By 'eck there's some rubbish posted here by those who haven't 'done it' yet. Marina water heavy? They don't add iron filings to it , you know. I also don't advise drinking
salt water. Collecting rain water is not a dependable method and of course depends on where you are in the first place as to whether you actually get any.
90 litres per hour is perhaps a bit excessive. Most people settle for between 40 and sixty, depending on
budget. A couple of questions you need to answer: Do you want a 12 volt
watermaker, one that takes its drive off the
engine or an ac system (need a generator). Do you want a fully automatic model (self-testing) or are you happy to taste the water yourself before routing it into the tank?
I was quoted aropund about £5K for a fully automatic, 50 litre per hour unit, but settled for the Echotec model for £2880 (depends on exchange rate, it's priced in US dollars). It's 12 volt manual test. Fitting took about a day (again, depends on where you fit it of course). I do agree they're a bit heavy on power, but then again you'll only run it for an hour a day. My combination of wind/solar generation copes OK. Opinions vary a little as to how long you can leave it between operating the watermaker before you have to re-biocide. Echotec reckon up to a week, others say a couple of days. One thing is for sure, the human tongue is a good tester ~ if it tastes 'funny' then it isn't right.
A watermaker makes life much easy when cruising. If you go from marina to marina it probably isn't worth the expense. Traditionally, cruisers would always take a couple of cans ashore with them and top up with potable water, but this isn't always available (it is common in
Europe, though). In dry areas the locals might not take too kindly to you helping yourself to 'their' water and in places you have to pay for it anyway.
For longer legs (say around the 3 week + mark) the trick is to make sure you always have enough water onboard to safely finish the trip if the watermaker goes tits up, so for example you wouldn't have showers every day for a week then try the watermaker. It depends on the
boat, but my plan (the same as the last Atlantic crossing) is to use the watermaker to top off
solar showers first and use the internal
tanks for drinking/cooking. Keep a 25 litre can of dedicated 'just in case'
drinking water and top up the tanks every couple of days.
Watermakers are also good in 'out of the way'
anchorages, allowing you a prolonged stay.
Do you NEED one for
blue water cruising, no. Is it nice to have one, YES! There are
trade offs, price/power
consumption and the trick is to never get yourself into a situation where you NEED the output from the watermaker. If you're going to have one, get it fitted before you leave (true for most bits of kit). Once you've left you'll be on a
budget and virtually all engineers want the
boat in a marina before working on it (yet more expense).