Boys and their toys...

I am a geek. I love technology and especially when bits-o-tech talk to other bits-o-tech.
But I am also a cheap bastard. I don't like spending money on things that don't directly benefit my life... So as part of the spring refit, I am installing some new instruments on the boat.

The "normal" instrument package for a boat in my size range is the Raymarine ST60+ package that includes depth, speed and wind sensors as well as their respective displays. Each display is a roughly 4"x4" square bezel that mounts in the bulkhead of my cockpit. These displays are essentially waterproof, backlit, large character, 3-digit, seven segment LCD displays capable of showing water depth, speed of water under the hull and wind speed/direction. Meh.

What I did last season for my first season out was to use an old laptop and LCD screen on a flexible arm that could be seen from the cockpit. The laptop ran GPSNavX, a chartplotting package for the Mac. Charts were in BSB4 format, provided by the Canadian Hydrographic Service. And the GPS was a small USB/bluetooth GPS data logger. this worked great but was frankly a bit fidgety and rather power hungry. See a previous post about a dead battery preventing me from pulling my mast for the winter. I also used the existing instruments (depth/speed) to compare with the depths marked on the charts. These instruments have bright orange incandescent bulbs for each segment of the 7-segment display of each digit. The instrument cluster has a control box down below for setting depth alarms, brightness, etc. It's all very 70s and very retro and very much not my style.

My new instruments are as follows:
- Airmar DST800 combination depth/speed/temperature sensor (Furuno 235DST-MSE)
- Technologic Systems TS-TPC-7390 touch panel computer.
- generic usb/bluetooth GPS
- next season, I will get the Airmar PB150 weather station.

The DST800 gives me speed temperature and depth in one unit, meaning one hole in the boat. The old instruments each required their own sensor and subsequent hole. Also, the new transducer is a "smart sensor" which means it outputs its data in NMEA-0183 format. This is a basic serial line protocol that runs at 4800 baud, 8-N-1. I can connect the two data wires directly to an RS232 header on the TS-TPC-7390...

The TS-TPC-7390 is the heart of my instruments. It is a 7" touch panel computer with a 200MHz ARM9 cpu and 128MB of RAM. It runs an embedded Debian OS off of 512MB internal flash and an SD card slot. It boots to a shell in under 2 seconds and a usable X Windows desktop in 17 seconds. It has an aluminum bezel and gaskets to make it splash-proof, although it lacks IP67 or NEMA4 certification. But at $509, it's also 25% the cost of so-certified devices... Now, it doesn't have any navigation instrumentation software out of the box so I have some development work ahead of me. But here is where the magic of open software shines. I am building on top of gpsd and nmead and will be using perl/Tk or wxPython for the user interface. My goal for this season is to just have a 4-way split window showing water depth, speed through water, speed over ground (from GPS), and direction (from GPS). Ultimately, I plan to build a gui that will let me select the screen layout and what information to display in each panel.

The advantage of using these new instruments is that should I decide that the touch panel computer just doesn't cut it in the real world, I only have to add in some Raymarine or Furuno or whoever display units and the DST800 transducer as well as the PB150 weather station will work just fine with them.

Chartplotting will continue to be done on my laptop for now, but instead of an old iBook laptop and external monitor, I am using an Acer Aspire One netbook with SeaFarer/LX which is chartplotting software for Linux. This will have to connect to its NMEA data source from the touch panel. Also, at present SeaFarer does not support BSB4 charts which are encrypted. So I will have to scan the paper charts for my area into tiff format and geo-reference them. However, the developer of SeaFarer did mention that he has BSB4 working and it will soon be ready for beta testing. He has also produced a software package in the past for the Sharp Zaurus called zNav which does very basic chartplotting functions on that ARM-based mobile platform. Perhaps it could be revived and I could run the chartplotting directly on my touch panel. Endless possibilities, but extremely finite time.

Stay tuned...