length of raw water inlet for watermaker?

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zefender

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I fitted a watermaker over the weekend (smiles proudly, a bit surprised at unusual DIY success). After much deliberation (though obviously not enough), I decided due to weight considerations, proximity to tank, noise etc, the best place for the watermaker would be in a void/locker under the forepeak bunk. There, I can fill the fresh water tank simply and the saline waste water can tee into the sink outlet. For the raw water inlet, I've tee'd in the raw engine cooling inlet (apparently OK, given the watermaker model I have). The problem is the (doh!) the engine is at the back of the boat, so the inlet pipe is about 15 metres long. The pump should be OK to suck this up and I've fitted a shut off valve at the beginning of the pipe. However, I'm a bit concerned about the amount of seawater that might remain in the pipe. Might it start to 'go off' a bit like a loo inlet? Will this be cleared out as the priming process runs (i.e. before useable water production). Will I poison myself and crew? Should I just cut a hole in the hole (well below the waterline, to allow for roll etc)and be done with it or is the long pipe OK?
 
Mine isnt that long, but I see no problem, even if the water does go "off" which it will, the priming before water production will clear all that water out. I used a heads inlet for mine, up forward, mine is also under a forward berth. No use of toilet when watermaking!!! Outlet is a bit too close!
 
I don't know about your watermaker but we are able to flush the seawater intake pipe on ours with freshwater using a simple three-way divert valve.

Not sure how much better it is having fresh water rather than seawater in the pipework, but it makes me feel better!
 
From the installation manual of the spectra - should read the same for yours I guess.

Installation Basics
The Spectra Watermakers are designed for energy efficiency. All aspects of the system have been optimized for this goal, therefore any changes in the basic layout or components will most likely reduce this efficiency. The overall length of the feed, discharge and high pressure hoses have little effect on performance and can even help smooth out the Clark Pump shift pulses but that every hose bend or 90° fitting absorbs power. Since a minimum amount of power is used to run the system, there is little allowance for waste. Avoid adding 90° fittings. Use gentle hose bends where possible. Careful consideration of the direction of water flow through the pre-filters and boost pump in relation to how they mount will minimize hose lengths and turns. The system diagram shows the components mounted port side on the aft face of a bulkhead. If the layout was mirrored to the starboard side, the hose runs would be much more convoluted. A good installation will be a proper compromise between minimum hose and wire runs, accessibility, environment and esthetics.
Thruhulls
It is recommended that a designated 3/4” intake thru-hull and seacock be installed for the system as far below the water line as possible . Sharing a thru-hull with another system is acceptable, but can introduce unforeseen problems such as intermittent flow restriction, air bubbles and contaminates. If the system is sharing an intake thru-hull, the intake Y valve can be used to shut off water to the system.
Do not install the intake close to or down stream of a head discharge. Install as far below the water line and as close to center line as possible to avoid contamination and air induction.

We recommend that a reputable boatyard install any underwater thru-hulls.

The discharge thru-hull should be mounted above the waterline, in or just above the boot stripe to minimize water lift. Having the discharge feed into a cockpit or sink drain will work, but can make an unpleasant gurgle sound.

Double clamp all hose connections below the water line if possible.

Fittings
Ian
 
Hi ian

Thanks for that.

We've a Katadyn 80E and yes, it says pretty much the same although it does suggest that the inlet pump can cope with a fair degree of rise. I was concerned about the sucking of air due to heeling, which is why (as well as not having to cut another through hull) I opted for the engine intake. people will just have to cross their legs while we're making water!. If we were to have fitted the inlet through a new through hull fitting in front of heads etc, it would be so far forward that, ith a bit of rock and roll, it'd probably allow some air in anyway. The inlet pipe is a decent diameter (it only neds to draw about 35 gallons/hour and there are no 90 degree turns etc - it's more the length which concerned me.

Boat still out of water for a few weeks whilst final(ish) preps are underway then we're off, and hopefully producing loads of luvverly water for Mrs Zefender's needs - oh, and enough leccie to run the thing of course!
 
After a few days of non-use the organic matter in the pipe will decompose. The most noticeable product of that is dissolved Hydrogen Sulphide. You might do well to ask the manufacturers if that will damage the membranes. Chlorine in tapwater will kill them very quickly so it wouldn't be surprising if other chemicals have the same effect.

Having said that, our intake pipe is around 7ft and it has given no trouble nor were we warned about it or told to flush the pipe. We had far more trouble with air being sucked in and the pumps losing prime.
 
Depends on what type of freshwater, if its tap water, beware of chlorine, it kills membranes, very quickly, Now ask me how much they cost!!! Doh!
 
Only have enough leccie probably (engine plus Duogen) to run it for a couple of hours daily - just 6 galls or so. I tested the shower a couple of weeks ago to see how much it uses per minute - a bit shocking! 20 second shower anyone?
 
Tee hee - how is it they can be so violent - poor old Tome still have a cauliflower ear from last weekend.

I tried to tell Mrs G about trying to use water with restraint! I jumped in the shower after her, Stone cold, hmmmm best say nought...


Ian
 
Yes, I'm planning to gently unfold these issues when we're 150 miles or so offshore so it's all a bit of 'serendipity' - though the lack of space to dodge the blows worries me a bit.
 
Not sure of the rest of your plumbing but if you have a holding tank (dunno if you do) then a T into the heads flush (if that's seawater - dunno if it is) would be better for the watermaker. Better in terms of shorter pipe, I mean. The fact it is close to the black water skin fittings doesn't matter. You only need to be sure not to dump the holding tank when making water, but as the tank dump will be every few days that's hardly an inconvenience

I worry about water makers on long transocean passages. What is your plan B if it fails? Surely you need 2 watermakers? Or do you take enough bottled water that you could survive (without washing) even if the water maker packs up?
 
Do have a holding tank but the inlet isn't high enough when heeling (which is one advantage of two heads - one for each tack).

Plan A is to keep the water tanks as full as we can (300 ltrs), using the watermaker every day - that way, we've always got a reserve should the thing break down. We'll be alternating use of the tanks so that if one bursts, we'll only lose some, rather than potentially all, of our supply. We're also taking 150litres of mineral water and another 100 litres in 20litre containers. 4 crew - about 22 day passage. Oh, and I've also got one of those Waterlog trailing thingies which may (or may not!) work. This excludes soft (and hard) drinks but since some of these are diuretics, I haven't included them. So we've got enough to survive, albeit cutting back on non-essential use as a Plan B. We'll also have a good few weeks before the transat to test how the machine works.

I was surprised to hear that some ARC folk pick up their brand new boats in Las Palmas and just head off after just a couple of trial sails.
 
I don't think your pipe is a problem.

I fired my water maker up last night, took a deep breath and flicked open the manual for a startup proceedure and he presto it only worked.
There will be no problem with the pump drawing water, and any old water drawn through will be pumped straight out of the brine discharge.
Have you plumbed in the Y bits for the freshwater flush etc.....and pickling and do you have a PPM solids meter to test the water you've made before you divert it into the tank?

Ian
 
Hey, well done!

I think we're there on the pickling set up (but need to check). Since I've a shut off valve on the inlet, I'll probably just attach a freshwater hose to that. I have a meter of some sort but haven't studied what it actually does yet!
 
Great when the "product" starts to flow, I didn't think I'd ever drink the water out of Northney Marina!

Valves you need!!

Salty side of watermaker:
Inlet through hull - standard seacock to a
Y valve on the inlet pipe - to choose to intake raw seawater or stored manufactured water for a flush/pickle from a bucket.

Brine discharge Y in pipe to flushing bucket or exit to sink fitting.

Fresh side - Y valve to allow water testing before diverting product to the tank.

Well that's what I got anyway.

Thinking about the operation of the beast and the amount of time used in anger I think it will be pickled at lot more than it will be in use, you really need the valve switching.

The golden rule apparently is not to let it get mouldy, keep using it or pickle it.

Oh, and as usual with boats - one of the pipe connections on the high pressure side leaks and it's location? Yep you've guessed it, on the back of the pump!!

Ian
 
Where can I get the Y valves? Having trouble sourcing them in Barcelona. Got the one on the inlet filter, but need one for the waste and product, different sizes. Any help would be appreciated.
 
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