Guides to boat power and equipment
Advice from Jan at SejlStrøm
Find the answer before choosing equipment
I have gathered help here to choose, plan, and understand the equipment on board. Start with the topic you are working on, or use a calculator to get concrete figures for your solution.
74 guides · 6 topics · 2 calculators
Get a grip on power requirements
Start with the appliances and time spent on board.
Open power and solar calculator →Examine cable selection
Calculate voltage drop as part of your planning.
Open cable calculator →Choose your diesel heater
See what price, equipment, and service mean for your choice.
Compare four brands →Batteries and charging 16 guides
Choose battery, charging, and monitoring that work together.
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What size battery do I need in the boat?
Calculate from Wh per day to usable battery capacity, and check BMS, inverter, and high-load appliances at the same time.
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Victron Orion XS or Orion-Tr Smart?
Compare voltage, charging current, isolation, and system integration before choosing your DC-DC charger.
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Can solar panels, generator, and shore power charge simultaneously?
Understand the interaction between multiple charging sources, the battery's current limit, and the power the boat is using at the same time.
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What does the battery BMS do – and what should the rest of the system do?
Understand BMS, current limits, temperature protection, and the difference between battery protection and general monitoring.
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Multiple batteries in the same bank – what needs to match?
Understand series and parallel connections, and get a checklist for expanding your battery bank without overlooking the BMS and connections.
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Starter battery and house battery – keep track of their tasks
Plan the tasks, charging, and disconnection of battery banks so that general consumption does not unintentionally drain the starter battery.
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Monitor the boat's power from home with Victron GX and VRM
Understand the connection between measurements, GX device, internet, and VRM before choosing remote monitoring.
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DC-DC charger or charging relay – what suits your boat?
Understand the difference between a DC-DC charger and a charging relay. Manage your generator, battery type, charging current, and total budget.
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Choose a battery charger for shore power – voltage, amps, and charging profile
Select a 230V battery charger that matches your battery bank, consumption, and time spent in the harbor. See also what multiple charging outputs mean.
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SmartShunt and battery monitoring – understand the power on board
Understand the difference between voltage, current, and calculated battery percentage. Read about what a shunt measures and why connection and setup are crucial.
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Lithium or AGM?
Compare battery types for your consumption and budget.
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Lithium battery lifespan
Read about the factors that affect the battery.
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Battery for electric motor
Choose based on the motor's voltage and power requirements.
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Lithium batteries in the cold
Understand the importance of temperature for use and charging.
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Battery drains quickly
Get help investigating consumption and charging.
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Errors when installing lithium
Read about system compatibility and planning.
Power and installation 12 guides
Plan consumption, voltage, inverter, cables, and protection.
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Victron MultiPlus or separate inverter and battery charger?
Understand the difference between a combined inverter/charger and separate units before building your 230V system.
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Bow thruster: battery, cable, and fuse
Plan CCA, total cable length, cable cross-section, fuse, and master switch as one system.
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Shore power at 6, 10, or 16 amps – what can you use?
Convert the harbor's amps into a practical power budget, and understand how charging and appliances share the power.
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Galvanic isolator or isolation transformer – what is the difference?
Understand the two solutions for shore power, and what information is needed to choose the right one.
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Buying a used boat – check electrical and installations before deciding
Use a practical checklist for documentation, demonstration, and professional review of the equipment on a used boat.
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Choose an inverter – watts, VA, start current, and battery consumption
Get a grip on the inverter's continuous power, start load, and battery power consumption before choosing 230V on board.
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Fuses in 12V and 24V systems – what must match?
Understand fuse amps, DC voltage, and breaking capacity, and why cable calculation alone does not determine the choice of fuse.
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Cable selection and voltage drop
Find the basis for choosing cables.
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12V, 24V, or 48V?
Understand the choice of system voltage.
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Prepare the boat's power for the season
Review the installation before the first trips.
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Overview of the boat's electrical system
See the connection between battery, chargers, and consumption.
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Typical mistakes in electrical installations
Read about connections, cables, and protection.
Solar panels 9 guides
Make panels, regulator, and placement fit your journey.
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How many watts of solar panels do I need on the boat?
Start with your daily consumption, space, and season rather than a random wattage number.
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Flexible or fixed solar panel for boat?
Compare mounting, weight, ventilation, shading, and possibility for future replacement.
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MPPT or PWM – which regulator should you choose?
Understand the difference in how the regulators work and when MPPT or PWM makes sense.
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Wind turbine or solar panels – or both?
Evaluate wind, shade, charging sources, and battery before combining wind and solar.
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Choose MPPT charge regulator – understand volts, amps, and panel data
How to read the MPPT regulator's labeling and check battery voltage, the panels' Voc, short-circuit current, and charging power.
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Solar panels in series or parallel – choose based on placement and regulator
See the difference between series and parallel connection with a simple calculation example. Get a grip on voltage, current, shade, and expansion.
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Calculate power consumption and solar needs
Get an overview of the energy your trip requires.
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Solar panels not charging enough
Review potential causes for low charging.
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Typical mistakes in solar setups
Review choice of components and installation.
Diesel heating 16 guides
Compare brands, choose size, and plan heating on the boat.
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How much power does a diesel heater use?
Convert the heater's watts to battery consumption and understand the difference between stable operation and startup.
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How much diesel does a diesel heater use?
Use model data and realistic operating time to calculate daily consumption and tank needs.
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Toolbox or split diesel heater?
Choose based on location, fixed or portable installation, air distribution, and service access.
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Fuel for diesel heaters – diesel, HVO100, and GTL
See why the fuel must be approved for the specific model before you change the type.
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Complete AUTOTERM installation in boat – what to include?
Get an overview of heater, air, diesel, exhaust, power, and controls before ordering a complete solution.
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Air heating or hydronic heating in the boat – what suits you?
Compare ducting, heat distribution, hot water, and the scope of installation before choosing a heating system.
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Replacing an old diesel heater – what parts can be reused?
Review the existing system so you can get a realistic quote for replacement and potential reuse.
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Webasto, AUTOTERM, Sunster, or VEVOR?
Compare price examples, equipment, and service options.
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Hot air hoses and vents – plan diesel heating on board
Plan air distribution from the diesel heater with space for hoses, branches, and vents. See specific requirements for AUTOTERM Air 2D and 4D.
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Controlling diesel heaters – panel, Bluetooth, WiFi & GSM
Choose controls based on daily life: local operation, temperature, timer, or remote start. See the difference between Bluetooth, WiFi, and cellular.
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Which diesel heater should I choose? 2, 5, or 8 kW
Get an overview of needs, consumption, and choice of heater.
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How large a diesel heater does the boat need?
Read about boat size, insulation, and usage patterns.
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Noise from the diesel heater
Investigate placement, vibrations, and installation.
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Condensation in the boat
Understand moisture, ventilation, and heating.
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Smell from the diesel heater
Get an overview of possible causes and next steps.
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Troubleshooting diesel heaters – start, smoke, stop, and error codes
Find help for starting, operation, smoke, stopping, and model-specific error codes.
Cooling and water 11 guides
Find help for cooling, pumps, and comfort on board.
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Air conditioning in a boat – can the battery handle it?
Calculate electrical power, inverter, battery, and charging before choosing air conditioning.
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Hot water in the boat – 230V, engine heat, or diesel?
Compare immersion heater, engine cooling water, and diesel-based hydronic heating according to your usage pattern.
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Hot water with AUTOTERM combiBOIL – which solution fits?
Choose combiBOIL based on space, water consumption, heat source, and boat power supply. See an example of power consumption.
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Winterizing the boat's water system – make a plan for all water pockets
Identify parts of the freshwater system that require separate winter preparation, and create a list for autumn and spring.
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Choose bilge pump and level alarm – consider the entire installation
Evaluate pump performance, lift height, hose routing, automatic start, and alarm as parts of the same bilge solution.
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How much power does the fridge use? Calculate your battery budget
Calculate the fridge's daily consumption in Wh and Ah. See the difference between compressor power and actual consumption over a 24-hour period.
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Choosing a fridge for the boat
Clarify space, needs, and type.
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Which cooler box?
Find a cooling solution that suits your usage.
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Choosing a pressurized water pump
Look at water demand, pressure, and installation.
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Problems with pressurized water pumps
Investigate noise, pressure, and other operational issues.
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Build a stable water system
Get an overview of the pump and the parts surrounding it.
Need parts that fit your boat?
Send me model names, pictures, and a brief description of what you want to achieve. Then I will help you find a solution and ensure you get the necessary parts.
Ask Jan →Installation of diesel heater · Service on diesel heaters · Articles by release date