to wire the PC into the stereo. There's always something.

None of the PC components have been marineized. I figure most was inexpensive enough I'll give it a shot in stock condition first. If I run into problems, I'll at least add conformal coatings to all the electronics in any replacements. Everything is pretty safe from salt water, but I do worry about condensation.

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