For those who like to muck around in boats, there’s enough to worry about without wondering if you’re going to run aground. And there’s really no way to know that other than to work from charts that show you exactly what lies beneath. But what does one do for places where no such charts exist? Easy — make your own homebrew water depth logger.
Thankfully, gone are the days when an able seaman would manually deploy the sounding line and call out the depth to the bottom. [Neumi]’s sounding rig uses an off-the-shelf sonar depth sounder, one with NMEA, or National Marine Electronic Association, output. Combined with a GPS module and an Arduino with an SD card, the rig can keep track not only of how much water is below it, but exactly where the measurement point is. The whole thing is rigged up to an inflatable dinghy which lets it slowly ply the confines of a small marina, working in and out of the nooks and crannies. A bit of Python and matplotlib stitches that data together into a bathymetric map of the harbor, with pretty fine detail. The chart also takes the tides into account, as the water level varies quite a bit over the four hours it takes to gather all the data. See it in action in the video after the hop.
There’s something cool about revealing the mysteries of the deep, even if they’re not that deep. Want to go a little deeper? We’ve seen that before too.
We’re not sure how many of you out there own a boat large enough to get its own integrated computer network, but it doesn’t really matter. Even if you can’t use this project personally, it’s impossible not to be impressed with the work [mgrouch] has put into the “Bareboat Necessities” project. From the construction of the hardware to the phenomenal documentation, there’s plenty that even landlubbers can learn from this project.
In its fully realized form, the onboard computer system includes several components that work together to provide a wealth of valuable information to the operator.
What [mgrouch] calls the “Boat Computer” contains a Raspberry Pi 4, a dAISy AIS receiver, an RTL-SDR, a GPS receiver, serial adapters, and the myriad of wires required to get them all talking to each other inside a weatherproof enclosure. As you might expect, this involves running all the connections through watertight panel mounts.
Combined with a suite of open source software tools, the “Boat Computer” is capable of interfacing with NMEA sensors and hardware, receive weather information directly from NOAA satellites, track ships, and of course plot your current position on a digital chart. The computer itself is designed to stay safely below deck, while the operator interacts with it through an Argonaut M7 waterproofed HDMI touch screen located in the cockpit.
For some people, that might be enough. But for those who want to do big, [mgrouch] further details the “Boat Gateway” device. This unit contains an LTE-equipped WiFi router running OpenWrt and all the external antennas required to turn the boat into a floating hotspot. Of course it also has RJ45 jacks to connect up to the other components of the onboard system, and it even includes an M5Stack Core with LAN module so it can display a select subset of sensor readings and navigational data.
Admit it: when you first heard of the concept of the Unix Epoch, you sat down with a calculator to see when exactly 2³¹-1 seconds would be from midnight UTC on January 1, 1970. Personally, I did that math right around the time my company hired contractors to put “Y2K Suspect” stickers on every piece of equipment that looked like it might have a computer in it, so the fact that the big day would come sometime in 2038 was both comforting and terrifying.
[Forklift] is similarly entranced by the idea of the Unix Epoch and built a clock to display it, at least for the next 20 years or so. Accommodating the eventual maximum value of 2,147,483,647, plus the more practical ISO-8601 format, required a few more digits than the usual clock – sixteen to be exact. The blue seven-segment displays make an impression in the sleek wooden case, about which there is sadly no detail in the build log. But the internals are well documented, and include a GPS module and an RTC. The clock parses the NMEA time string from the satellites and syncs the RTC. There’s a brief video below of the clock in action.
We really like the look of [Forklift]’s clock, and watching the seconds count up to the eventual overflow seems like a fun way to spend the next two decades. It’s not the first Epoch clock we’ve featured, of course, but it’s pretty slick.
First off, check out that miniscule GPS antenna module, crazy! But we digress. For testing purposes the asynchronous UART of the GPS was probed, proving that the data can be acquired. From there [j3tstream] moved to an Arduino Pro Mini with an SD card for data logging. The uC is powered from the GPS board but this will quickly exhaust the stock battery so [j3tstream] swapped it out for one from an old cellphone.
That little dot-matix LCD that comes with the unit also caught our eye. If you can hack a headless interface for the GPS that could be repurposed for your next project. May we suggest a wearable gaming project for it?
[Mike Holden] has been on the hunt for a display that is easy to read in bright sunlight. He wants to use it to read out navigational data on his sail boat. The best option is an ePaper display. He managed to build a system that will feed updating NMEA 0183 data to a Nook Simple Touch.
NMEA 0183 is a protocol that governs data from marine navigational equipment. The most obvious is GPS, but there are a lot of possibilities like sonar, a gyrocompass, and an autopilot. To get things rolling he wrote an Arduino sketch which generates dummy packets using the standard. This let him develop and test the system without being near any of the real equipment. The heart of the build is a WiFi router. It pulls in the data over a USB port using an RS232 to USB converter cable. A Python script parses the data and generates a webpage which refreshes the data every second. This is loaded using Opera browser on the Nook
Check out the video after the break to see a demo of the system.