Boat manuals need to include electrical schematics and software details

Good drawings take time to make. Time costs money. Therefore, good drawings are not cheap.

Some boat builders seem to think that this logic leads to a fourth point: "Therefore, we will not include drawings."

Er, guys? Not cool. Seriously, not cool. Just see what happens the very first time the owner has to have something fixed, and the technician spends most of a day rooting around in the bilges trying to figure out where the hell all the wires are going.

Almost as bad as the boat with no drawings is the boat with inaccurate drawings. Maybe something got changed on the shop floor, maybe there are dealer-installed accessories. Whatever the cause, the result is a situation where what's acutally in the boat doesn't match what's expected. That means time and money will be wasted trying to figure it out.

The problem only gets worse as technology advances. A relatively simple modern yacht, about 12 metres (40 ft) long, might have:

  • A main panel with 20 or more DC breakers
  • Hundreds of metres of light DC power cables
  • 50 m of heavy duty (>100 amp) DC power cables
  • An NMEA 2000 bus comprising ten sensors, 50 m of N2K cable and 40 to 50 connections
  • Radar, VHF and SSB cables up the mast
  • A harness of ten or twenty wires for engine control and instrumentation
  • Battery monitoring wires for the amp-hour meter, the alternator regulator, and the shore-power charger
  • A bank or two of solar panels, plus their wiring, charge controllers and circuit breakers

For a "typical" level of complexity, you can add a couple of AC inverters (and their wiring, and breakers, and distribution panel), the control electronics for a watermaker and refrigerator, audio and video equipment, a fishfinder, and a dashboard full of the latest multi-function displays. The latest fad is distributed power systems- little black boxes that turn virtual circuit breakers on and off in response to digital commands sent over the vessel's communication bus.

There is no way anyone is going to be able to make sense of all this in five years if it isn't written down.

Furthermore, the computerized parts, such as the N2K bus and the distributed power nodes, will be simply impossible to troubleshoot later on, unless all of their configuration details- and the software tools to implement them- are provided to the owner in an appropriate format. It is for this reason that I am extremely reluctant to specify any components that require closed, proprietary computer systems for their installation and maintenance.

So, some solutions.

Equipment manufacturers: Use standard communication protocols such as NMEA 2000 wherever possible, and follow the standard (none of this "we'll add our own proprietary PGN" bull). If you have a gadget that simply must use a proprietary, non-standard protocol, then document it thoroughly- including connector pinouts, signal levels and the data format specification- and post that on your website. If proprietary software is needed to configure or troubleshoot your device, make that software available for download- or, better yet, make it an open-source project and see what cool stuff the community can create based on your devices.

Boat builders: Draw up a standard schematic for the base model of each of your boats. When a customer orders options, add them to the schematic for that boat. Make sure that what's happening on the shop floor and what's going onto paper are the same thing. Then, when the customer takes delivery, include the schematics in the owner's manual. (And, ideally, also in a format that can be amended as the boat gains new gadgets later in life.)

Owners: Keep the electrical drawings updated as you add new systems. If you don't have any drawings, go down to the boat (when you have a few hours to kill) and start making notes on how everything's connected.

Yes, drawings do require time (and therefore money) to make. And they aren't going to be complete, or correct, right off the bat: they will change as the shop crew works around problems, and as the owner requests changes and additional options. If the boat's systems are non-trivial, though, accurate drawings are essential- both to the sanity of the technicians who will visit the boat in the coming years, and to your reputation as a builder.





Hi Matt,

Great post and so true. While good drawings are the ideal situation. You can get say 80% of the benefits by numbering all wires and terminals, using the little sticky numbers than come in pads, and then making a call out sheet. I have done this with "Morgan's Cloud". It probably took 20 hours or so to do the whole boat, whereas the fairly simple drawing I made that just covers the high current DC wiring took nearly that long.

Label your wires, for sure!

Matthew's picture

Numbering the wires is a great idea.
The computer network guys figured this out a while back- I can look under my desk and instantly know that the other end of the cable is patch cord C19 on panel HDF4-0B. The network would be utterly unmaintainable without those labels, and they're very easy to make.
I would love to see boatbuilders do the same thing.

From another point of view..

Hey Matthew, I agree with you.. the electrical schematics and software details should also be included in the boat manual. Meanwhile, from my own point of view as a boat dealer from Missouri, given that the boat is high quality, etc.. the boat with a very detailed boat manual would probably sell faster than those that do not.

electrical schematics

When I labelled the wires of our recently rewired boat, I used a handheld labeller, printed two labels, then covered them with clear, adhesive shrink tubing. Each end of the wire has the same common sense label. I have been fretting about how to make computer based drawings, schematics. It's a 47' ketch with most all the stuff mentioned above. As the rewiring progressed I'd make sketches of what I was going to do. Those sketches are saved on paper. However they are a mess.

Can someone recommend an open source program that will enable me to make clean electrical schematics? I'm not an engineer, nor a programmer. I do use the Linux Mint operating system.

Thanks, Doug

Schematic software

Matthew's picture

Printed labels and clear shrink tubing - Doug, your boat must be an electrician's dream now!

For schematic software, I've recently become a fan of PCBWeb ( ), mostly because it's very easy to get started with and integrates with the DigiKey parts catalogue. I've also heard good things about TinyCAD for Linux, although I haven't used it enough to have much of an opinion.

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