Originally Posted by BigBeakie
Thanks Mark. Can you elaborate on that a bit? I am trying to understand the pros and cons of each of them wrt:
1. reliability/quality - most important priority for us given remote destination
2. Energy budget
impact - I think this is the point you are making re amps consumed per 100 litres product
3. TCO re consumables
4. Ease of installation & operation
As far as I can determine, there are swings and roundabouts in units using Clarke pump technology to gain efficiency. It seems that you get better power used to product produced results, but at the risk/cost of pump reliability and significantly higher initial cost, about double the cost here in Australia.
The energy savings using high pressure recovery technology looks like about 20 amps for 50 litres H2O output (Echotec 12VDC 38amps; Cape Horn 12VDC 18amps). But with a reasonable solar panel installation, that is put back in the battery bank quite quickly.
So I am not seeing what is so great about the energy recovery types of watermakers on a multihull
with decent solar input and battery storage
The Ecotech have a great reputation among cruisers in the South Pacific
re reliability, so that is what is influencing me at this point. They also seem better built, have low pressure boost pumps that can be field serviced easily, and use standard membranes that are available widely at much lower cost.
But I am at the beginning of my investigation on what unit to get so please correct me if I am missing something major to consider.
First, let me start off by saying I have no issues with Echotec - they make great products with good reputations. I talked a friend into buying
one of their AC systems just because of much of the reasons you list. I also talked him out of one of their DC systems for the reasons I list below.
For DC watermakers, amp usage is the key. You may think you have enough solar (and you might actually!), but keep in mind that these outputs are rated at 13.8V, not 12V. So to get that output from a 38A unit, you will need to be running it when your solar is pumping in >38A. Few have solar arrays that do that.
Much of this, of course, depends on your power usage and generation capabilities. You might be surprised how much power you use daily while cruising - not including your watermaker. Your solar or other sources will need to keep up with this.
To give you our example, we were running a 17A watermaker making 6gph with 480W of solar in the tropics and struggling with power management. Laundry
day had to be planned 4 days in advance and would bring us to the edge even then. We are not the most power-hungry boat we know - probably close to the middle.
If you are counting on a generator
to make up some of the charging
, then an AC watermaker makes more sense than a DC because you are running the generator
anyway (a small Honda
excepted - I mean a >3KW unit here).
Reliability of both units is very good, but like you point out, the Echotec uses bog standard parts
that are easier to source. However, if you are worried about being somewhere very remote, you won't have parts
for either anyway. Anywhere less remote, any special parts for the Spectra can be delivered easily.
And again, either of these units breaking down to the point of needing parts is very remote. If you are concerned about Spectra reliability, then do not get an automated unit. The vast majority of the problems I have seen with other people's Spectra units involve the automation. Even then, they are not dead in the water
because it is very easy to jump over those automated processes and run manually until spares can be obtained.
For the issue of consumables, as far as I know, there is no difference there. The only consumables you should ever need are common filters and preservative agent and maybe some pump oil
. All of these are found everywhere, and you can stock enough to never need to look for them again. Membranes for both are the same ones, and you will only go through those every 5-10yrs.
Ease of installation is a red herring. You are only installing it once, so "ease" is relative - who cares if it takes an extra 5hrs for one over another? Both have the ability to be modular, so you can put pieces where they fit best.
But it all comes down to power. There really is no way to describe it to someone who hasn't lived it, but power is more important than you could ever imagine. Yes, the numbers look fine on a spreadsheet, but in real-life, it doesn't look like that. Any more than 2amps/gallon just does not work unless you are sporting a solar farm with windgens in a windy area.
I repeat - it doesn't work. If you have a small unit that can run off solar, etc, it will not make enough water for your needs (if you are considering a water maker, you have needs). If you have a larger unit, it will use too much power and you will be constantly power-managing and planning.
I'm not being pedantic - just offering my experience. I won't be offended if you ignore it.
Now cost is something I can't comment on. If the Spectra is twice the cost of the Echotec, that is a budget issue and personal. In the US, I don't think the cost differential is that great.
Another thing to consider is how you will actually be cruising. The South Pacific is not entirely without its civilization, and few cruisers get lost
in the most remote places for many years at a time. Maybe your worries about parts and reliability are a bit larger than they need to be? If a new watermaker survives its first month, the vast odds are that it will be trouble-free for easily the next 5 years, when it may need a new membrane and some basic servicing.