Understanding your narrowboat’s electrical system is key to comfortable and reliable life on the water.
Whether you’re cruising full-time or enjoying weekends aboard, choosing the right setup can make a huge difference to performance, cost, and convenience.
This guide breaks down the essentials of low voltage systems, generating 230V power, and the pros and cons of each option.
Low Voltage Cabin Electrics (12V vs 24V)
Most narrowboats rely on a low voltage DC system for lighting, pumps, and everyday onboard equipment.
12V Systems
Advantages
- Wide range of compatible equipment readily available
- Easier to source parts and accessories
Disadvantages
- Voltage drop can become an issue over long cable runs
- May require thicker cabling to compensate
24V Systems
Advantages
- Reduced voltage drop, even over longer distances
- Smaller cables required, helping reduce installation costs
Disadvantages
- Not all equipment is available in 24V
- Some components may be harder to source
Generating 230V Power on a Narrowboat
To run household-style appliances, you’ll need a way to generate 230V AC power. There are three main approaches:
- Separate generator
- Engine-driven generator
- Inverter system (battery-powered)
The key consideration is total wattage demand. Think about:
- The size (watts) of each appliance
- How many items you’ll run at the same time
⚠️ Note: It breaches Canal & River Trust licence conditions to run a generator or engine between 8pm and 8am when moored.
Other Electric Types
Portable suitcase style separate generator
Advantages
- Lower upfront cost
- Easy to retrofit
- Typically provide clean sine wave output
Disadvantages
- Limited output (often under 1000W)
- Petrol models require special storage to meet Boat Safety Scheme rules
- Gas versions are safer but less convenient
- Only recharge batteries via a mains charger
Built-in Diesel Generators (Combustion Engine)
Advantages
- High output (typically 3000W+)
- Simple operation, just switch on
- Can run from the main fuel tank
- Provides power even if the main engine fails
- Produces clean sine wave electricity
Disadvantages
- Expensive to install
- Often difficult or impossible to retrofit
- Can be noisy, especially air-cooled units
- Requires additional servicing
- Uses similar fuel regardless of load
Built-in separate generator - diesel Stirling engine
Advantages
- Almost silent
- ‘Free’ hot water & central heating
- Plenty of power – usually 3000w or more
- Just switch on and run
- Fuelled from the main or separate tank
- If main engine broken can still have 230V power
- Sine wave supply
Disadvantages
- Very expensive to fit
- Often not possible to retro fit
- The generator is a DC unit charging the batteries for an inverter
- 2 engines to service etc
- Uses almost the same amount of fuel regardless of the load
Engine-driven 230V generator
Advantages
- Cheaper than separate, built-in generator
- Running and servicing costs for 1 engine only
- Usually 3500W supply when engine running at 1700 rpm – 1000W at about 1100rpm
- ‘Free’ mains power when travelling
Disadvantages
- If main engine breaks down, no means of charging batteries & no 230V
- Not always compatible with modern 3-stage mains battery chargers
- Older units not pure sine wave
Inverters
Advantages
- Silent mains power any time
- Cheaper than built in diesel generators
- ‘Free’ mains power when travelling
- When using high power equipment with a large inverter, running the engine at the same time, especially if there are two alternators, means the unit acts like a 230V alternator
Disadvantages
- If main engine breaks down, no means of charging batteries & no 230V
- Not always compatible with modern 3-stage mains battery chargers
- Older units not pure sine wave
