The commercial gear aboard worth naming — navigation and instruments, power and charging, batteries and their management, and the networking boxes. What each one is for and which ones are actually fitted.
The commercial side — and why it stays
This is the gear that keeps the boat off the rocks, and it is all proprietary Raymarine. That's deliberate. The argument for why is on the projects page: primary navigation should be the most boring, most reliable thing aboard, and the open-source work runs alongside it rather than instead of it.
| Part | What it does |
|---|---|
| Axiom 2 Pro helm and nav station |
The multifunction displays. Charts, radar, sonar and autopilot control, one at the outside helm and one at the nav station so you can work the boat from inside or out. |
| Quantum radar | Solid-state pulse-compression radome. Low power, no magnetron, no warm-up. Also the one we decoded onto a Raspberry Pi — it runs the MFD and our own screen at the same time. |
| EV-400 autopilot | The Evolution autopilot pack for hydraulic steering: control head, EV-1 sensor core, ACU-400 actuator control unit, rotary rudder feedback and the cabling kit. It is sold as a complete set so the calibration mostly does itself. |
| p70Rs control head | The rotary one. A 3.5 inch color head with a physical knob instead of a button pad, and it drives power steer mode — so you dial a course change in from inside the pilothouse rather than turning the wheel. Raymarine specify it for powerboat helms; on a pilothouse boat it is exactly the right control. |
| EV-1 sensor core | The autopilot's brain — a nine-axis attitude sensor that
works out heading, roll and pitch with no setup and no
calibration run. Mount it anywhere, any orientation.
What it does not measure is heave, which is why there's a second motion chip aboard. |
| RS150 GPS | Remote-mount GNSS sensor, 72 channel, GPS and GLONASS, 10 Hz position updates. Puts position on the SeaTalkng / NMEA 2000 bus so everything aboard sees the same fix. |
| RSW wind transducer | Masthead wind vane and anemometer, short arm. Apparent wind speed and angle onto the bus — which is where our own daily averages and the wind page get their numbers. |
| emTrak AIS | Class B transceiver. Sees other vessels and, importantly, makes this boat visible to them. Also the feed we give back to the public AIS networks. |
| Airmar depth transducer | Depth and water temperature, wired into the Axiom rather than straight onto the bus — which is why depth is only available when the MFD is powered. |
On a conventional sailboat you steer from the cockpit and the autopilot is mostly a push-button "hold this course" device, which is what the keypad heads are built for.
A pilothouse boat is different: a lot of the passage is spent inside, and the useful control is not "engage the pilot" but "come ten degrees to port, now" — repeatedly, while looking out of the window at a crab pot. A knob does that in one movement. A keypad makes you count button presses.
That's the whole reason for the rotary head. It isn't a powerboat affectation; it's the right interface when the knob is your helm.
Everything in the table above sits on NMEA 2000 or ethernet, which means the Raspberry Pi can listen to all of it:
None of that required permission, and none of it changes how the Raymarine gear behaves. We are reading what is already on the wire. That is the whole trick, and it's why both sides can run together.
The expensive end, and worth it
This is where most of the money on a cruising boat goes, and it's the part that decides whether everything else works. We run Victron for almost all of it, for one reason beyond the build quality: their settings are open and readable, and Venus OS, the software on their GX devices, is open source.
| Part | What it does |
|---|---|
| Fischer Panda 8 Mini diesel generator |
The boat's own power station when there's no shore and no sun. An 8 kW marine diesel genset — a two-cylinder Kubota Z482 driving a freshwater-cooled alternator, in a sound shield, rated around 52 dBA at seven meters. Peak output about 7.4 kW, continuous about 6.7 kW at 120/240 V, 60 Hz. It feeds the MultiPlus, which charges everything else. We monitor it with a Pi → |
| Victron MultiPlus 24/3000/70-50 |
Inverter and charger in one box. Makes mains from the batteries, and charges them from shore or the generator. The single most useful thing on the boat after the batteries themselves. |
| Victron Orion DC-DC chargers | Move charge from one bank to another at a voltage and current you choose, with a custom profile. Six of them aboard, and they are what makes charging lithium off a dumb alternator possible. |
| Victron MPPT solar controllers | Turn whatever the panels are making into what the bank wants. MPPT rather than PWM is worth real money on a cloudy day. |
| Victron Ekrano GX | A GX device with a 7 inch sunlight-readable touchscreen built in. Runs Venus OS — and in its Large image it ships with Signal K and Node-RED already installed. Full write-up → |
| Victron shunts | Precision resistors in the negative cable that let you measure current. Right answer for a lead-acid bank — and the wrong one for a lithium bank that already has a BMS. Why → |
| Automotive relays | A few hundred milliamps off the ignition switch controlling tens of amps of charging. Cheap, dumb, and completely reliable. How to wire one → |
| Niehoff N1387 alternator 210 A |
Standard internal regulation, charging a lead-acid buffer bank rather than the lithium directly. Untouched, deliberately. |
Four banks, two chemistries, two BMS units
| Part | What it does |
|---|---|
| LiFePO4 cells 24 V house, 12 V nav |
Lithium iron phosphate — the safe chemistry, not the cobalt one that makes the news. Takes charge fast, gives most of its capacity back, and doesn't mind being worked hard. Why we went lithium → |
| JK BMS | One per lithium bank. Reads every cell individually, balances them, watches temperature, and opens the circuit before anything gets damaged. Talks over Bluetooth or a cable. Getting one onto a Pi → |
| AGM telecom batteries | Two 12 V units in series as a 24 V buffer bank. Built to sit on float for years. Their job is to give the alternator somewhere safe to push. |
| Lead-acid start bank | Starting the Lehman. The one job lead acid is still unambiguously good at. |
| Class T fuse / main breakers | Lithium can deliver an enormous short-circuit current. The protection has to be rated for it. Not optional and not the place to save money. |
If you fit lithium, fit a BMS. Not a monitor, not a voltmeter — a real BMS with per-cell sense wires and the ability to disconnect. It is the thing standing between a wiring fault and a serious problem, and it is the cheapest part of the whole installation.
The word that keeps turning up
A multiplexer takes several data streams and combines them into one. That's the entire idea, and on a boat it exists because of a limitation in NMEA 0183.
NMEA 0183 is point to point. One talker per pair of wires, though several listeners can share that pair. There is no bus and no addressing, so no way for two devices to talk on the same cable — if two talkers transmit on the same pair at once, the sentences interleave and both are ruined.
So a boat with a GPS, a depth sounder, a wind instrument and an AIS has four separate talkers, and a chart plotter with one input. The arithmetic doesn't work.
A multiplexer has several inputs and one output. It listens to all of them at once, buffers what arrives, and sends the sentences out of the single output one after another in good order. Nothing collides, nothing is lost, and the plotter sees one tidy stream.
Most will also do a few things beyond merging:
NMEA 2000 is a bus, so it doesn't have this problem. Every device shares one backbone and the protocol handles who talks when. On an all-N2K boat there is nothing to multiplex.
What you still need is the bridge: the thing that lets an old 0183 instrument join a modern N2K boat, or lets either of them reach a tablet over WiFi.
How we use it, and what it becomes offshore
The DataHub is a small box that is three things at once: a router, an NMEA 2000 gateway, and a weather terminal. On Exodus it is the center of the whole network — everything aboard sits behind it.
| Interface | What it's for |
|---|---|
| NMEA 2000 port | Straight onto the boat's instrument backbone |
| WiFi radio #1 | Connects out to a communications device — Starlink, a marina network, a phone hotspot |
| WiFi radio #2 | Broadcasts the boat's own network to everything aboard |
| Ethernet WAN + LAN | Wired upstream and wired downstream |
| Internal GPS | With an external patch antenna, so it knows where the boat is without depending on anything else |
| 4 GB storage | On-board data logging |
Two separate radios is the detail that matters. One box is simultaneously a client on somebody else's network and the access point for yours. That's what lets it sit between the outside world and the boat instead of beside it.
Every device aboard — the Pi, the laptop, the phones, the tablets, the sensors — joins the DataHub's network. The DataHub joins whatever internet is available. Nothing aboard talks directly to the outside.
That one arrangement buys a lot:
Everything above is convenience. The reason it's fitted is what happens once the marina WiFi is a hundred miles astern.
Offshore, bandwidth stops being free. Whether it's satellite data or a metered Starlink plan, every megabyte is a decision. And the default behavior of a boat full of modern devices is appalling — phones syncing photos, laptops downloading updates, apps checking in. Untended, a crew of two can burn an offshore data allowance in an afternoon without opening a browser.
The DataHub sits in front of all of it. It filters the rubbish and fetches what you actually asked for. You tell it which forecast models you want, at what resolution, over what area, how often — and it goes and gets exactly that, compressed, and nothing else.
That is the difference between a weather routing workflow that is usable at sea and one that isn't. Not the forecast quality — the discipline about what crosses the link.
Here is the trap. You switch the Starlink data on for ten minutes to grab a forecast and check your email. The moment the link comes up, every device aboard tries to phone home at once. Phones sync photos and back up, laptops download updates, apps refresh, cloud folders catch up. None of it asks, none of it shows, and all of it comes out of your data.
The DataHub is where you stop it. Its firewall and device settings decide which devices are allowed to use the internet connection at all, so only the one doing the job you switched the link on for gets through, and everything else stays offline until you say otherwise. PredictWind's own help describes this as the Internet → Device Configuration and Firewall pages, which control how a connection like Starlink can be used by the devices on the DataHub's WiFi. PredictWind: DataHub data usage →
The habit that goes with it: switch the link on, fetch what you came for, switch it off. On the devices themselves, turn off automatic updates and photo sync, and mark the connection as metered so the system holds back big downloads.
PredictWind build the DataHub to work with Starlink, and the Pro version is specified as Starlink LTE-ready. As we move offshore the plan is for Starlink to become the upstream connection, with the DataHub still sitting between it and the boat, still deciding what goes out and what comes in.
And that's where the security lives. The boat's own network stays private behind the DataHub. Starlink faces the internet; the DataHub faces Starlink; everything aboard faces only the DataHub. One edge, one place to get right.