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When asking Claude if there are better tools for such a task this came back:

For this specific job — a marine DC wiring/schematic diagram with fuses, switches, motors and bus bars — draw.io is actually a fine choice and it's what most people land on for free schematic work, but it's a generic diagramming tool: the "electrical" shapes it ships with are pretty basic, which is why I had to approximate fuses and switches with plain rectangles and circles in the file I gave you.

If you want something built specifically for this kind of diagram, free and open source, two options stand out:

QElectroTech is the closest match to what you're actually doing. It's a free, open-source (GPL) editor made specifically for electrical/industrial wiring diagrams — it ships with real symbol libraries for fuses, contactors, relays, motors, terminal blocks, and lets you build multi-page projects with proper cross-references between sheets, which is exactly the style of the Jet-Tern drawing you uploaded. Runs on Windows, Mac and Linux. Downside: smaller community than draw.io, and the interface is a bit more old-school CAD than modern web-app.

KiCad is the other free heavyweight, but it's really built for circuit schematic capture and PCB design (nets, footprints, ERC checks) rather than a "poster-style" one-page wiring diagram like this one. It has excellent symbol libraries but a much steeper learning curve for something like a battery-charging layout — probably overkill here.

A middle path worth knowing: draw.io itself does have a proper "Electrical" shape category (batteries, switches, relays, fuses, ground symbols) that I didn't use in the file I built — I stuck to generic rectangles/ellipses so the XML would be simple and robust. If you'd rather stay in the file I already gave you, I can swap the fuse/switch/motor placeholders for draw.io's real electrical stencils, which would get you most of the visual fidelity of QElectroTech without switching tools or losing the layout work already done.

Want me to do that swap, or would you rather I rebuild the diagram in QElectroTech's own file format?

Sources:

QElectroTech – Free electrical diagram software (Windows, Mac, Linux)

Download QElectroTech – Windows, Mac, Linux

QElectroTech: An Open Source Wiring Diagram Tool | Hackaday

So I will also try now QElectroTech ;-))

Harald Raetzsch

Selene 66 Mazu

I had a similar problem regarding electricity drawings and drawings in general. The original documentation on Mazu was apparently created using AutoCad long time ago. I scanned all pages and when the yard needed the electricity schematics I fed the page into Claude / Anthrophic to create an editable version for drawio. I attached the original page and the result from the AI conversion. It is not perfect but saved a lot of time compared to redrawing it.

Here is what Claude reported after the conversion:

I've redrawn the whole schematic as an editable draw.io file. Open it at app.diagrams.net (File → Open From → Device) or in the draw.io desktop app / VS Code extension.

What's in it, matching the original JTSE66TE-0618 drawing:

BC1–BC3 chargers (MASS 24/100) and the 5kW inverter, each fused (100A/100A/325A/125A) onto the positive bus bar

Windlass, port/stbd capstans, davit and DC-loads branches with their fuses, overload breakers and motors

The HB "1/BOTH/2" selector feeding the house bank through two 400A fuses (HB1/HB2)

The house battery bank itself: 24 × 2V/1000Ah cells as two 12-cell series strings in parallel (2000Ah @ 24V), wired in the same snake pattern as the original

The negative bus bar and main negative disconnect

BC4 (MASS 24/75) → Battery Mate 1603 combiner → BC5/BC6/BC7 (80A each) feeding the Port/Stbd/Generator starting batteries

The Manual Emergency Parallel Switch tying the DC-loads line to the starting-battery bus

MS1/MS2/GS switches, the engine/generator blocks with G/M symbols, and the title block + notice text from the original sheet

Everything is native draw.io shapes (rectangles, ellipses, fuse blocks, colored wires — red for DC+, blue for DC−), so you can move, relabel, or recolor any element directly. A couple of internal wiring details (e.g., exactly which fuse feeds which string) were inferred from the drawing's layout since the scan doesn't spell them out in text — worth a quick visual sanity-check against the PDF before you rely on it.

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Harald Raetzsch

Selene 66 Mazu

I'm attaching the antenna drawing which will need to be updated after I put my Starlink antenna up on the arch.

Regarding the N2K network. You could create a separate drawing just for the network showing where the power comes from and what's attached to it without going into all the detail of each of the components.

After graduating college in 1982 I started my first engineering job an an equipment design engineer. My employer had just contracted to buy a $250K CAD system. Since I was the "kid" they sent me to Palo Alto to learn how to use it. It was complicated back then, and in many ways it hasn't gotten a lot simpler, just less expensive. It was the start of the tech boom (Apple was accelerating, Intel was booming, PCs were selling). I was impressed with the number of Ferraris and Porsches in the parking lots!

Richard Nye

Untethered, 57-22

https://forecast.predictwind.com/tracking/display/MV_Untethered/

Hi Richard,

Great inspiration for drawing up simple pages denoting the individual electronic equipment.

I’m not sure it’s necessary to map out an entire N2K network if the pieces are well illustrated individually. I expect it is universally understood that a well designed N2K network has a backbone, end terminals, and power supply in accordance with LEN requirements.

So I’m not gonna do it.

I’m going to follow your lead and show just the individual equipment on the N2K network.

I’m going to use the same approach for my Garmin Blue network and associated Garmin equipment.

Unfortunately your antenna image didn’t load.

John

I would be nice if Jet Tern could supply the CAD files in a format that we can modify. In my case, the electrical drawings on a 2005 boat were very basic. The electronics (chart plotters, instruments, etc.) were drawn by the company that did the installation, and were quite good. But I have made several changes since I've owned the boat and needed to document the changes.

The approach I'm taking is creating one drawing per electronic instrument. In the attached case it's the AIS. The drawing shows where the power comes from, what's attached to it, and even some documentation about how it was programmed. I wanted to steer away from a large drawing with multiple instruments on it that gets complicated and needs to be constantly updated.

At one point I tried using AI to create some Victron schematics. Every time I tried to make a small change AI would change something else and eventually created a Frankenstein. I did look into Wireframe, but it seemed like a one trick pony and not too flexible.

Richard Nye

Untethered, 57-22

https://forecast.predictwind.com/tracking/display/MV_Untethered/

Hello Everyone,

I have been using Wireframe for a few months.

It is incredibly neat and clean. I have been using an iPad which I definitely would NOT recommend. I’m back in Portugal now so I will see how it works on an Apple laptop and desktop. I have no engineering or design training so I’m sure others would approach things in a much better fashion. I’m just a Selene cruising, motorcycle riding, retired dentist who likes to fool around with mechanical things.

I like it a lot but wish the library of Victron products was larger. I wrote to them but didn’t receive a reply. Perhaps if more of you contact them it might prompt them to add more Victron stuff.

John

I've been trying to document the electrical changes I've made. I've searched for a simple electrical drawing app that is free, or little cost, and easy to use. A couple years ago I settled on Smartdraw, but I wasn't completely satisfied. It is about $130/year and it just seemed to take me too long to make a simple drawing.

Recently I found drawio (www.drawio.com). It's free, open-source app that runs on the web or from a desktop. It's well documented, has lots of tutorials available, and pretty intuitive. It has lots of symbols for electrical or plumbing, and you can make your own if you choose. You can save the files in any number of formats including pdf. It can be used for any number of things besides electrical or plumbing.

I just thought I'd pass this on in case you were looking for a similar tool to document the boat.

Richard Nye

Untethered, 57-22

https://forecast.predictwind.com/tracking/display/MV_Untethered/