Watermakers and Solar Power (not only) for Catamarans in 2023

Sailing across vast oceans on a catamaran is a dream for many, but it comes with its challenges. One of the main concerns while on a long-distance voyage is the availability of fresh water and power. With the advancements in technology, watermakers and solar power have become essential equipment for modern sailors. In this guide, we will explore different types of watermakers and how much solar power a catamaran should have to sail long distances sustainably. 

Solarpanels on Moonwave


If you're planning a long-distance sailing trip on a catamaran, you'll need to make sure you have a reliable source of water. Watermakers are devices that convert seawater into freshwater, making it safe for drinking and other uses. 

Reverse Osmosis Watermakers

A reverse osmosis watermaker is a device that uses a semipermeable membrane to remove salt and other impurities from seawater, producing fresh water. The process of reverse osmosis works by applying pressure to the seawater, forcing it through the membrane. The membrane allows water molecules to pass through, but it blocks the passage of salt molecules. The result is fresh water that is 95-99% pure. 

Reverse osmosis watermakers are the most common type of watermaker used on boats and in other remote areas where there is no access to fresh water. They are also used in some homes and businesses.

  • They are very effective at removing salt and other impurities from water.
  • They are relatively easy to install and maintain.
  • They can be powered by a variety of sources, including electricity, solar power, and diesel generators.
  • They require power.
  • They can produce a lot of waste water.
  • The membranes can be damaged by contaminants in the water.
  • They are a bit noisy.
Overall, reverse osmosis watermakers are a reliable and effective way to produce fresh water from seawater. They are a good choice for boats, homes, and businesses that need a reliable source of fresh water. The amount of water they produce depends on the size of the unit and the pressure applied to the seawater. They need to be cleaned and maintained regularly to prevent the membranes from becoming clogged. 

Here's a list of the best watermakers in 2023:
BrandModelCapacity (GpH)Power (W)Starting Price (USD)
Rainman12V Marine1.560$3,995
SpectraNewport 400c 12V17310$18,200
SpectraVentura 12V6.372$5,900
Village MarineLWM-180 12V7.560$6,300
Sea RecoveryUltra Whisper 400 12V16.7190$3,900
GpH = Gallon per hour

Which brings us to the next step: independent power sources. One of the most annoying things about crossing an ocean is the generator. Not only is it the complete antithesis of sailing and using natural resources to travel, but it also burns money, literally.

Solar Power for Catamarans

Solar power is a clean, silent and renewable source of energy that is perfect for long-distance sailing. It can be used to power your watermaker, navigation equipment, lights, and other electrical appliances. Sounds good? Yes - and here are some key considerations for installing solar power on your catamaran.

How Much Solar Power Do You Need?

The answer is simple: as many as possible! However, the generation is restricted to installing solar panels safely and securely. Keep in mind that when you’re out on the water, you’ll face squalls and strong winds. You may even find yourself stuck in marinas during storms and hurricanes, and you don’t want your solar panels to be ripped out by the wind, damaging your or other boats.

The amount of solar power you need depends on your power consumption. Start by calculating the daily power consumption of all your electrical devices. Then, factor in the efficiency of your solar panels and batteries. As a rule of thumb, you should have enough solar power to generate 1.5 times your daily power consumption.

Solar Panel Types

There are three main types of solar panels: monocrystalline, polycrystalline, and thin-film. Monocrystalline panels are the most efficient and expensive, while polycrystalline panels are slightly less efficient but more affordable. Thin-film panels are the least efficient and cheapest option, but they are flexible and lightweight.

Here's a list of well performing solar panels:

SunPowerMaxeon 3 60-Cell34022.6%$350
RECAlpha Pure-Black 6036022.3%$320
PanasonicHIT N330 6033021.2%$300
Canadian SolarHiKu 6035022.5%$280
Jinko SolarTiger Pro 6036522.2%$270

Solar Panel Placement

The placement of your solar panels is crucial for maximizing their efficiency. Ideally, they should be placed in a location that receives direct sunlight throughout the day. On a catamaran, the best places to install solar panels are on the bimini, hardtop, or davits. We've seen even solar foil across the hulls, but they are expensive.

Solar Charge Controller

A solar charge controller is responsible for regulating the voltage and current coming from the solar panels before it reaches the batteries. This is important to protect the batteries from being overcharged or damaged. The main features are:

Voltage Regulation
The batteries on a sailing vessel are usually 12V or 24V. A solar panel can produce more than this, especially in strong sunlight. The solar charge controller ensures that the batteries are not overcharged by limiting the voltage that reaches the battery to a safe level.

Current Regulation
It also regulates the current to ensure the battery is not charged too quickly, which can cause overheating and damage.

Prevent Reverse Current
At night, when the solar panels are not producing electricity, the charge controller prevents the batteries from discharging back through the solar panels.

Display and Monitoring
Many solar charge controllers come with displays that show the current state of the charge, voltage, and other important information. Some also have remote monitoring capabilities.

There are two main types of solar charge controllers: Maximum Power Point Tracking (MPPT) and Pulse Width Modulation (PWM). MPPT controllers are more efficient and provide up to 30% more power compared to PWM controllers. However, they are also more expensive. For long distance sailing, an MPPT controller is usually recommended.

It is important to choose a solar charge controller that is suitable for the marine environment, which can be harsh with salt water, high humidity, and strong UV rays. Also, the size of the solar charge controller should be matched with the solar panel array and battery bank.
BrandModelMax. In VoltageMax. Out CurrentPrice
Victron EnergyBlueSolar MPPT 75/1575V15A$229
EpeverTracer MPPT 40A150V40A$149
RenogyRover 40A150V40A$139
MorningstarSunSaver 40150V40A$199
Samlex SolarCS40150V40A$169

Battery Storage for Catamarans

Having adequate battery storage is crucial for storing the solar energy generated during the day for use at night or during cloudy periods. The amount of battery storage you need depends on your daily power consumption and the number of days you want to be self-sufficient without sunshine.  As a rule of thumb, your battery storage capacity should be at least 3-4 times your daily power consumption to account for cloudy days and to avoid depleting your batteries below 50% capacity, which can reduce their lifespan.

Types of Batteries

There are several types of batteries suitable for marine use, but we clearly recommend Lithium-Ion Batteries: These are the most advanced and efficient type of batteries available. They have a high energy density, long lifespan, and are maintenance-free. However, they are also the most expensive. And of course, here the alternatives:

Lead-Acid Batteries 
These are the most common and affordable type of batteries used on boats. However, they have a lower energy density, require regular maintenance, and have a shorter lifespan compared to other battery types.

AGM (Absorbent Glass Mat) Batteries
These are a type of lead-acid battery that is sealed and maintenance-free. They have a higher energy density and longer lifespan compared to regular lead-acid batteries. Although they are a good choice at the first view, they have a shorter lifespan as Lithium-Ion batteries.

Gel Batteries 
These are similar to AGM batteries but use a gel electrolyte. They are maintenance-free and have a longer lifespan but are more expensive as Lithium-Ion. 

For most catamarans, lithium-ion batteries are the best choice due to their high energy density, long lifespan, and maintenance-free operation. However, if you are on a tight budget, AGM batteries are a good compromise between cost, efficiency, and lifespan.

Here are some batteries you can take into consideration when retrofit a catamaran or sailing boat:
BrandModelCapacity (Ah)Price
Victron EnergyEnergySafe 12.812.8$2,999
Battle Born BatteriesDeep Cycle LiFePO4 12V 100Ah100$1,999
RenogyLithium Iron Phosphate Deep Cycle Battery 12V 100Ah100$1,899
EpeverLiFePO4 Deep Cycle Battery 12V 100Ah100$1,799
MorningstarRV Series 12V 100Ah100$1,699


Watermakers and solar power are essential equipment for sailing long distances sustainably. With the right setup, you can ensure a steady supply of fresh water and power while minimizing your environmental impact. Remember to consider your power consumption, solar panel type, and placement when planning your solar power setup. Choose a watermaker that suits your boat size and power availability, and select battery storage that matches your daily power consumption and desired autonomy. Happy and sustainable sailing! 

See you at the next port,
Alex + Alex