Nautical navigation has a long history of innovation, from the compass and chronometer to today’s computer-driven autopilot systems. That said, the poor compatibility of electronics with saltwater has consequently created a need for rugged, waterproof computers, a category to which [Matti Airas] of Hat Labs has contributed with the open-source HALPI2.
Powered by the Raspberry Pi Compute Module 5, the electronics are housed in a heavy duty enclosure made of aluminium, which also serves as a heat sink, and closes with a waterproof seal. It has a wide variety of external connectors, all likewise waterproofed: power, HDMI, NMEA 2000 and NMEA 0183, Ethernet, two USB 3.0 ports, and an external WiFi or Bluetooth antenna. The external ports are plugged into the carrier board by short extension cables, and there are even more ports on the carrier board, including two HDMI connectors, two MIPI connectors, four USB ports, and a full GPIO header. The case has plugs to install additional PG7 or SP13 waterproof connectors, so if the existing external connectors aren’t enough, you can add your own.
Besides physical ruggedness, the design is also resistant to electrical damage. It can run on power in the 10-32 volt range, and is protected by a fuse. A supercapacitor bank preserves operation during a power glitch, and if the outage lasts for more than five seconds, can keep the system powered for 30-60 seconds while the operating system shuts down safely. The HALPI2 can also accept power over NMEA 2000, in which case it has the option to limit current draw to 0.9 amps.
The design was originally created to handle navigation, data logging, and other boating tasks, so it’s been configured for and tested with OpenPlotter. Its potential uses are broader than that, however, and it’s also been tested with Raspberry Pi OS for more general projects. Reading through its website, the most striking thing is how thoroughly this is documented: the site describes everything from the LED status indicators to the screws that close the housing – even a template for drilling mounting holes.
Given the quality of this project, it probably won’t surprise you to hear this isn’t [Matti]’s first piece of nautical electronics, having previously made Sailor HATs for the ESP32 and the Raspberry Pi.
So,
What happens to the Ethernet, USB and HDMI connections once their made up?
I spent a goodly parts of my professional life putting electronics in less than hospitable conditions.
These connects are going to have a very short life in a marine environment.
They are replaceable… The Pi stays safe inside, plugged to the box, and the box have a set of connectors plugged to the Pi and to itself.
So,
You’re 200 miles out at sea and your guidance device dies because water got into one or more of your connections.
Better hope you have spares and you are not in the middle of a life threatening weather situation.
Mother Nature is a cruel mistress.
BTDT.
Put some real waterproof connectors on this thing. Even they will fail, but not anywhere near a often as there’s open to the site connections.
$360 + shipping is too expensive for my taste but if it really solves the problem then I’m sure it’s worth it.
Aluminum is the bad choice for salt water use, plastic is a far better option.
Since you are in salt water you can use a heat exchange like what is used in IO And inboard vessel made for this purpose.
My last 2 cents have been spent!
It’s true that “Water corrodes — Salt water corrodes absolutely.” (Steven K. Roberts)
But the negative comments here seem overwrought. The designers look like they thought carefully about water ingress and corrosion.
For the belts-and-suspenders crowd for whom powder coating isn’t enough, there are a variety of nifty corrosion inhibitor products, e.g. https://www.hammfg.com/electrical/products/accessories/hvpci Hoffman is another supplier. Boeshield T-9 is a popular one too, but in my experience it is expensive (maybe because of its pedigree) and not effective.