There are two main methods for desalination, making drinking water from seawater: distillation and filtration. Distillation boils the water into steam and condenses it back into pure water. This leaves the salt and most other contaminates behind. This process requires heat and is used on large ships. Filtration pushes the seawater through a membrane and is called reverse osmosis. This process uses high pressure and is most common on sailboats.
Reverse osmosis systems are often referred to as “watermakers” in boating and yachting circles. These usually include a strainer, one or more filters, the reverse osmosis membrane, and sometimes added charcoal and ultra Violet light. Watermakers are valued because they replace purchased water and reduce dependence on storage tanks.
The irony of living on catamaran, or indeed any sailboat, is that you have an abundance of water. You can drink a small amount of seawater but only in an emergency. You have to urinate more than you drank to get rid of the salt from the seawater. Eventually, you die of dehydration even as you become thirstier. Therefore, it’s important to learn how to make drinking water from seawater.
Do I Need a Watermaker?
For drinking, you need to have a ready source of fresh water. This can mean storing fresh water while at a marina, purchasing bottled water in a grocery, catching rainwater, or treating the seawater. All of these methods can work, but a watermaker is a better, and more permanent solution.
In this article, I’m going to cover the ways for getting a supply of fresh water on your sailboat and explain how to make drinking water from seawater.
Let’s dive right in!
If you are only out for the day, you can take your water and food along with you. And you should. They will be fresh and cold and right where you want them. And, if you are sailing along the shoreline, you can always stop and pick up supplies if you need them.
On the other hand, if you want to live aboard your boat, you will want to consider another option. There are lots of things to maintain on a sailboat, especially one that you plan to make your home. Sails, engine, generator, navigation are just a few important things. However, water is life!
With the right watermaker, the ocean becomes a vast supply of fresh and clean drinking water to keep you hydrated during your offshore sailing adventures. There are other ways of getting fresh water. In addition, if you are handy, and want to try DIY or you just want the parts, stay tuned. Because those are covered later.
Why Would I Need a Watermaker?
The other parts of a sailboat are sexier. The sails, engine, electronics, and generators often get more press, especially for long-distance voyages. Sooner or later, many serious boaters begin exploring a long term solution for drinking water.
Many sailboats, including catamarans, have freshwater drinking tanks onboard. You can fill your tanks from any source. Without a watermaker, many new boaters start by collecting rainwater. After all, it’s free and even delivered!
Of course, that is often not enough. To supplement rainwater, they often spend a night at the marina or visit a store. Of course, this can get old fast. This is when boaters get real serious about making drinking water from seawater and begin to look at watermakers.
The first reaction of most new boaters, is that watermakers are expensive. Well, yes… they can be.
What Are the Benefits of Having a Watermaker?
Let’s look at what a watermaker does. There are several stages and each of these is important to the overall process. Plus, we want to understand this, because it’s important.
Comparing the Cost of Watermakers
First, let’s compare the cost of the water you are replacing. Rainwater is free, and you don’t have to go to the store or the marina to get it. However, it does require catching. You can do this with a tarp or some other catchment system. However, if it’s not out all the time, it will require set up. Also, there isn’t any way to test rainwater.
Watermakers Replace Marina Visits
Second, the water supply at the marina is free. However, you have to put the gerry cans into the dinghy and “drive” to the source. This also means you are using the marina, which is a paid service. So, it’s semi-free but schlepping the water back and forth is going to get old.
Watermakers Replace Bottled Water and Plastic
Third, there’s the bottled water. Crystal clean, sparkly and expensive. If you are in the regular grocery, this can cost a dollar or so. That water’s going to be expensive on a remote island. I have see it cost $3 and higher per bottle. Ouch.
How Watermakers Make Drinking Water
Adding up the total cost of fresh water and multiplying that amount will give you a clear picture of the value of your watermaker. The heart of modern watermakers is the reverse osmosis membrane. A good watermaker system can produce many thousands of gallons of water for every membrane. When you compare this with the price of fresh water, a watermaker starts to make sense.
There are some really good watermakers on the market, and they are much more advanced and reliable than they used to be. For comparison, let’s explore how the watermaker makes drinking water from seawater and what’s involved.
How Does a Boat Watermaker Work?
Modern watermaker systems usually include a strainer for removing the large items. Next, is a filter (or two) for the microscopic debris. Then the part that separates the salt from the water is the reverse osmosis semi-permeable membrane at high pressure (requiring a high pressure pump and a motor). Finally, the water may be run through a charcoal filter and UV exposure to kill any remaining bacteria and viruses. Additionally, the water is tested and stored in your onboard tanks.
After considering all that a watermaker does, the costs seem much more reasonable. Besides, it’s a package.
Benefits of Having Reliable Drinking Water
Besides the cost savings, having a reliable drinking water system installed on your boat can be a relief. The system is automatic. The water is constantly tested. All you need to do is replace the filter when needed and you are good to go.
There is tremendous freedom and security that comes from having full water tanks onboard your sailboat. Water should not be something you worry about. Ocean crossings are suddenly possible and even reasonable with enough supplies and water on hand. Knowing you can make drinking water from seawater can be a good feeling.
The Basics of Modern Marine Watermakers
There are three basic power systems on sailboats, including catamarans. The engine, 110 VAC, and 12/24 VDC. Because of this, there are three different ways to power your watermaker. Generally, you can find a good brand that runs on your system. Sometimes, the brand will make three different models, one for each power source.
Besides that, solar electric is gaining ground on the wind-powered and the Diesel-powered catamarans. As solar panels become stronger and more reliable, and as the Lithium and other new batteries follow closely behind, the most common power source will be a DC system.
How Watermakers Work
The RO (reverse osmosis) membrane works under high pressure. This means that you need a pump. Because of this, the best systems will want to connect the pump directly to your engine. This will give you a reliable source of high pressure for the membrane to work properly.
This is generally more productive than AC or DC-powered watermakers. Engine systems are belt-driven, with an automatic clutch. An engine-based watermaker should be your first option if you want large quantities of fresh drinking water.
How Watermakers Make Drinking Water from Seawater
Even with a relatively small engine, this setup has an automatic regulator that constantly pumps the water. With that in mind, engine-powered watermakers are ideal if you want to reduce your energy consumption. To put it into perspective, an engine-driven watermaker can lower energy consumption by an enormous 80%, especially when compared with conventional AC or DC-powered watermaker systems.
If you don’t have an engine, then you will connect to the 110VAC, or you will need an inverter to step up your power from a VDC system. Inverters are not 100% efficient, but they are adequate for this.
How to Choose the Watermaker That’s Best for You
There are many factors to consider when looking for the best watermakers for your sailboat. In order to make drinking water from seawater, here are the most important things to consider.
How Much Drinking Water Do I Need?
Water is life. Everyone needs drinking water every day but sources differ on exactly what amount is required. They all said the amount varies depending on person, activity, authority, etc. The average is 3 liters/0.8 gal for men, 2 liters/0.5 gal for women) average. No mention was made of children, but we can assume about half as much as an adult.
I did a Google search and the top three authorities were Mayo Clinic (2.7l 1.7l), Web MD (3.5l, 2.5l), and BBC Good Food which didn’t give exact amounts. Some sources recommended we drink “eight glasses of water a day”. However, none of those sources defined “glass”. A glass isn’t a cup and it’s not defined as a measurement. Besides, glasses of water can be bigger or smaller, depending on who you talk to.
How Much Space Does a Watermaker need?
Do you have enough space on your boat to accommodate the type of watermaker you’re looking to buy? While most watermakers are meant to fit in the smallest of space, you should consider the actual size of the watermaker and find out whether you have enough space on your vessel to fix it.
How Much Power Does a Watermaker need?
Watermakers can run on many sources of energy such as wind and solar (if you have them on your vessel), or both. When looking for the ideal watermaker, you should consider how to power it and whether or not the watermaker has low-energy consumption, which is definitely a great feature. Again, there are also engine-driven ways for how to make drinking water from seawater. It’s important to know exactly what you’re going for.
Maintenance
Watermakers have a well-deserved reputation for being difficult to maintain. Fortunately, the equipment and their components have improved in the last few years so you should go for a model that’s easy to maintain. You should use your watermaker in water bodies that look good. Avoid using the watermaker in dirty harbors because the contaminates may clog your filters or even damage your watermaker altogether.
The Top Five Commercial Watermakers
Let’s take a look at the best watermakers available on the market right now. There are others on the market. However, these are the top five watermakers in my opinion.
Echotec Watermaker
This watermaker is one of the more durable watermakers on the market. This is essentially a series of modular watermakers ranging from 12-volt to 24-volt DC-powered models. They are efficient, have an computerized energy recovery system, and ultimate reliability to ensure that you never run out of fresh drinking water while out at sea.
This unit can produce 60 liters per hour flawlessly and with no maintenance apart from changing the filters. This model is designed for customer installation and ultra-reliable easy performance.
Spectra Katadyn PowerSurvivor
The Spectra Katadyn PowerSurvivor is arguably the most affordable watermaker currently available on the market. This model only requires 4 amps to desalinate water for your sailboat. It can produce 1.5 gallons of fresh water per hour, which is an excellent return for a watermaker of its size.
It is also one of the smallest watermakers around. You can install it either permanently or temporarily when you sell your boat or are renting. This portability is also essential if you’re looking for a space-saving model that can fit in the smallest areas.
Its simple, but rugged, design is essential in ensuring that it can perform in harsh marine conditions. This is the only model on the market that will convert to a hand-operated system or manual power if there’s a power outage.
Village Marine – Little Wonder Series
This model is one of the most efficient and economical watermakers I found. Also, this watermaker is designed with corrosion-resistant features and is one of the most serviceable units. It is quiet, reliable, and portable. These are all factors that make a watermaker great.
This model is meant for more serious sailors who are looking for various capacity options. This watermaker weighs about 68 pounds. However, it can produce up to 180 gallons of fresh drinking water each day.
The Ultra Whisper
Engineered by limited electrical options that can run on either DC or AC, The Ultra Whisper is made by Sea Recovery. This is one of the best watermakers. It’s very quiet and features an automatic operation that requires very minimal operator adjustment.
This watermaker is ideal for smaller powerboats and sailboats since it can serve as an efficient water supply. This model boasts about a 75% reduction in power consumption when compared to other models.
Ventura 150 Watermaker
This watermaker includes a controller that allows you monitor the device remotely. This is one of the most versatile models on the market. It can use both electricity and renewable energy. This model is engineered to be lightweight and energy-efficient and its compact.
The Ventura 150 watermaker is much more efficient. It can produce over 5 gallons of fresh water an hour, which makes it quite perfect for small vessels. It also has the auto store button that will automatically flush the system after every five days.
This watermaker is quiet and surprisingly compact despite its ability to produce about 150 gallons of water per day. It also gives you the option of going for the automated manual or manual model.
Conclusions
In conclusion, it’s easy to see that having a watermaker aboard your vessel is one of the first crucial steps toward being self-sufficient. With a watermaker, you’ll be able to access fresh drinking water at all times when sailing.
Modern watermaker models are well-constructed and incorporate some of the best technologies that make them efficient, reliable, and easy to install, use, and maintain.
You will be the one to decide what is ideal for you. There are many factors, such as energy consumption, efficiency, and the quantity of water produced, among many other things. You can sail for as long as you want with a watermaker. You never have to fear about running out of water. This is of great importance for enjoying your sailing adventures.
I hope some of the information in this article was useful. If you have further questions, please leave feedback and I will do more research for you!
Randy
Sources:
https://www.youtube.com/watch?v=tETjcFKccjM
https://www.youtube.com/watch?v=8k56ffiNJ8M
https://www.youtube.com/watch?v=BOdRNNPina0
https://www.cruiserowaterandpower.com/