During our voyage around the world we consumed about 4,000 liters of drinking water and other beverages, plus about 18,000 liters of tank water (mostly used for washing): now try to figure the hard work of replenishing our tanks, considering that very seldom shops and water taps are in the immediate vicinity of the yacht at anchor.
Even in the rare cases when we were moored to a pontoon provided with water taps, the concern remained about the potability of this water of unknown provenance!
Since some years, the solution has become available also for small craft after having become ubiquitous aboard ships, i.e. produce your own water with a DISSALATOR: basically these devices pump a large amount of sea water (which must be reasonably free from chemical and biological pollution) passing it at high pressure through a membrane that lets through only the fresh water, leaving salts and other impurities in the discharge water.
Typically a watermaker needs to process about 10 liters of sea water to produce 1 liter of fresh water, and the product quality is very good, in fact even too good because it’s short of salts and some people advise to improve its salt content with additives. We never bothered because we did not use this water for drinking.
Due to the fact that the water circulating through the device is mostly sea water, with its content of micro-organisms and algae, it is not advisable to leave the system unused for more than about one week, otherwise it’s recommended to run through the system about 10 liters of fresh water just before stopping the watermaker; if it will be left unused for an even longer period, a disinfectant should also be added to this fresh water.
We had a 30 liter/hour LIVOL watermaker, therefore during passages we usually ran it for one or two hours every one or two days, typically while the engine was running to recharge the batteries; erring on the safe side, we always performed the fresh-water rinsing before stopping the device, so our procedure was as follows:
1) start the dissalator with the fresh-water outlet diverted towards a 15-liter jerrycan where we collected the first fresh water output.
2) after about 20-30 minutes, when the tank was full, we turned the fresh water output towards the boat’s main tank
3) when we had produced the desired quantity of water (we were trying to keep the tanks full) we turned the water inlet pipe to suck the fresh water from the previously-filled jerrycan: this takes a little more than one minute, so we had to be ready to switch off the watermaker before air could enter the pipes, risking damage to the high-pressure pump.
Every 6 months we replaced the filters on the sea-water inlet pipe and rinsed the whole system running a biocide through it for a complete disinfection (after which the first water produced by the system must be discarded).
A bit tricky, maybe, but try and compare it with lugging nearly 1,000 jerrycans back and forwards from the boat to the nearest tap!
A great freedom then, but where is the downside? As a matter of fact, there are a few:
– COST: a watermaker suitable for a small yacht costs upwards of 6-10,000 Euros
– Electrical consumption: our needed about 7 Amps, not trivial in the daily power balance.
– The MAINTENANCE, not difficult but critical: if the membrane is damaged the repair is going to cost dearly (and the membrane needs to be replaced every few years anyway)
– BULK: the device is bulky and it may be not easy to find a place for it on a small-medium sized yacht (our LIVOL had separate filters and high-pressure pump, which allowed for some flexibility in the installation, but the main unit is bulky anyway)
– If the boat is left unattended in COLD CLIMATES, the dissalator must be dismantled, to prevent freezing of the liquid which must be left inside it
Conversely, RELIABILITY has greatly improved in the last years: in the past, a lot of horror stories were reported, many of them apparently due to INSTALLATION problems: for example, a common issue was with the sea-water intake position, which allowed air bubbles to get in the pipes when the boat was running at speed, reducing the watermaker’s output and risking to damage the high-pressure pump.
Nearly all boats in the Blue Water Rally were equipped with a watermaker, and problems were extremely few: only one boat had a mayor issue, caused by the pump running dry and overheating.
IS IT WORTH THE HASSLE? Maybe not on a yacht sailing only in Europe or the Mediterranean (although also in this case the freedom of not having to get to a port every few days just for water is attractive), but I WOULD NOT MAKE WITHOUT IT for a cruise anywhere else (okay, I’m not thinking of North America or Australia).
Note for our faithful readers: from now on, we will try to put these notes simultaneously (well, almost!) also on our web-site: http://www.shaula3.ws – Please note that the web version may be richer, complete with photos and drawings, where applicable.