Testing a watermaker in a river

[LifesBetterWhenYoureBeating]

Hi there,


I'm in the process of buying a sailboat which is in a river (Rio Dulce) and that's where the "sea" trial will take place, so I'm wondering how I could go about testing that the watermaker is actually able to desalinate water... Would it be possible to use a bucket of salty water to feed it? Any other suggestions?


Cheers

[Deep Blue Water]

The Rio Dulce in Guatemala? If that's the case the ocean doesn't seem too far away, if it was me I'd definitely test in salt water.

[LifesBetterWhenYoureBeating]

Originally Posted by Deep Blue Water

The Rio Dulce in Guatemala? If that's the case the ocean doesn't seem too far away, if it was me I'd definitely test in salt water.

Seems to be around 20nm from the marina to the sea and I'm not sure the broker will be willing to make such a long sea trial

[Deep Blue Water]

Yes, but...watermakers are expensive. One could argue that filtering river water isn't really a test of the unit, is it?

[dcarratt]

The manual for my Dessalator watermaker says "the membranes may be damaged by operation in brackish or fresh water" so maybe a long test in a river is not ideal.

You could theoretically test the unit by connecting the inlet pipe and the seawater discharge pipe to a large bucket. You will need to circulate a lot of salty water because it may take a minute to get up to pressure and then you will get maybe one eighth of the circulating water as "pure" output water.

In practice, if the unit switches on and you can see a significant pressure increase across the membranes then the unit will most likely be fine (or at least a cheap fix). You basically want to know that the membranes are intact and can be pressurised.

[waterman46]

Depends on how automated this particular unit is. Mine is all manual. I have a valves to manually switch the salt water inlet and discharge, and the fresh water product to short hoses that I place in a water bucket. Normally this configuration is used for pickling - flushing preservative or cleaning solution through the membrane and pumps. But you could just make your own clean salt water with non-chlorinated water and put that in the bucket. After about 5 minutes with all three hoses in the bucket, pull up the product hose and test it for salt. You'll need a TDS meter.

Owner may not want you to do that, so the previous post might be all you can really do. In any case, I would not put any of this product water in the tank before I could verify it's got a TDS < 250ppm.

[ozdigennaro]

Don't fool around. To test a watermaker, you must input salt water.

[Stewie12]

Make sure whatever you do that you do not use chlorinated water as it will take out the membranes and they are expensive..

[Sailshabby]

Depending on everything else, you could play hardball and subtract the cost of a new one from any offer, just in case.

[srbigham]

First question. What brand is it? Second is there a manual for it on the boat? Contact the MFG for a suggested process.

My Spectra has a process for first time commissioning following a pickling process. Good luck.

[GreenWave]

Most owners are going to likely push back on a full test of a watermaker.

Some things to consider:
Is it currently being used? When was it last used? When were the filters last changed? Is it pickled? How long has it been pickled? If it is pickled and they let you test it be sure you can re-pickle immeidately, otherwise you risk ruining the membranes.

[LifesBetterWhenYoureBeating]

It is a Spectra Catalina MPC5000. I'm pretty sure it's been pickled but hasn't been used in at least a year as the boat has been in a marina in Rio Dulce all this time. I found a manual for it online, so I'm going to see what else I can find out there



Thanks a lot for all the suggestions so far!

[Tellie]

Originally Posted by GreenWave

Most owners are going to likely push back on a full test of a watermaker.

Some things to consider:
Is it currently being used? When was it last used? When were the filters last changed? Is it pickled? How long has it been pickled? If it is pickled and they let you test it be sure you can re-pickle immeidately, otherwise you risk ruining the membranes.

Why? It would be a big red flag for me. If they are balking at that, what else would they not like a thorough test on.

[Tellie]

Originally Posted by gsalgado

It is a Spectra Catalina MPC5000. I'm pretty sure it's been pickled but hasn't been used in at least a year as the boat has been in a marina in Rio Dulce all this time. I found a manual for it online, so I'm going to see what else I can find out there



Thanks a lot for all the suggestions so far!

I've worked on a Spectra or two before. Before you buy is exactly the time to properly test this watermaker. I would suggest that you get a hold of some artificial ocean and a hydrometer if you can't get offshore. Any pet store that sells salt water fish will have this or order it on line. A Catalina300MPC5000 is a straight forward system. But these are older Spectras and you want to know far more than just the condition of the membrane. The membrane is the cheap part of this system. You can take your chances but as SailShabby said, I would hold back some money in escrow for this. That is really good and wise advice. Here's the story I hear a lot with watermakers. I bought the boat four months ago and I'm just now getting around to the watermaker. The surveyor said he applied power and it came on. I look at it for 15 minutes and say, it's going to cost around 4-5K to fix. If you need any help with this just ask.

[LifesBetterWhenYoureBeating]

Originally Posted by Tellie

I've worked on a Spectra or two before. Before you buy is exactly the time to properly test this watermaker. I would suggest that you get a hold of some artificial ocean and a hydrometer if you can't get offshore. Any pet store that sells salt water fish will have this or order it on line. A Catalina300MPC5000 is a straight forward system. But these are older Spectras and you want to know far more than just the condition of the membrane. The membrane is the cheap part of this system. You can take your chances but as SailShabby said, I would hold back some money in escrow for this. That is really good and wise advice. Here's the story I hear a lot with watermakers. I bought the boat four months ago and I'm just now getting around to the watermaker. The surveyor said he applied power and it came on. I look at it for 15 minutes and say, it's going to cost around 4-5K to fix. If you need any help with this just ask.

Thanks @Tellie, I'm definitely going to test it as best as I can before buying, but the survey/trial is in just 3 days and I don't think I'll be able to get a hydrometer (either in Rio Dulce or online) in time. However, maybe I could feed it salty mineral (to ensure it's not chlorinated) water ? If I go down that route, would it be enough to use a TDS meter (which I'm hoping someone in the area may be able to lend me) before/after adding salt to the water, to ensure it's salty enough? Also, how much water do you think I'd need for that?