Two smaller generators almost always beat one large one on a dive liveaboard. The load profile swings hard between a heavy afternoon peak and a light overnight demand, and a single set sized for the peak spends most of its life lightly loaded, which causes wet stacking, poor economy and shortened life. Split the capacity so one set can carry the normal load at a healthy load factor.
Build the load list honestly
The calculation starts with a genuine list of every electrical consumer and when it runs. On a Komodo liveaboard the significant ones are air conditioning across guest cabins and the salon, the dive compressor, the watermaker, galley equipment, refrigeration and freezers, lighting, water pressure and pumps, entertainment and charging, deck machinery, and any gyroscopic stabiliser.
Then apply realistic simultaneity. Air conditioning at mid-afternoon in the tropics with every cabin occupied is close to full load. The compressor probably runs in that same window because that is when the fills happen. That afternoon coincidence is your peak, and it is much higher than the average.
Why the split matters
A diesel generator wants to run at a substantial fraction of its rated load. Run it lightly for long periods and unburnt fuel and carbon accumulate in the exhaust system — wet stacking — which fouls the turbo and injectors, degrades performance and eventually requires intervention. It also wastes fuel per unit of energy delivered.
Two smaller sets let you run one at a good load factor for most of the day and bring the second on for the peak. They also give redundancy: a generator failure on a boat with air conditioning, refrigeration and a compressor is a trip-threatening event if there is only one machine. In a place with limited service support, that redundancy is worth more than the capital saved by a single unit.
The overnight problem
Overnight load is small — air conditioning at reduced setting, refrigeration, lighting, charging. Running a generator all night to serve it is the single biggest source of guest complaint on liveaboards after roll, because guests sleeping aboard hear and feel it. Three approaches work:
- A small night set sized close to the overnight load, run at a sensible load factor.
- Battery bank and inverter sized to carry the overnight load, charged during the day when a generator is already running.
- Solar contribution to reduce daytime generator hours and help recharge the bank — see solar and battery systems.
Removing the overnight generator run is the highest-value comfort upgrade available on most dive boats, and it costs far less to design in than to retrofit.
Loads people forget to include
Gyroscopic stabilisers, which draw significantly during spool-up and continuously in operation — see stabiliser selection. Watermaker production, which is energy intensive. Battery charging itself, which is a real load when the bank is depleted. Electric galley equipment, if the galley is not gas. And future additions: owners routinely add equipment in year two on a plant that had no headroom.
Installation details
Enclosures and vibration isolation, because generator noise transmitted into the structure will reach cabins whatever the enclosure does. Ventilation and combustion air sized for tropical ambient temperatures, not temperate ones — derating in heat is real and generators in hot, poorly ventilated compartments underperform their nameplate. Exhaust routing that keeps fumes clear of the compressor intake and of guest areas — see compressor intake placement. Accessible service points, because filters and impellers get changed frequently. And switchgear and distribution that allows load shedding in a controlled way rather than tripping the set.
Shore power
Shore power availability in the operating area is limited and its quality is variable. Specify robust protection, correct earthing and galvanic isolation, and do not design a vessel that depends on shore power being available or clean. On aluminium hulls in particular, shore power arrangements interact with corrosion protection — see aluminium hull considerations.
Getting it right on a refit
Repowering the electrical plant during a refit is common because the original sizing predated the air conditioning, the compressor upgrade and the stabiliser. Doing it properly means redoing the load list rather than fitting a larger version of what was there. Scope and sequencing are on the refit page, and the whole specification chain is on the specification guide.
Frequently asked questions
How many generators should a Komodo liveaboard have?
Two, in most cases. The load profile swings between a heavy afternoon peak and a light overnight demand, so splitting capacity lets one set run at a healthy load factor for most of the day while the second covers the peak, and it provides redundancy where service support is limited.
What is wet stacking and why does it matter on liveaboards?
It is the accumulation of unburnt fuel and carbon in the exhaust system when a diesel generator runs lightly loaded for long periods. It fouls turbo and injectors, degrades performance and wastes fuel. A single generator sized for the afternoon peak spends most of its life in exactly that condition.
How do I avoid running a generator all night?
Either fit a small night set matched to the overnight load, or size a battery bank and inverter to carry it and charge during the day while a generator is already running, ideally with solar reducing daytime generator hours. It costs far less designed in than retrofitted.
Talk to the build desk
Send the vessel details or the operating profile you want to run and we will tell you what has to be established before a number means anything. Quotations in USD. Construction, repair, refit and vessel-sale contracts are issued by PT Komodo Galangan Nusantara.