A black, rectangular box is shown, with a number of waterproof screw connectors on the front.

A Ruggedized Raspberry Pi For Sailors

September 20, 2025 by Aaron Beckendorf 33 Comments

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.

A Survey Of Long-Term Waterproofing Options

March 27, 2023 by Matthew Carlson 27 Comments

When it comes to placing a project underwater, the easy way out is to just stick it in some sort of waterproof container, cover it with hot glue, and call it a day. But when you need to keep water out for several years, things get significantly harder. Luckily, [Patricia Beddows] and [Edward Mallon] from the Cave Pearl Project have written up their years of experience waterproofing data loggers for long-term deployment, making the process easier for the rest of us.

It starts with the actual board itself. Many SMD boards have at least some flux left over from the assembly process, which the duo notes has a tendency to pull water in under components. So the first step is to clean them thoroughly with an ultrasonic cleaner or toothbrush, though some parts such as RTCs, MEMs, or pressure sensors need to be handled with significant care.

Actual waterproofing starts with a coating like 422-B or nail polish which each have pros and cons. [Patricia] and [Edward] often apply coatings to PCBs even if they plan to otherwise seal it as it offers a final line of defense. The cut edges of PCBs need to be protected so that water can’t seep between layers, though care needs to be made for connectors like SD cards.

Encapsulation with a variety of materials such as hot glue, heat shrink tubing, superglue and baking soda, silicone rubber, liquid epoxy, paste epoxy (like J-B Weld), or even wax are all commented on. The biggest problem is that a material can be waterproof but not water vapor proof. This means that condensation can build up inside a housing. Temperature swings also can play havoc with sealings, causing gaps to appear as it expands or contracts.

Overall, it’s an incredible guide with helpful tips and tricks for anyone logging data underwater for science or even just trying to waterproof their favorite watch.

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He Comes To Bury Sensors, Not To Praise Them

June 12, 2019 by Al Williams 11 Comments

[Adosia] has some interesting videos about their IoT platform controlling self-watering plant pots. However, the video that really caught our eye was the experience in sealing up sensors that are going to be out in the field. Even if you aren’t using the exact sensors, the techniques are useful.

We would have expected to see potting compound, but that’s messy and hard to use so their process is simpler. First, a few coats of clear urethane sealant goes over the electronics. Next, heat shrink goes over the assembly. It isn’t ordinary heat shrink though, instead it’s the kind that has heat-activated adhesive inside.

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Exploring Options For DIY Waterproofing

December 26, 2017 by Dan Maloney 49 Comments

TL;DR — Don’t use silicone to pot electronics.

That’s the conclusion [GreatScott!] comes to after trying out several methods for waterproofing electronics. His efforts stem from a recent video in which he discovered that water and electricity sometimes actually do mix, as long as the water is distilled and the electronics in the drink are relatively simple. He found that the main problem was, unsurprisingly, electrolytic corrosion, so he set out to experiment with various waterproofing coatings. In a series of careful experiments he goes through the pros and cons of both conformal coatings and potting compounds. The conformal tests used simple clear nail polish on an ESC board; that worked pretty well, but it was a little hard to reach all the nooks and crannies. He also tried potting with a thick black silicone compound, but that ended up never really curing in the middle. A final attempt with legitimate two-part epoxy potting compound sealed up the ESC tight, although we doubt the resulting brick would perform well on a quadcopter.

If you want to explore potting a bit further, check out this introduction to the basics.

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