As explained in our previous post, we have been working on improving the balance between electrical production and consumption over the last 4 years. While at it, we had to adapt, reorganize, rewire quite a bit of the electronic devices on board.
Agile to the rescue
When reducing our electrical needs, the first step has been to progressively decommission the aging devices with a large screen: the old chart plotter and the semi-functional AIS. A modern GPS (SIMRAD GP25) was fitted and a powerful AIS + NMEA to WiFi Gateway (Vesper Marine XB-8000) came on board.
At that point, we knew that the electronic stack on board was about to become complex – not for the thrill of it, but because we always thought that with good input data (AIS data, Grib weather files from the internet, a nice way of displaying and sharing all this data, etc.), you can make informed – and hopefully better – decisions.
Taking the right decision can make the difference between an enjoyable trip and a dangerous ride.
While more capable electronics are useful, complexity is not your friend at sea. When sailing, you need systems that just work… or that can fail gracefully, at least. In order to deal with this growing complexity, we decided to cut it into manageable chunks with some 功夫 (Agile-Fu). Each chunk of the system provides a single service; each service should be independent from the others and should provide a bit of redundancy.
This was an ambitious work, but by dealing with small manageable chunks, we did it! Of course, the results of this work are probably not much different from the results one could have obtained otherwise (using a different approach). As usual, the journey is more important that the destination: in our case, the agile methodology insured that every chunk had a well defined purpose. And by setting a minimum viable set of functionality for each chunk, we knew exactly when the chunk was good enough for us and could be considered as “done“.
By doing so, we were also able to work on the electronic stack by iterations: we got it all done over the last 4 years, and every summer we had working electronics on board.
Sorting devices by purpose
To give a concrete view of the results, here is how the groups of devices are organised on board Soledad, in 2017. Each “manageable chunk” became a group of devices:
- Instruments: NMEA2000 backbone (wind, depth/speed/temp, GPS, gyro-compass, rudder feedback)
- Autopilot: autopilot calculator and actuator
- Radio: VHF Antenna splitter
- AIS / Gateway: AIS / NMEA2000 to wifi gateway
- Navigation: portable devices
- VHF: VHF radio
- VHF subgroup: Bluetooth VHF handset
- FM radio: FM/stereo
- AIS / Gateway: AIS / NMEA2000 to wifi gateway
- Navigation: navigation computer
- Screen: navigation computer’s screen
- Ethernet/WiFi intranet: WiFi/ethernet router
- Internet: Internet 4G access
- Network storage: NAS
Each group is autonomous and only depends on its “parent” group in the hierarchy. Some groups can provide better functionality when other groups are up and running.
e.g. For the autopilot to work, the basic navigation package needs to be “on”.
e.g. The VHF Bluetooth handset needs the VHF to be “on”, which in turn needs the VHF antenna splitter to be “on”.
Splitting devices into logical groups helps to separate the different services, and makes sure that each group is viable in a standalone mode. It also helps to ensure redundancy for critical services.
e.g. AIS service and “instruments” service are on 2 separate groups: both groups have their own GPS (all Class B AIS transponders have their own GPS). The DSC VHF (which needs a GPS position for DSC emergency calls) is physically linked to both groups and has access to GPS data from any of the groups.
It has been extremely useful in the electrical consumption reduction process. Now, the basic “navigation” mode includes only the following:
- The basic navigation package (with autopilot, optionally)
- The radio group (antenna splitter) with the VHF radio
This means, no chart plotter, no monitor/screen… but a fully working autopilot in all modes (wind, no drift, fixed course), with minimal electrical needs.
The basic “watching-a-film-while-anchored” configuration includes:
- The ethernet/wifi intranet group with the NAS up and runnig
- The navigation computer with its screen
Here is diagram of the current networks on board Soledad. All it took was a bit (to say the least) of planning, head scratching and finding information (mostly technical specifications) for some of the devices ; the rest was “just” moving cables around and making new connections.
For the rest of this post, here are a few sections about electronics and working on electronics on board, in a “brain dump” format.
Using standard electronic devices on a boat
Selecting good candidates
As you might have guessed from the above diagram, several devices in use on board originate from the mass market (i.e. they are not “marine” devices), namely:
- Our D-Link DWR-921 4G router
- The Minix Z64A SoC computer (used for navigation)
- The Synology DS116 NAS
- The Philips 22″ monitor (227E6LDSD/00)
Of course, the main reason behind this is the big savings compared to “marine” specific devices. It is also nice to work with devices that are not using obscure protocols, wire/plugs formats… but selecting which devices are acceptable is a tedious process. Here are the criterion we use when hunting:
- Make sure the devices runs on 12V (or 5V – like all USB devices)
- Prefer sealed devices (or at least without fans)
- Make sure their power needs are low (keep an eye on devices designed for cars: they usually have a poor efficiency)
- Make sure to use a voltage stabilizer to feed them with clean 12V
- Install those devices in dry/protected places
- Fill all empty ports (USB, ethernet, VGA, etc.) with silicon plugs
Wiring and connecting devices
To wire any devices on board, it is very important to make good connections: use heat-shrink wrapping and soldering, use large section cables (2 x 2.5 mm² – which corresponds to 14 AWG, if you are from over there), prefer cables with “tinned” conductors, prefer rubber external jacket over a PVC jacket (rubber is resistant to oil, petrol and abrasion), use waterproof boxes to protect your Wago® connectors.
Every time we did not follow those rules, we ended up regretting it.
FYI, the European harmonized code for such cables is:
H07RN-F 2 x 2.5 mm² || || | | |_ 2.5 mm² per conductor || || | |_____ 2 conductors || || |_______ Finely stranded (i.e. flexible) || ||_________ Neoprene conductor jacket || |__________ Rubber outer jacket (oil, petrol, abrasion...) ||____________ 450V to 750V rating (that should be enough :-) |_____________ H for "Harmonized" standard notation
Protecting devices from electrical surges
For 12V devices, we like to use a voltage stabilizer. If you think about the voltage changes when the engine’s alternator kicks in or when the main sail comes and goes over the solar panels, you understand the need to protect those fragile devices from the surges. Those voltage stabilizers (usually) consume very little and can save your electronics.
To feed 5V devices from 12V, we use a UBEC – a DC Step-down, designed to deliver clean 5V voltage from anything between 6 to 24 V, in harsh environments (e.g. radio-controlled drones and cars), with a very high efficiency and top reliability. And on top of that, they cost next to nothing!
To plug new devices on the electrical circuit, common sense practices are required. Never connect anything directly to the batteries. Use available spare circuits, or create new one properly: add a switch panel (protected by a main fuse) offering more fuse-protected circuits and add a circuit breaker for this new switch panel.
About “marine” devices
Marine specific devices are not bad :-). Actually, manufacturers have come a long way in the recent years to offer instruments that respect open standards. WiFi and Bluetooth are now well accepted, just to name the two of them.
Still, water, salt, rain, sun are cruel daily companions for those devices and losing a “marine” device that costs several hundreds (€, $,or £, etc.) is always a (big) pain ; most of the time they are not design to be serviceable for various reasons (being technical or marketing). So, when possible, we like to look at alternatives. For in-cockpit fixed instruments, there is no other sane option than a using marine specific instruments.
Over the last 4 years, we had a love/hate relationship with the electronics on board. And then, you get to know a device (the XB-8000), developed and supported by very friendly company (Vesper Marine in NZ) and your faith in marine electronics is fully restored – their products are very good and improving with each software release, and their support is great.
About handheld devices
Thanks to our NMEA to WiFi gateway, our phones, naviagation phablet and tablet can act as navigation instruments (we chose them waterproof, to be on the safe side). They makes precious secondary devices, should the chart plotter fail or the main GPS go crazy. Also, these devices use a different set of charts than the main chart plotter (redundancy!). Last but not least, they have a legal purpose: of the 3 sets of charts on board (2 in electronic format, 1 in paper format), these charts are the only ones on board that are maintained up-to-date. Yes, you guess right, marine charts are expensive.
One of the most useful handheld device we have on board is a phablet (Sony Z Ultra, waterproof, with a rubber case). When looking for the best spot to drop anchor, if gives detailed soundings of the area (from the Navionics charts) and shows the depth from the transducer in real time (from the NMEA gateway). No need to shout from the bow to get the data. The size of the screen (6.4″) makes it ideal to carry around and to check charts on a decent screen.
Computers and software
To charge our laptops, we are in the process of setting up a fixed 19V circuit on board (using a spare circuit on the switch panel, a 12V to 19V DC/DC step up converter – aka: car adapter for laptops – with specific outlets/plugs). We will be able to activate the 19V circuit easily without any inverter involved: we think that the “12V DC -> 240 V AC -> 19V DC” route is not the smartest way to go. Also, a few other devices on board can charge with a 19V DC circuit (the kitchen’s blender!)
Software on board
This is a personal choice, we have never been quite comfortable with Apple or Microsoft products, so we stick to Linux (Gentoo, Kubuntu) and Android. Counting our phones (2), the phablet, the tablet, our laptops (2), the navigation computer, the XB-8000… that is 8 linux kernels running on board 🙂
For navigation, we like OpenCPN, zyGrib, XEphem on the computers (laptops and navigation). The WatchMate application from Vesper Marine works really well to get all AIS (and instruments: depth, wind, etc.) related information from anywhere on board.
Did we miss something? Are we doing something totally wrong?
Feel free to leave a comment below!