8kW class
May suit systems whose charger and simultaneous loads fit within the available continuous output. Actual current depends on voltage, efficiency and settings.
Electric and hybrid guide
Narrowboat Generator Sizing for Electric and Hybrid Systems.
Choose generator support around the charging system and cruising duty—not the largest headline output.
Start with the charger
The generator can only supply what the system can use.
The inverter-charger, battery limits and onboard loads determine how much generator output becomes useful battery charging.
01
Charging ceiling
Confirm the sustained AC input the inverter-charger can accept at the selected settings.
02
Hotel loads
Allow for appliances operating while charging rather than assuming every watt reaches the battery.
03
Duty cycle
Consider runtime, cooling, acoustic treatment and the generator's efficient operating range.
04
Installation
Plan fuel, exhaust, ventilation, service access, vibration control and electrical protection.
Why bigger can disappoint
Unused generator capacity does not shorten the charge.
If the inverter-charger or battery accepts less power than the generator can provide, the extra capacity remains unused. A larger set can also bring more weight, space, fuel consumption and acoustic treatment.
15kW class
Can support higher charging and domestic demand only where the downstream equipment is designed to use it.
Serial hybrid use
The generator replenishes the battery bank; the electric motor remains the propulsion source.
How serial hybrid works →
The complete energy budget
Size for the least convenient day, not the best one.
Winter solar, consecutive cruising, induction cooking, laundry and other simultaneous loads should be considered. That does not mean every system needs the largest generator; it means the proposed generator should be tested against a realistic operating scenario.
Questions buyers ask
Clear answers before specification.
How large should an electric narrowboat generator be?
There is no universal size. It should be matched to the inverter-charger, battery limits, simultaneous onboard loads, expected runtime and installation constraints.
Does a 15kW generator charge twice as fast as an 8kW generator?
Not necessarily. Charging cannot exceed the limits of the inverter-charger and battery system, and onboard loads also use part of the available output.
What else must be considered when installing a generator?
Fuel, exhaust, cooling, ventilation, electrical protection, acoustic treatment, vibration control and safe service access all form part of the installation.
Plan your Oakums
Turn the technical questions into the right specification.
Tell Oakums how you expect to cruise, live and recharge. We will relate the equipment choices to the boat and your intended use.