Marine Hotel Load Guide
The hotel load is the foundation of every marine battery calculation. It determines how large your battery bank must be, how long it will last between charges, and what charging system you need. Accurately inventorying and calculating your boat's hotel loads is the single most important step in marine electrical planning.
What Are Hotel Loads?
Hotel loads encompass every electrical device that draws power from the house battery bank when the engines are off. Unlike cruising loads, where the alternator provides charge input, hotel loads represent the worst-case scenario — the battery bank is the sole energy source for all onboard systems during anchored operation, typically 12–18 hours overnight.
The hotel load includes continuous draws (refrigeration, anchor light, bilge pump controller), intermittent loads (cabin lights, water pump, VHF radio), and parasitic draws (battery monitors, clock circuits, alarm systems). Each category must be captured in your inventory to produce an accurate total.
Typical Yacht and Cruiser Hotel Loads
The following table provides typical power consumption for common hotel loads on recreational boats and cruisers. Values assume modern LED lighting and efficient electronics. Older systems with incandescent lighting and analog instruments will draw significantly more power.
| Appliance | Power (W) | Daily Hours | Daily Wh |
|---|---|---|---|
| Refrigerator | 40–80 | 12–16 (cycles) | 480–1,280 |
| Cabin lights (LED) | 20–40 | 4–6 | 80–240 |
| Navigation lights (LED) | 5–15 | 10–12 | 50–180 |
| Fish finder / chartplotter | 15–30 | 8–12 | 120–360 |
| VHF radio | 5–25 | 2–4 | 10–100 |
| Water pump | 5–10 | 0.5–1 | 5–10 |
| Bilge pump | 20–40 | 0.1–0.5 | 2–20 |
| Anchor light (LED) | 5–10 | 12 | 60–120 |
| Instrument panel | 10–30 | 8–12 | 80–360 |
| Parasitic draws | 5–20 | 24 | 120–480 |
Hotel Load Calculation
Sum the watt-hours for every device. For cycling loads (refrigeration, bilge pump), estimate the average duty cycle rather than using continuous power rating.
The average continuous load is useful for comparing against alternator output and solar generation capacity.
Worked Example: 34-Foot Cabin Cruiser
Scenario: Inventory the overnight hotel loads for a 34-foot cabin cruiser anchored for 14 hours.
| Load | Power | Hours | Wh |
|---|---|---|---|
| Refrigerator | 60 W | 14 h | 840 Wh |
| Cabin lights | 30 W | 5 h | 150 Wh |
| Anchor light | 8 W | 12 h | 96 Wh |
| VHF radio | 8 W | 2 h | 16 Wh |
| Chartplotter | 20 W | 4 h | 80 Wh |
| Bilge pump | 25 W | 0.5 h | 12 Wh |
| Parasitic | 10 W | 14 h | 140 Wh |
Total overnight hotel load:
Average continuous load:
This 95W average is well within the capacity of a 200Ah AGM bank (1,200 Wh usable at 50% DoD) or a 150Ah LFP bank (1,536 Wh usable at 80% DoD). The alternator can fully recharge the bank during a few hours of cruising.
Measuring Your Actual Loads
DC Clamp Meter
Clamp around individual positive cables to measure current draw of specific circuits. Record readings with loads on and off to isolate each device's contribution to the hotel load.
Battery Monitor Shunt
Install a shunt-based battery monitor (Victron, Mastervolt) on the house bank. It provides real-time current, voltage, and Wh consumption data for the entire bank, capturing all loads including parasitic draws.
24-Hour Logging
Log hotel load data over a full 24-hour cycle. Refrigeration cycling, varying lighting use, and intermittent pump operation create significant variation. A single snapshot reading will not capture the true daily consumption.
Seasonal Variation
Hotel loads change with seasons. Winter cruising uses more lighting and heating; summer adds refrigeration cycling and potential cooling loads. Plan for the worst-case season when sizing your battery bank.
Try It
Use the Marine Battery Sizing Calculator to input your hotel loads and get a bank recommendation.
Open Marine Battery Sizing CalculatorNext Step
Use the Battery Sizing Calculator for a general-purpose bank sizing approach applicable to marine systems.
Open Battery Sizing CalculatorRelated Articles
The complete method for sizing a marine house battery bank using your hotel load inventory as the foundation.
Complete battery planning for yachts — hotel loads, navigation, anchoring vs cruising modes, and multi-day trip planning.
Frequently Asked Questions
What is a marine hotel load?
A marine hotel load is the total electrical power consumed by all onboard systems when the engines are off — lights, refrigeration, electronics, pumps, communication equipment, and any other devices drawing from the house battery bank. It represents the baseline energy demand during anchored or in-port operation.
How do I measure my boat's hotel load?
Use a DC clamp meter or battery monitor with a shunt to measure current draw at the battery bank. Record readings with different load combinations to build a complete profile. Measure at different times of day to capture refrigeration cycling and varying use patterns.
What is the average hotel load on a 40-foot cruiser?
A typical 40-foot cruiser with LED lighting, modern electronics, and standard galley equipment draws 80–150W continuously, consuming 1.0–1.8 kWh per day. Larger yachts with watermakers, air conditioning, or extensive entertainment systems can draw 200–400W continuously.
How does hotel load affect battery bank size?
Hotel load directly determines battery bank size: higher loads require larger banks for the same autonomy period. A 100W hotel load over 14 hours consumes 1,400 Wh. At 12V with 50% DoD (AGM), this requires a 233Ah bank. Reducing loads through LED lighting and efficient appliances reduces the required bank size proportionally.