Boat Electronics Summary Report

Computers On Your Boat

A gorgeous mix of the old and the new
makes a fantastic navigation station
Boat electronics are expensive, and are just as poorly engineered as other consumer electronics. There is a collection of sensors all over the boat that are communicating with one central unit or interpreted by the sensors own display. Other systems such as the VHF radio, infotainment clusters, and security systems also sometimes hook into other units. Engines often do not have sensors installed that report conditions back in the same way a modern car does, and instead relies on aftermarket sensors. More likely than not you will find a switch panel that a navigator sits at and manually flips switches on, preforming the tasks of a computer manually.

Types of Sensors

The most commonly found sensors are the sonar transponders. They are little goobers mounted underneath the boat. They send sonar pulses that return to a control unit the depth under the sensor. On a fiberglass boat the transducer can be inside the boat and scanning through, but those are garbage for obvious reasons. The through-hull transducer is a better type. This is displayed on the central head or set off a simple alarm, sometimes by the radio or maybe just by a transucer system screen. There is a good chance you'll have a little green and black screen on a box from 1995 at the helm showing this, and almost all boats have one. If the box is gone, the 'ducers are still there. This system is also used to accurately report back the current speed of the boat with a dedicated 'speed transducer' mounted further up on the bow (in the water of course).
Ping? PONG!

Measuring fuel levels, engine temp and running hours, battery charge states, and other 'life support systems' all seem to be done either by black box digital devices with eye watering price tags or analog sensors connected to analog dials built into the bridge. Almost none of this is digitally monitored to trigger alarms or notifications. Usability considerations in the presentation of this information are nonexistent in most cases. Boats in our financial range are likely to NEVER have any such systems installed in a reliable and robust way, with boat fuel level sensors being one of the most commonly inoperable components. Any digital sensing of these systems will absolutely require retrofit or finding an existing salvageable system.
Measuring atmospheric and geo data is way more commonly in place in cheaper craft. Wind speed, temp, gps data, barometric data, compass, wind speed, and the like are often presented on the same screen as the sonar and radar data. 

VHF Radio Signalling

Lets talk about AIS for a second. AIS is a system in which all boats announce where they are, how fast they are going, who they are, and how long they are. This is broadcast in bursts over VHF radio, meaning you have to have a VHF radio to pick up and send out AIS announcements. Commercial boats, big boats, and cool boat people all HAVE to send out AIS messages (every 10 seconds to every 3 mins). This can be done with a computer plugged into a radio via mic jack and decoding the signals, or with a 20 dollar usb device, or with a dedicated device itself. Online there is a database of boats, and if you can get online you can get pics of the boats that are within radio range and their histories and contact info sometimes. Another cool thing is you can use AIS data to make a layer on your maps, with a dot where each boat near you is (this is literally miles), and you don't have to broadcast to read this data of course. There are a network of AIS receivers around the globe that are pumping the location data of vehicles in their range to the internet as well. Being able to track friends and family in real time on a virtual globe is almost trival to do as long as they maintain AIS signalling.
Craft broadcasting AIS signals colored by vehicle class

Chartplotter Options

The chartplotter is a mega expensive device that collects all this data but ALSO has the contour maps and weather prediction data coming in to actually do chart plotting. You tell it where you want to go and it analyzes the trip and plots it according to where the wind is supposed to be blowing at each step of the way. I cannot stress enough how important competent chartplotting is. The proprietary map data in these ecosystems are locked down like Fort Knox and map updates cost a lot. I've seen them with sat-phone internet uplinks, because the weather and USCG data update infrastructure is built in.
So when you look at pics of people with boats you'll find the helm covered in multiple screens. This is often a fish finder (sonar), gps with map, radar without map, weather info, and maybe something like an entertainment screen that also has the video feed from the mast; idk. OR you'll find 2-3 screens and one of them is a chartplotter.
There is one step further and that's to have an autopilot, which is what you would think it is. It costs as little as 500 bucks and up to the cost of a house, and takes all this data in and does things like 'go that direction' or 'keep the wind at this reference' while making adjustments to meet said goals. This is called 'self steering' and is mega complicado.

Communication Standards

The NMEA 2000 Standard Boat
So, you can either buy some separate things with their own little wireless screens or you can get things that integrate. How do they integrate? Well for the most part they integrate via NMEA2000 or NMEA0183. This is a standard compliant cabling, messaging, and power system that is NOT open source at all. If a device is NMEA compliant that means it can get power AND send/receive data to other devices through the data wiring in the craft. Yes, it transmits power too. The separate things route usually involves installing a wifi repeater on the boat so everything can get to everything else easily.

Maybe Open Source?

There are a few programs, I'm going with OpenCpn, that do the chartplotting biz AND collect data AND can communicate with devices. It CAN communicate with NMEA devices and run on any computer thing you can want. It's also open source so fuck the users and hail satan until you die. I can't wait to have to update a driver by morse code in order to make the motor run again or whatever nightmare would happen. Protip: all digital systems should have mechanical backups.
OpenCPN 4.0 Displaying AIS Data
Automation of sails is possible, maybe using the ROS robot control system I was picking around with for a while. There are other things floating around as well. This route also means we can cram low power arduino thingies everywhere to monitor things, or communicate with appropriate professional CANBus communicatin' sensors.
This is a real rough outline of what i've studied in the last 36ish hours but I have a pretty good grasp on a lot of it. I can identify what most gadgets do by sight and have trained myself to identify the different NMEA devices by plug; for salvage.
Yeah, I'm gonna put a computer on a boat.

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