Hotel Loads That Hurt: 14 Aux Power Fixes During Port Stays

Cold-ironing lets you shut auxiliaries at berth. The decision is simple math: compare the terminal’s shore tariff ($/kWh) to your onboard $ per kWh (fuel + wear) at the expected hotel load and hours.

Aux engines are most efficient when each online set sits in its sweet spot (typically ~60–75% load). Running too many sets at light load wastes fuel; running too few pushes you past safe margins. The trick: consolidate hotel load onto the fewest sets that still keep your spinning reserve.

Your exhaust-gas economizers (from aux engines in port) can cover a surprising share of hotel steam/hot-water demand. Every kW of waste heat used is a kW you don’t have to buy back with an oil-fired donkey boiler. Prioritize economizer output, then trim the load (setpoints, tracing), and only fire the boiler for the shortfall.

At berth, HVAC can be a top hotel load. The fastest savings come from zoning off unused spaces, relaxing setpoints by 2–3 °C, and reducing outside air(within safety & class limits). That lowers both fan power and cooling/heating duty.

Deck floods, passageways, and mast/house lights are easy hotel-load wins at berth. Zone banks you don’t need, dim what must stay on, and swap to LED as fixtures fail. Keep safety/ISPS lighting on; everything else should follow a port-side lighting plan.

Centrifugal pumps waste energy when you meet a low flow by throttling and still run continuously. Two fast fixes: duty-cycle (burst-run with safe pressure bands) and VFD control (slow the pump; power falls roughly with the cube of flow). Often the best move is fewer pumps online, each nearer its efficient point.

Alongside, it’s often cheaper to buy shore water and shut freshwater makers, especially if power is pricey or your evaporator needs boiler steam. Do the math each call: compare the terminal’s $ per m³ (plus any connection fee) to your own $/m³ for RO or Evap.

Leaks and overpressure quietly burn power. Many ships run with 20–30%+ leak losses and carry header setpoints higher than needed for tools and valves. Fixing leaks and trimming pressure a few bar can deliver quick, measurable kWh savings at berth.

Reefer banks can dominate hotel load alongside. Three moves pay fast: sanity-check setpoints (avoid over-tight temps), pre-cool cargo/boxes before arrival so compressors rest at berth, and stagger defrost windows to flatten peaks (often allowing one fewer genset online).

Cranes, winches, and HPUs often sit energized between shifts, bleeding power into relief/standby losses and oil heaters. The simple win: isolate idle circuits and tighten standby pressure bands. Add a small warm-up allowance for safe restarts—net savings usually dwarf the penalty.

Alongside, you don’t need a “sea-going” bridge. Keep only the mandated minimum energized (per SMS/Flag/Class/Port), and put non-critical screens into sleep. One radar typically suffices, ECDIS/Conning down to a single display, and auxiliary workstations can sleep. The rest—off.

Galley ovens/steamers, dishwashers and the laundry bank can spike hotel load in port. The win is simple: batch jobs into off-peak hours and stagger what stays in peak. You’ll usually lower both your energy cost (TOU tariffs) and peak kW enough to run one fewer genset.

Heavy fuels need heat for pumpability—but non-pumping tanks at berth often run hotter than necessary. Reducing setpoints a few degrees and pausing recirculation where safe trims boiler/electric load without affecting departure readiness.

Trickle chargers, tool power packs, idle IT gear, forgotten work lights—small “always-on” consumers add up. A simple power-down & charging policy turns 24/7 trickle into scheduled bursts.