Voile et Voilieres.
French language yachting magazine.

Cover edition September 2002.
Pages 98, 99, 100 & 101.

Published by Sernas sarl. 21, Rue du Fauberg Saint-Antoine. Paris.

Audited average sales 2001:  99,500 copies monthly.

(Translation and original images reproduced with permission of Voile et Voilieres.)

The following is a translation into English with the exception of a common French exclamation "La mer a boire" which literally means "Drink the sea" (or ocean). The expression is widespread and is unconnected with coastal or marine matters. The English language equivalent in Britain would be: "Pigs will fly". Both expressions imply something which is impossible or at least improbable. In the interests of preserving the general nuance of the text, the English equivalent is substituted where applicable. The expression is repeated a number of times through the text.

Jacques Cohen (translator)

(Banner heading over double page spread)
Click images to see larger versions


A watermaker that needs no electricity !

Pigs will fly ! 

The waterlog in action !

Shown behind our Sun Fizz, the Waterlog (a model 200), produces drinking water at the rate of 6 liters per hour at 5 knots. the higher the speed, the higher the output.

What an invention !

To produce pure water without needing any energy source aboard a sailing boat is the secret of Waterlog. We have exclusively tested this desalinator near Marseille. We got the first refreshing swallows from this equipment which will revolutionize the everyday life aboard, from small cruisers to long haul yachts.

This only happens once every ten years. Even then..... When has there last been any truly new equipment to enhance the quality of life for the cruising elite ? Comparisons may be the advent of the portable GPS, and the autopilot.....

We can think of natural systems for the production of energy, solar panels, wind generators and turbine generators. The development of smaller watermakers capable of functioning with a little less power...... Ah, but to have as much drinking water as you could wish for......  now, that is something else. Most of them require lots of energy, a complicated installation, and a price that makes many people think twice about having one on board.

This is exactly where Waterlog comes in: it can be used immediately, for there is a total absence of any installation because there are no mechanical or electrical parts involved and no energy at all is needed other than the movement of the boat. As for price, functionality, high quality of make and distribution of Waterlog is concerned, this brings the price down spectacularly, in fact, there is just nothing like it.

Reverse osmosis. When you announce what Waterlog does, a skeptical response is universal, "It just cannot possibly work !" We must wonder how many times the engineers at Waterlog have heard this rebuttal ?   To create drinking water without any control instruments, systems, electric motors, no valves of any kind......  This sounds more like magic than reality - or the work of many years !  It is a fact that it originally took five years to bring this to fruition.

Before explaining how Waterlog works, one must explain the principle of reverse osmosis, a principle which governs all desalinators. If you separate two liquids, say, sea water and pure drinking water, with a semi-permeable membrane, the least concentrated liquid (the drinking water) will pass through the membrane to dilute the contaminated liquid which is the salt water. The more salty the liquid the higher the osmotic pressure becomes. If you want to make drinking water from sea water, you must reverse the principle. Thus it is called `reverse osmosis`. When you force the saline water to break away the salt by filtering it with a membrane using a high pressure pump, then you will get drinking water which  is usually 99% pure.

The laboratory analysis: Perfectly pure !

The water analysis was done by Wolff Environmental Laboratories:- The water produced by the Waterlog was found to be of a purity and neutrality that is exemplary. In fact, due to the procedure of reverse osmosis, the majority of minerals and metals had been removed and only remained in minute quantities. For example, tap water contains about 200 mg/L, and the Waterlog product contained only 61.5 mg/L. This means that the water is four times better than tap water, in spite of the fact that it came directly from the sea.

Metals such as zinc, magnesium, copper and minerals such as potassium and calcium were shown to be virtually eliminated. This could be expected as the membrane pores used are only 0.5 nanometers in diameter. All of the bacteria in suspension, viruses, endotoxins and the majority of micropollutants and metalorganic traces were removed.

As to the taste, the water is devoid of any taste or flavour and the PH is neutral. Without these elements, the water produced by Waterlog cannot be consumed indefinitely without having another food source of vitamin supplements. As for storing the water, it can be stored for a very long time without expecting purity degradation.

(End of lab. report panel)

(Side panel under picture of man putting it in the water):-

A simple operation

How can anyone conceive of a high pressure pump working without any power ?  Clever, the principle of Waterlog exploits a propeller which rotates proportional to the speed of the boat, irrespective of whether you are navigating under sail or engine. For Waterlog to work you need a minimum speed as the quicker the rotation of the propeller, the more pressure is created. In nature, osmotic pressure is high, 29 bar. In the case of Waterlog, it makes 60 bar for the first droplets of drinking water, which requires that the speed must be 3.5 to 4.0 knots. The more the speed increases, the more pressure the pump creates and the more water is produced. It is a simple Biblical fact though that this must have an eventual limit.

Click image to see larger version

(Text contained within the dominant photograph of a man sitting holding a Waterlog)

An astonishing silhouette. In all its nudity, Waterlog shows the sum total of its components:- the towing cable, its soft drinking water exit tube, and the removable propeller and hydroplanes. 

The unique components

Waterlog is pure genius in its compactness and ingenuity. Unlike any other electrical or electromechanical desalinators which are made, Waterlog carries out the complete process within itself from A to Z. You can see from the photographs that the product resembles at the same time both a torpedo or a 

trailing sonar device. The stainless steel unit needs only two things to assemble - you attach the propeller, and plug in the towing cable with its hydroplanes into the top of the unit. The hydroplanes articulate themselves in a reverse sense. When one takes an angle to make it dive, the other moves to make it surface. They prevent the cable from twisting up onto itself. This is similar to the way a helicopter functions. In this case, the hydroplanes act as dynamic stabilizers. The hydroplanes act in opposition to the torque of the pump, dissipating the unwanted rotational drive in the body of the Waterlog. It stabilizes about 8 inches below the surface of the water. 

You must attach the tow cable to a strong fixed point on the boat so it cannot be lost. The cable is constructed of layers braided stainless steel which gives it its suppleness, and is covered with a plastic sleeve for ease of manipulation and protection. It has a small inner tube which brings the drinking water to the boat. You can send it directly to the ships tank or just into a large jerry-can with big capacity !

The deployment of the unit needs little precaution: the speed must be low as possible, preferably stopped. Remember that as the cable is 33 feet long you must have at least 33 feet depth below the boat !  All done ?  Yes, all you have to do now is navigate !

In theory, the first time you use your Waterlog, it must be immersed for some time to enable it to flood with water and displace the air which primes the pump at the heart of the system ready to work.

Click image to see larger version

(Top header box contains a reproduction of
part of a Patent Office technical drawing and
the annotations therein refer to world
patents and to the principle of operation. It
is not considered necessary to translate

Production of water

Anxious - yes we were, but after a quarter of an hour at just over 5 knots, (which is the right amount of time for the pressure to rise to 60 bar), the first droplets of appeared which were quickly followed by a steady stream of drinking water !

Pigs have flown !

In the middle of July, with water temperature at 19 degrees C., we were obtaining 6 liters of water per  hour at 5 knots. Therefore it certainly works ! To stop production, all one has to do is bring it back on board - job done.....  To have water again, just drop it back in the water. No installation is needed, very easy to handle, extremely easy and quick to stow away - It`s a dream. So, is Waterlog the ultimate weapon ?


(Center panel)
On the evidence, the Waterlog is going to play a major role in safety, as to function it only needs a minimal speed of the boat.

Some questions

What is the loss of speed incurred by trailing the unit ? On the 12 M. Sun Fizz sail boat we used for the tests, we estimated the speed loss at 0.3 knots. Is that serious ? Well, it is up to you to decide, but you are not obliged to trail the Waterlog night and day !

6 liters per hour - is that enough ? We had at our disposal  the middle size model 200 for the tests, although the 300 produces 50% more, it does have a higher drag factor. One must realize that, for example, the Sun Fizz has only 250 liters capacity in the water tank ! The simple fact of trailing the Waterlog during the passage to Corsica enabled the obtaining of 120 liters of water ! - not bad for a machine which is absolutely silent, uses no power, non polluting - that aspect is easily forgotten...  and its simple functionality.

Does it always work ?  It appears that the Waterlog may surface quite quickly after you exceed 6 knots. The output of water is not necessarily lessened, but the manufacturers indicate that when when the sea is very rough you should avoid using it.

A revolution

The waterlog is not destined for large spacious professional yachts that have boundless energy available on board, but it is destined for cruisers which have scarce energy and limited water tank capacity. Its function only depends on the minimal speed of the cruiser. The vast majority of cruisers are amateur, pleasure cruising, monohull boats which vary in length between 9 and 12 M.  Waterlog rightly say that the average passage speed of a cruiser is rarely more than 6 knots - the optimum speed of the Waterlog !  I make a toast to them, I drink to them with my drinking water !

A salt free regime !

The output of a desalinator depends on the temperature of the sea and its salt content. If cold and concentrated this will lessen the output than if the water were warm and less salty. 3% per degree between 5 and 35 degrees C. The manufacturer says that there is minimal servicing requirements. In fact the filters  can be re-used indefinitely. The membrane can last 5 to 10 years according salinity. It only takes 10 minutes to change and involves removing three screws......

If you do not use your Waterlog for a certain amount of time, you put in a biocide for quarter of an hour, and you can stow it away without bacteria developing. Our tests reveal that the cable can resist a tensile load of 4 tonnes in the event of the Waterlog becoming snagged on rocks - which is not to be recommended !

The lower the point of attachment to the boat the more the waterlog will remain submerged. So, rather than clip it to the base of a stanchion, it is better to fix a mounting as near as possible to the water on a dedicated bolt. There is a Waterlog model for catamarans, with smaller hydroplanes to cope with higher speeds and elevations but we doubt that it will stop the Waterlog from surfing. It is better to devise a way if attaching it as close as possible to the water level - but if you cruise above 10 knots, just forget it !

The propeller spins at speeds above 1,000 rpm. so any shark attacking it will have a toothache !

(Antoine Sezerat.  [Yacht equipment].  Magazine Voile et Voiliers).

(Underwater photography by Pierre Martin-Razi)

(Side bar with man pouring the Waterlog output directly into his mouth)

Pigs do fly.

From the producer to the consumer.....

Water coming out of the Waterlog beautifully direct to the consumer. It only lacks the minerals.

(End of feature article).