A canal-boat system that passes the BSS and holds up aboard.
Liveaboard life runs on the battery bank — fridge, lights, pumps, all day every day. Wattonomy sizes your bank and solar to real liveaboard use, and specs the isolators, fusing and cabling the Boat Safety Scheme examines.
A real Wattonomy output — a liveaboard narrowboat bank
System
12 V
Battery
5.12 kWh
Solar
2000 W
Inverter
MP 12/1600
SmartSolar 150/1002×
200W solar panel10×
Battery → inverter cable4×
Battery → inverter fuse1×
Wire & fuse sizes follow Boat Safety Scheme — each conductor carries its fuse and stays under a 3% voltage drop.
Built to UK (BSS) standards
Gauge · fuse · volt-drop sized
Every spec sourced
A boat fire usually starts at the wiring.
Undersized cable, missing fusing or a battery that cannot be isolated are exactly what the Boat Safety Scheme checks for — and what causes boat fires. Wattonomy sizes every conductor to carry its fuse, puts a main isolator on the bank, and shows the fusing a BSS examiner will look for.
What a narrowboat system has to get right
Full-time aboard, on a network with its own safety regime.
House bank
Sized to liveaboard days (about 2.5-3 kWh/day; widebeams more) on honest lithium depth-of-discharge.
Isolation & fusing
A main battery isolator and per-circuit fusing — the heart of a BSS electrical pass.
Charging mix
Solar plus alternator/shore charging balanced for grey canal winters.
Sized, secured wiring
Cable gauged for current and voltage drop; batteries secured and ventilated, per BSS Part 3.
What you walk away with — free
A house-bank + solar design sized to liveaboard use
A wiring diagram with isolation and per-circuit fusing
BSS-aware cabling, fusing and battery securing
A parts list you can take to any chandlery
Building it for real? Unlock the build binder.
Free gets you a safe, correctly-sized design. The build binder gets you the documents to build it right — and prove it's right.
Printable wiring diagram, yours to keep & tape inside the boat
Full parts list, every line sourced
The volt-drop & fusing calculation trail — the "why" behind every spec
The build binder is a one-time unlock — no subscription, no auto-renew.
Questions
Will it help me pass the BSS?
It sizes the cabling, fusing and isolation the Boat Safety Scheme Part 3 examines and shows the reasoning, so you or your fitter can check it. It is a design aid, not a BSS examination.
How big a bank for liveaboard?
Typical narrowboats use about 2.5-3 kWh/day, widebeams 4-5 — enter your real loads and it sizes the bank, solar and wiring around them.
Solar or engine charging?
Both — solar helps spring to autumn; the engine alternator and shore power carry the grey winter months, balanced in the design.
Do I need an account?
No — free, no email. Accounts only for saving builds or the build binder.
The standards we build to
Plain version: these are the recognized rulebooks your design is sized against, so the numbers hold up to a surveyor, an inspector or an insurer.
Boat Safety SchemeThe UK safety examination for inland/canal boats (electrics in Part 3).
BS 7671The UK IET Wiring Regulations for the 230 V side.
Wattonomy applies these standards in its calculations. It is not certified, sponsored or endorsed by ABYC, ISO, NFPA or Victron — it sizes your design to meet what they require, and shows the working.
Sized and checked to BS 7671. Last reviewed June 2026 — see the full methodology for the exact rules behind every number and how each design is validated.
Built by anABYC Certified Master Technician