How much water is needed
on a cruising yacht ?
The answer to this rather depends on whether one asks a medical practitioner or a manufacturer of watermakers. The latter would prefer us all to drink a lot of water indeed.....
The honest answer to this question depends on the standard of living expected on board. Persons aboard a "mega yacht" may want hot baths, dish washers and a laundry. Others will want long, hot showers, some are happy to swim and have a quick shower off. A cruising sailor on a critically short budget will have different expectations of a water supply.
Joshua Slocum`s
`SPRAY`
1896
His voyages were incredible feats at that time - he had no fresh water.....
You can decide the requirements for your own vessel from the basic facts which are as follows:-
Depending on circumstances, a person requires a minimum of 0.8 liters (1 pint / 2 mugs) per day to maintain body hydration. Below this figure body organs are potentially compromised. The possible consequences are obvious.
In temperate latitudes, an active person needs about 1.7 liters (3 pints / 6 mugs) of water or food beverages per day. Some of this is in the form of solid foodstuffs, all of which have a relatively high water content to one degree or another.
In the Sub Tropics, an active person usually needs about 2.3 to 3.0 liters or more (4 to 5 pints / 9 mugs) per day to maintain comfort. Although there will be great variation between individuals and their amount of physical activity, this is probably the typical cruising yacht scenario.
A heavily built person crewing on an ocean racing yacht being driven hard in hot humid tropics may require up to 9 liters (20 mugs) per day.
(We hope Capt. Slocum would have forgiven us - we have cheated a little with this photo....)
From Joshua Slocum & "SPRAY" - to portable watermakers and GPS in 100 years....
Times change.....
He had no fresh water for his circumnavigation....
There is a simple guideline to adequate body hydration. This indicates a daily water requirement equal to approximately 3% of the persons body weight. Milk, juice, or soup can not be a complete substitute for that entire water requirement due to their fat, fiber and / or solids content. Caffinated coffee, tea etc., and alcoholic beverages (due to their diuretic effect) are not appropriate substitutes.
Drinking water direct from the ocean...
The real answer?
Most cruising couples use between 4 and 6 gallons per day total water consumed from the ships tanks. Some 1 gallon is used for drinking and the balance is accounted for by showers, cooking, etc. For example, this equates to about three hours running time per day for a water powered Waterlog 200 watermaker ($2575 - £1392 no fitting costs ) or four hours for an electric Pur 40E watermaker ($2990 plus fitting costs).
If kept clean, all watermakers on the market produce good water. Reverse osmosis is a well proven and highly reliable method of desalination, in use for many years. A watermakers enemy is fine water borne material (plankton etc.) which can block filters, and internal bacteria if allowed to develop within a poorly maintained unit. All watermakers must be chemically treated from time to time to maintain optimum performance. Waterlog provides packs of tiny jars of simple, single shot treatments, the cost of which is about $30 per year for the average cruising vessel.
watermakers
watermakers
Note: When considering fitting a watermaker, we are buying water to meet the needs of the crew - NOT the amount of water produced per hour.
Does it matter what the output per hour is? - No.
What matters is that there is a simple and reliable way to safely provide water for the daily requirements of crew comfort. The vast majority of cruising vessels do not require more than about 4 to 10 gallons per day. The average cruising vessel wants 2 to 3 gallons per person per day. This is represented by a sensible but modest lifestyle where, for example, seawater is used for dishwashing and drinking water is used to rinse and also for a quick showering off after swimming.
Is it logical to spend $5,800 (£3,600) plus installation cost (plus Tax if applicable in your area), on a machine that produces 150 gallons per day when the required water can be obtained far more simply for $1392 and no installation cost? No.
If at the same time, we can dispense with maintenance, back flushing, buckets, pipes, leaks, valves, wires and flat batteries.....
Just drop a Waterlog over the stern. When you have enough, drop it in a locker....
The advantage of the bigger yacht watermakers is that the water need for the day is made more quickly, reducing the time the engine will have to be run, either to drive the watermaker pump, or to recharge the battery bank to make good the heavy current drain incurred by the watermaker.
In practice, this means that the average engine or battery driven yacht watermaker will produce about 1 mug of drinking water in about 11/2 to 4 minutes. The big engine driven sets take about 30 seconds.
The `NORTHERN LIGHT` Liverpool bound from Sydney. March 1863. She had no water.....
In the case of a Waterlog, as it is water powered and consumes no onboard energy, engine running, noise and batteries are no longer of any consideration. Being reliant on the environmental energy available from moment to moment, it will take 2 to 8 minutes upwards to produce a mug of water, depending on the speed of the vessel, sea state, sea temperature, etc. (Waterlogs do not produce water below about 4 knots, but in a liferaft they can be used by hand. In emergency, if becalmed, just clip on the optional 12 Volt motor).
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Above: Converts to manual power for liferaft use |
Above: Converts to D.C. Motor power when the vessel is at anchor |
Above: Portable Above: Water powered on passage
Water powered, or hand powered, or battery powered. The most versatile and reliable watermaker in the World. There is nothing else like it - check it out for yourself.
When you want drinking water, just tow it for a while....
You can have an endless supply for $2183 (£1180) (Model 100)
and you can try it for 7 days.... You can get one here now on-line
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Note: Prices can vary in different markets due to fluctuations in the rates of currency exchange. Plus Postage / freight. Figures and specifications are intended as a guideline. E&OE
